--- linux-2.6.19/block/Kconfig +++ linux-2.6.19/block/Kconfig @@ -54,3 +54,14 @@ endif source block/Kconfig.iosched + + +config XVMALLOC + tristate "XVMalloc" + default m + +config RAMZSWAP + tristate "Compressed Swap Device" + depends on XVMALLOC && LZO_COMPRESS && LZO_DECOMPRESS + default m + --- linux-2.6.19/block/Makefile +++ linux-2.6.19/block/Makefile @@ -10,3 +10,7 @@ obj-$(CONFIG_IOSCHED_CFQ) += cfq-iosched.o obj-$(CONFIG_BLK_DEV_IO_TRACE) += blktrace.o + +obj-$(CONFIG_XVMALLOC) += ramzswap/ +obj-$(CONFIG_RAMZSWAP) += ramzswap/ + --- linux-2.6.19/block/ramzswap/compat.h +++ linux-2.6.19/block/ramzswap/compat.h @@ -0,0 +1,36 @@ +#ifndef _RAMZSWAP_COMPAT_H_ +#define _RAMZSWAP_COMPAT_H_ + +#include +#include + +/* Uncomment this if you are using swap free notify patch */ +#define CONFIG_SWAP_NOTIFIERS + +#if LINUX_VERSION_CODE <= KERNEL_VERSION(2,6,23) +#define BIO_IO_ERROR(bio) bio_io_error(bio, PAGE_SIZE) +#define BIO_ENDIO(bio, error) bio_endio(bio, PAGE_SIZE, error) +#else +#define BIO_IO_ERROR(bio) bio_io_error(bio) +#define BIO_ENDIO(bio, error) bio_endio(bio, error) +#endif + +#ifndef pr_err +#define pr_err(fmt, arg...) \ + printk(KERN_ERR fmt, ##arg) +#endif + +#ifndef pr_warning +#define pr_warning(fmt, arg...) \ + printk(KERN_WARNING fmt, ##arg) +#endif + +#ifndef pr_info +#define pr_info(fmt, arg...) \ + printk(KERN_ERR fmt, ##arg) +#endif + +#undef BIT +#define BIT(x) (1UL << (x)) + +#endif --- linux-2.6.19/block/ramzswap/Makefile +++ linux-2.6.19/block/ramzswap/Makefile @@ -0,0 +1,8 @@ + +EXTRA_CFLAGS := -DCONFIG_BLK_DEV_RAMZSWAP_STATS \ + -I../xvmalloc \ + -g -Wall + +obj-m += xvmalloc.o +obj-m += ramzswap.o + --- linux-2.6.19/block/ramzswap/ramzswap.c +++ linux-2.6.19/block/ramzswap/ramzswap.c @@ -0,0 +1,1135 @@ +/* + * Compressed RAM based swap device + * + * Copyright (C) 2008, 2009 Nitin Gupta + * + * This RAM based block device acts as swap disk. + * Pages swapped to this device are compressed and + * stored in memory. + * + * Released under the terms of GNU General Public License Version 2.0 + * + * Project home: http://compcache.googlecode.com + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include "compat.h" +#include "ramzswap.h" + +/* Globals */ +static struct ramzswap rzs; +static struct ramzswap_stats stats; +/* + * Pages that compress to larger than this size are + * forwarded to backing swap, if present or stored + * uncompressed in memory otherwise. + */ +static unsigned int MAX_CPAGE_SIZE; + +/* Module params (documentation at end) */ +static unsigned long disksize_kb; +static unsigned long memlimit_kb; +static char *backing_swap; + +static int __init ramzswap_init(void); +static struct block_device_operations ramzswap_devops = { + .owner = THIS_MODULE, +}; + +static int test_flag(u32 index, enum rzs_pageflags flag) +{ + return rzs.table[index].flags & BIT(flag); +} + +static void set_flag(u32 index, enum rzs_pageflags flag) +{ + rzs.table[index].flags |= BIT(flag); +} + +static void clear_flag(u32 index, enum rzs_pageflags flag) +{ + rzs.table[index].flags &= ~BIT(flag); +} + +static int page_zero_filled(void *ptr) +{ + u32 pos; + u64 *page; + + page = (u64 *)ptr; + + for (pos = 0; pos != PAGE_SIZE / sizeof(*page); pos++) { + if (page[pos]) + return 0; + } + + return 1; +} + +/* + * Given pair, provide a dereferencable pointer. + */ +static void *get_ptr_atomic(u32 pagenum, u16 offset, enum km_type type) +{ + unsigned char *page; + + page = kmap_atomic(pfn_to_page(pagenum), type); + return page + offset; +} + +static void put_ptr_atomic(void *ptr, enum km_type type) +{ + kunmap_atomic(ptr, type); +} + +static void ramzswap_flush_dcache_page(struct page *page) +{ +#ifdef CONFIG_ARM + int flag = 0; + /* + * Ugly hack to get flush_dcache_page() work on ARM. + * page_mapping(page) == NULL after clearing this swap cache flag. + * Without clearing this flag, flush_dcache_page() will simply set + * "PG_dcache_dirty" bit and return. + */ + if (PageSwapCache(page)) { + flag = 1; + ClearPageSwapCache(page); + } +#endif + flush_dcache_page(page); +#ifdef CONFIG_ARM + if (flag) + SetPageSwapCache(page); +#endif +} + +#if defined(STATS) +static struct proc_dir_entry *proc; + +static int proc_ramzswap_read(char *page, char **start, off_t off, + int count, int *eof, void *data) +{ + int len; + size_t succ_writes, mem_used; + unsigned int good_compress_perc = 0, no_compress_perc = 0; + + mem_used = xv_get_total_size_bytes(rzs.mem_pool) + + (stats.pages_expand << PAGE_SHIFT); + + if (off > 0) { + *eof = 1; + return 0; + } + +#define K(x) ((x) >> 10) + /* Basic stats */ + len = sprintf(page, + "DiskSize: %8zu kB\n", + (size_t)(K(rzs.disksize))); + + if (rzs.backing_swap) { + /* This must always be less than ComprDataSize */ + len += sprintf(page + len, + "MemLimit: %8zu kB\n", + K(rzs.memlimit)); + } + + succ_writes = stats.num_writes - stats.failed_writes; + + if (succ_writes && stats.pages_stored) { + good_compress_perc = stats.good_compress * 100 + / stats.pages_stored; + no_compress_perc = stats.pages_expand * 100 + / stats.pages_stored; + } + + /* Extended stats */ + len += sprintf(page + len, + "NumReads: %8llu\n" + "NumWrites: %8llu\n" + "FailedReads: %8llu\n" + "FailedWrites: %8llu\n" + "InvalidIO: %8llu\n" + "NotifyFree: %8llu\n" + "ZeroPages: %8u\n" + "GoodCompress: %8u %%\n" + "NoCompress: %8u %%\n" + "PagesStored: %8u\n" + "PagesUsed: %8zu\n" + "OrigDataSize: %8zu kB\n" + "ComprDataSize: %8zu kB\n" + "MemUsedTotal: %8zu kB\n", + stats.num_reads, + stats.num_writes, + stats.failed_reads, + stats.failed_writes, + stats.invalid_io, + stats.notify_free, + stats.pages_zero, + good_compress_perc, + no_compress_perc, + stats.pages_stored, + mem_used >> PAGE_SHIFT, + (size_t)(K(stats.pages_stored << PAGE_SHIFT)), + (size_t)(K(stats.compr_size)), + (size_t)(K(mem_used))); + + if (rzs.backing_swap) { + /* This must always be less than ComprDataSize */ + len += sprintf(page + len, + "BDevNumReads: %8llu\n" + "BDevNumWrites: %8llu\n", + stats.bdev_num_reads, + stats.bdev_num_writes); + } + + return len; +} +#endif /* STATS */ + +/* + * Check if value of backing_swap module param is sane. + * Claim this device and set ramzswap size equal to + * size of this block device. + */ +static int setup_backing_swap(void) +{ + int error = 0; + struct inode *inode; + struct file *swap_file; + struct address_space *mapping; + struct block_device *bdev = NULL; + + if (backing_swap == NULL) { + pr_debug(C "backing_swap param not given\n"); + goto out; + } + + pr_info(C "Using backing swap device: %s\n", backing_swap); + + swap_file = filp_open(backing_swap, O_RDWR | O_LARGEFILE, 0); + if (IS_ERR(swap_file)) { + pr_err(C "Error opening backing device: %s\n", backing_swap); + error = -EINVAL; + goto out; + } + + mapping = swap_file->f_mapping; + inode = mapping->host; + + if (S_ISBLK(inode->i_mode)) { + bdev = I_BDEV(inode); + error = bd_claim(bdev, ramzswap_init); + if (error < 0) { + bdev = NULL; + goto bad_param; + } + rzs.old_block_size = block_size(bdev); + error = set_blocksize(bdev, PAGE_SIZE); + if (error < 0) + goto bad_param; + } else { + /* TODO: support for regular file as backing swap */ + pr_info(C "%s is not a block device.\n", backing_swap); + error = -EINVAL; + goto out; + } + + rzs.swap_file = swap_file; + rzs.backing_swap = bdev; + rzs.disksize = i_size_read(inode); + BUG_ON(!rzs.disksize); + + return 0; + +bad_param: + if (bdev) { + set_blocksize(bdev, rzs.old_block_size); + bd_release(bdev); + } + filp_close(swap_file, NULL); + +out: + rzs.backing_swap = NULL; + return error; +} + +/* + * Check if request is within bounds and page aligned. + */ +static inline int valid_swap_request(struct bio *bio) +{ + if (unlikely( + (bio->bi_sector >= (rzs.disksize >> SECTOR_SHIFT)) || + (bio->bi_sector & (SECTORS_PER_PAGE - 1)) || + (bio->bi_vcnt != 1) || + (bio->bi_size != PAGE_SIZE) || + (bio->bi_io_vec[0].bv_offset != 0))) { + + return 0; + } + + /* swap request is valid */ + return 1; +} + +static void ramzswap_free_page(size_t index) +{ + u32 clen; + void *obj; + + u32 pagenum = rzs.table[index].pagenum; + u32 offset = rzs.table[index].offset; + + if (unlikely(!pagenum)) { + if (test_flag(index, RZS_ZERO)) { + clear_flag(index, RZS_ZERO); + stat_dec(stats.pages_zero); + } + return; + } + + if (unlikely(test_flag(index, RZS_UNCOMPRESSED))) { + clen = PAGE_SIZE; + __free_page(pfn_to_page(pagenum)); + clear_flag(index, RZS_UNCOMPRESSED); + stat_dec(stats.pages_expand); + goto out; + } + + obj = get_ptr_atomic(pagenum, offset, KM_USER0); + clen = xv_get_object_size(obj) - sizeof(struct zobj_header); + put_ptr_atomic(obj, KM_USER0); + + xv_free(rzs.mem_pool, pagenum, offset); + stat_dec_if_less(stats.good_compress, clen, PAGE_SIZE / 2 + 1); + +out: + stats.compr_size -= clen; + stat_dec(stats.pages_stored); + + rzs.table[index].pagenum = 0; + rzs.table[index].offset = 0; +} + +#ifdef CONFIG_SWAP_FREE_NOTIFY +/* + * callback function called when swap_map[offset] == 0 + * i.e page at this swap offset is no longer used + */ +static void ramzswap_free_notify(unsigned long index) +{ + if (rzs.table[index].pagenum) { + ramzswap_free_page(index); + stat_inc(rzs.stats.notify_free); + } +} +#endif + +int handle_zero_page(struct bio *bio) +{ + void *user_mem; + struct page *page = bio->bi_io_vec[0].bv_page; + + user_mem = get_ptr_atomic(page_to_pfn(page), 0, KM_USER0); + memset(user_mem, 0, PAGE_SIZE); + put_ptr_atomic(user_mem, KM_USER0); + + ramzswap_flush_dcache_page(page); + + set_bit(BIO_UPTODATE, &bio->bi_flags); + BIO_ENDIO(bio, 0); + return 0; +} + +int handle_uncompressed_page(struct bio *bio) +{ + u32 index; + struct page *page; + unsigned char *user_mem, *cmem; + + page = bio->bi_io_vec[0].bv_page; + index = bio->bi_sector >>SECTORS_PER_PAGE_SHIFT; + + user_mem = get_ptr_atomic(page_to_pfn(page), 0, KM_USER0); + cmem = get_ptr_atomic(rzs.table[index].pagenum, + rzs.table[index].offset, KM_USER1); + + memcpy(user_mem, cmem, PAGE_SIZE); + put_ptr_atomic(user_mem, KM_USER0); + put_ptr_atomic(cmem, KM_USER1); + + ramzswap_flush_dcache_page(page); + + set_bit(BIO_UPTODATE, &bio->bi_flags); + BIO_ENDIO(bio, 0); + return 0; +} + + +/* + * Called when request page is not present in ramzswap. + * Its either in backing swap device (if present) or + * this is an attempt to read before any previous write + * to this location - this happens due to readahead when + * swap device is read from user-space (e.g. during swapon) + */ +int handle_ramzswap_fault(struct bio *bio) +{ + void *user_mem; + struct page *page = bio->bi_io_vec[0].bv_page; + + /* + * Always forward such requests to backing swap + * device (if present) + */ + if (rzs.backing_swap) { + stat_dec(stats.num_reads); + stat_inc(stats.bdev_num_reads); + bio->bi_bdev = rzs.backing_swap; + return 1; + } + + /* + * Its unlikely event in case backing dev is + * not present + */ + pr_debug(C "Read before write on swap device: " + "sector=%lu, size=%u, offset=%u\n", + (ulong)(bio->bi_sector), bio->bi_size, + bio->bi_io_vec[0].bv_offset); + user_mem = kmap(page); + memset(user_mem, 0, PAGE_SIZE); + kunmap(page); + + set_bit(BIO_UPTODATE, &bio->bi_flags); + BIO_ENDIO(bio, 0); + return 0; +} + +#ifdef CONFIG_SWAP_NOTIFIERS +static int ramzswap_slot_free_notify(struct notifier_block *self, + unsigned long index, void *swap_file) +{ + ramzswap_free_page(index); + stat_inc(stats.notify_free); + return 0; +} + +static struct notifier_block ramzswap_slot_free_nb = { + .notifier_call = ramzswap_slot_free_notify +}; + +static int ramzswap_swapon_notify(struct notifier_block *self, + unsigned long swap_id, void *swap_file) +{ + int ret; + struct block_device *bdev; + struct inode *inode; + + inode = ((struct file *)swap_file)->f_mapping->host; + bdev = I_BDEV(inode); + if ((struct ramzswap *)(bdev->bd_disk->private_data) != &rzs) + return 0; + + ret = register_swap_event_notifier(&ramzswap_slot_free_nb, + SWAP_EVENT_SLOT_FREE, swap_id); + if (ret) + pr_err("Error registering swap free notifier\n"); + return ret; +} + +static int ramzswap_swapoff_notify(struct notifier_block *self, + unsigned long swap_id, void *swap_file) +{ + struct block_device *bdev; + struct inode *inode; + + inode = ((struct file *)swap_file)->f_mapping->host; + bdev = I_BDEV(inode); + if ((struct ramzswap *)(bdev->bd_disk->private_data) != &rzs) + return 0; + + unregister_swap_event_notifier(&ramzswap_slot_free_nb, + SWAP_EVENT_SLOT_FREE, swap_id); + return 0; +} + +static struct notifier_block ramzswap_swapon_nb = { + .notifier_call = ramzswap_swapon_notify +}; + +static struct notifier_block ramzswap_swapoff_nb = { + .notifier_call = ramzswap_swapoff_notify +}; +#endif + +int ramzswap_read(struct bio *bio) +{ + int ret; + u32 index; + size_t clen; + struct page *page; + struct zobj_header *zheader; + unsigned char *user_mem, *cmem; + + stat_inc(stats.num_reads); + + page = bio->bi_io_vec[0].bv_page; + index = bio->bi_sector >> SECTORS_PER_PAGE_SHIFT; + + if (test_flag(index, RZS_ZERO)) + return handle_zero_page(bio); + + /* Requested page is not present in compressed area */ + if (!rzs.table[index].pagenum) + return handle_ramzswap_fault(bio); + + /* Page is stored uncompressed since its incompressible */ + if (unlikely(test_flag(index, RZS_UNCOMPRESSED))) + return handle_uncompressed_page(bio); + + user_mem = get_ptr_atomic(page_to_pfn(page), 0, KM_USER0); + clen = PAGE_SIZE; + + cmem = get_ptr_atomic(rzs.table[index].pagenum, + rzs.table[index].offset, KM_USER1); + + ret = lzo1x_decompress_safe( + cmem + sizeof(*zheader), + xv_get_object_size(cmem) - sizeof(*zheader), + user_mem, &clen); + + put_ptr_atomic(user_mem, KM_USER0); + put_ptr_atomic(cmem, KM_USER1); + + /* should NEVER happen */ + if (unlikely(ret != LZO_E_OK)) { + pr_err(C "Decompression failed! err=%d, page=%u\n", + ret, index); + stat_inc(stats.failed_reads); + goto out; + } + + ramzswap_flush_dcache_page(page); + + set_bit(BIO_UPTODATE, &bio->bi_flags); + BIO_ENDIO(bio, 0); + return 0; + +out: + BIO_IO_ERROR(bio); + return 0; +} + +int ramzswap_write(struct bio *bio) +{ + int ret, fwd_write_request = 0; + u32 offset; + size_t clen, index; + struct zobj_header *zheader; + struct page *page, *page_store; + unsigned char *user_mem, *cmem, *src; + + stat_inc(stats.num_writes); + + page = bio->bi_io_vec[0].bv_page; + index = bio->bi_sector >> SECTORS_PER_PAGE_SHIFT; + + src = rzs.compress_buffer; + + /* + * System swaps to same sector again when the stored page + * is no longer referenced by any process. So, its now safe + * to free the memory that was allocated for this page. + */ + if (rzs.table[index].pagenum) + ramzswap_free_page(index); + + /* + * No memory ia allocated for zero filled pages. + * Simply clear zero page flag. + */ + if (test_flag(index, RZS_ZERO)) { + stat_dec(stats.pages_zero); + clear_flag(index, RZS_ZERO); + } + + mutex_lock(&rzs.lock); + + user_mem = get_ptr_atomic(page_to_pfn(page), 0, KM_USER0); + if (page_zero_filled(user_mem)) { + put_ptr_atomic(user_mem, KM_USER0); + mutex_unlock(&rzs.lock); + stat_inc(stats.pages_zero); + set_flag(index, RZS_ZERO); + + set_bit(BIO_UPTODATE, &bio->bi_flags); + BIO_ENDIO(bio, 0); + return 0; + } + + if (rzs.backing_swap && + (stats.compr_size > rzs.memlimit - PAGE_SIZE)) { + put_ptr_atomic(user_mem, KM_USER0); + mutex_unlock(&rzs.lock); + fwd_write_request = 1; + goto out; + } + + ret = lzo1x_1_compress(user_mem, PAGE_SIZE, src, &clen, + rzs.compress_workmem); + + put_ptr_atomic(user_mem, KM_USER0); + + if (unlikely(ret != LZO_E_OK)) { + mutex_unlock(&rzs.lock); + pr_err(C "Compression failed! err=%d\n", ret); + stat_inc(stats.failed_writes); + goto out; + } + + /* + * Page is incompressible. Forward it to backing swap + * if present. Otherwise, store it as-is (uncompressed) + * since we do not want to return too many swap write + * errors which has side effect of hanging the system. + */ + if (unlikely(clen > MAX_CPAGE_SIZE)) { + if (rzs.backing_swap) { + mutex_unlock(&rzs.lock); + fwd_write_request = 1; + goto out; + } + + clen = PAGE_SIZE; + page_store = alloc_page(GFP_NOIO | __GFP_HIGHMEM); + if (unlikely(!page_store)) { + mutex_unlock(&rzs.lock); + stat_inc(stats.failed_writes); + goto out; + } + + offset = 0; + set_flag(index, RZS_UNCOMPRESSED); + stat_inc(stats.pages_expand); + rzs.table[index].pagenum = page_to_pfn(page_store); + src = get_ptr_atomic(page_to_pfn(page), 0, KM_USER0); + goto memstore; + } + + if (xv_malloc(rzs.mem_pool, clen + sizeof(*zheader), + &rzs.table[index].pagenum, &offset, + GFP_NOIO | __GFP_HIGHMEM)) { + mutex_unlock(&rzs.lock); + pr_info(C "Error allocating memory for compressed " + "page: %zu, size=%zu\n", index, clen); + stat_inc(stats.failed_writes); + if (rzs.backing_swap) + fwd_write_request = 1; + goto out; + } + +memstore: + rzs.table[index].offset = offset; + + cmem = get_ptr_atomic(rzs.table[index].pagenum, + rzs.table[index].offset, KM_USER1); + +#if 0 + /* Back-reference needed for memory defragmentation */ + if (!test_flag(index, RZS_UNCOMPRESSED)) { + zheader = (struct zobj_header *)cmem; + zheader->table_idx = index; + cmem += sizeof(*zheader); + } +#endif + + memcpy(cmem, src, clen); + + put_ptr_atomic(cmem, KM_USER1); + if (unlikely(test_flag(index, RZS_UNCOMPRESSED))) + put_ptr_atomic(src, KM_USER0); + + /* Update stats */ + stats.compr_size += clen; + stat_inc(stats.pages_stored); + stat_inc_if_less(stats.good_compress, clen, PAGE_SIZE / 2 + 1); + + mutex_unlock(&rzs.lock); + + set_bit(BIO_UPTODATE, &bio->bi_flags); + BIO_ENDIO(bio, 0); + return 0; + +out: + if (fwd_write_request) { + stat_inc(stats.bdev_num_writes); + bio->bi_bdev = rzs.backing_swap; + return 1; + } + + BIO_IO_ERROR(bio); + return 0; +} + +/* + * Handler function for all ramzswap I/O requests. + */ +static int ramzswap_make_request(struct request_queue *queue, struct bio *bio) +{ + int ret = 0; + + if (!valid_swap_request(bio)) { + stat_inc(stats.invalid_io); + BIO_IO_ERROR(bio); + return 0; + } + + switch (bio_data_dir(bio)) { + case READ: + ret = ramzswap_read(bio); + break; + + case WRITE: + ret = ramzswap_write(bio); + break; + } + + return ret; +} + +/* + * Swap header (1st page of swap device) contains information + * to indentify it as a swap partition. Prepare such a header + * for ramzswap device (ramzswap0) so that swapon can identify + * it as swap partition. In case backing swap device is provided, + * copy its swap header. + */ +static int setup_swap_header(union swap_header *s) +{ + int ret = 0; + struct page *page; + struct address_space *mapping; + union swap_header *backing_swap_header; + + /* + * There is no backing swap device. Create a swap header + * that is acceptable by swapon. + */ + if (rzs.backing_swap == NULL) { + s->info.version = 1; + s->info.last_page = (rzs.disksize >> PAGE_SHIFT) - 1; + s->info.nr_badpages = 0; + memcpy(s->magic.magic, "SWAPSPACE2", 10); + return 0; + } + + /* + * We have a backing swap device. Copy its swap header + * to ramzswap device header. If this header contains + * invalid information (backing device not a swap + * partition, etc.), swapon will fail for ramzswap + * which is correct behavior - we don't want to swap + * over filesystem partition! + */ + + /* Read the backing swap header (code from sys_swapon) */ + mapping = rzs.swap_file->f_mapping; + if (!mapping->a_ops->readpage) { + ret = -EINVAL; + goto out; + } + + page = read_mapping_page(mapping, 0, rzs.swap_file); + if (IS_ERR(page)) { + ret = PTR_ERR(page); + goto out; + } + + backing_swap_header = kmap(page); + memcpy(s, backing_swap_header, sizeof(*s)); + if (s->info.nr_badpages) { + pr_info("Cannot use backing swap with bad pages (%u)\n", + s->info.nr_badpages); + ret = -EINVAL; + } + /* + * ramzswap disksize equals number of usable pages in backing + * swap. Set last_page in swap header to match this disksize + * ('last_page' means 0-based index of last usable swap page). + */ + s->info.last_page = (rzs.disksize >> PAGE_SHIFT) - 1; + kunmap(page); + +out: + return ret; +} + +static void ramzswap_set_disksize(size_t totalram_bytes) +{ + rzs.disksize = disksize_kb << 10; + + if (!disksize_kb) { + pr_info(C + "disk size not provided. You can use disksize_kb module " + "param to specify size.\nUsing default: (%u%% of RAM).\n", + DEFAULT_DISKSIZE_PERC_RAM + ); + rzs.disksize = DEFAULT_DISKSIZE_PERC_RAM * + (totalram_bytes / 100); + } + + if (disksize_kb > 2 * (totalram_bytes >> 10)) { + pr_info(C + "There is little point creating a ramzswap of greater than " + "twice the size of memory since we expect a 2:1 compression " + "ratio. Note that ramzswap uses about 0.1%% of the size of " + "the swap device when not in use so a huge ramzswap is " + "wasteful.\n" + "\tMemory Size: %zu kB\n" + "\tSize you selected: %lu kB\n" + "Continuing anyway ...\n", + totalram_bytes >> 10, disksize_kb + ); + } + + rzs.disksize &= PAGE_MASK; + pr_info(C "disk size set to %zu kB\n", rzs.disksize >> 10); +} + +/* + * memlimit cannot be greater than backing disk size. + */ +static void ramzswap_set_memlimit(size_t totalram_bytes) +{ + int memlimit_valid = 1; + rzs.memlimit = memlimit_kb << 10; + + if (!rzs.memlimit) { + pr_info(C "memory limit not set. You can use " + "memlimit_kb module param to specify limit."); + memlimit_valid = 0; + } + + if (rzs.memlimit > rzs.disksize) { + pr_info(C "memory limit cannot be greater than " + "disksize: limit=%zu, disksize=%zu", + rzs.memlimit, rzs.disksize); + memlimit_valid = 0; + } + + if (!memlimit_valid) { + size_t mempart, disksize; + pr_info(C "\nUsing default: MIN[(%u%% of RAM), " + "(backing disk size)].\n", + DEFAULT_MEMLIMIT_PERC_RAM); + mempart = DEFAULT_MEMLIMIT_PERC_RAM * (totalram_bytes / 100); + disksize = rzs.disksize; + rzs.memlimit = mempart > disksize ? disksize : mempart; + } + + if (rzs.memlimit > totalram_bytes / 2) { + pr_info(C + "Its not advisable setting limit more than half of " + "size of memory since we expect a 2:1 compression ratio. " + "Limit represents amount of *compressed* data we can keep " + "in memory!\n" + "\tMemory Size: %zu kB\n" + "\tLimit you selected: %lu kB\n" + "Continuing anyway ...\n", + totalram_bytes >> 10, memlimit_kb + ); + } + + rzs.memlimit &= PAGE_MASK; + BUG_ON(!rzs.memlimit); + + pr_info(C "memory limit set to %zu kB\n", rzs.memlimit >> 10); +} + +static int __init ramzswap_init(void) +{ + int ret; + size_t num_pages, totalram_bytes; + struct page *page; + void *swap_header; + + mutex_init(&rzs.lock); + + ret = setup_backing_swap(); + if (ret) + goto fail; + + totalram_bytes = totalram_pages << PAGE_SHIFT; + + if (rzs.backing_swap) + ramzswap_set_memlimit(totalram_bytes); + else + ramzswap_set_disksize(totalram_bytes); + + rzs.compress_workmem = kmalloc(LZO1X_MEM_COMPRESS, GFP_KERNEL); + if (rzs.compress_workmem == NULL) { + pr_err(C "Error allocating compressor working memory\n"); + ret = -ENOMEM; + goto fail; + } + + rzs.compress_buffer = kmalloc(2 * PAGE_SIZE, GFP_KERNEL); + if (rzs.compress_buffer == NULL) { + pr_err(C "Error allocating compressor buffer space\n"); + ret = -ENOMEM; + goto fail; + } + + num_pages = rzs.disksize >> PAGE_SHIFT; + rzs.table = vmalloc(num_pages * sizeof(*rzs.table)); + if (rzs.table == NULL) { + pr_err(C "Error allocating ramzswap address table\n"); + ret = -ENOMEM; + goto fail; + } + memset(rzs.table, 0, num_pages * sizeof(*rzs.table)); + + page = alloc_page(__GFP_ZERO); + if (page == NULL) { + pr_err(C "Error allocating swap header page\n"); + ret = -ENOMEM; + goto fail; + } + rzs.table[0].pagenum = page_to_pfn(page); + set_flag(0, RZS_UNCOMPRESSED); + + swap_header = kmap(page); + ret = setup_swap_header((union swap_header *)(swap_header)); + kunmap(page); + if (ret) { + pr_err(C "Error setting swap header\n"); + goto fail; + } + + rzs.disk = alloc_disk(1); + if (rzs.disk == NULL) { + pr_err(C "Error allocating disk structure\n"); + ret = -ENOMEM; + goto fail; + } + + rzs.disk->first_minor = 0; + rzs.disk->fops = &ramzswap_devops; + /* + * It is named like this to prevent distro installers + * from offering ramzswap as installation target. They + * seem to ignore all devices beginning with 'ram' + */ + strcpy(rzs.disk->disk_name, "ramzswap0"); + + rzs.disk->major = register_blkdev(0, rzs.disk->disk_name); + if (rzs.disk->major < 0) { + pr_err(C "Cannot register block device\n"); + ret = -EFAULT; + goto fail; + } + + rzs.disk->queue = blk_alloc_queue(GFP_KERNEL); + if (rzs.disk->queue == NULL) { + pr_err(C "Cannot register disk queue\n"); + ret = -EFAULT; + goto fail; + } + + rzs.disk->private_data = &rzs; + set_capacity(rzs.disk, rzs.disksize >> SECTOR_SHIFT); + blk_queue_make_request(rzs.disk->queue, ramzswap_make_request); + + add_disk(rzs.disk); + + rzs.mem_pool = xv_create_pool(); + if (!rzs.mem_pool) { + pr_err(C "Error creating memory pool\n"); + ret = -ENOMEM; + goto fail; + } + +#if defined(STATS) + proc = create_proc_entry("ramzswap", S_IRUGO, NULL); + if (proc) + proc->read_proc = &proc_ramzswap_read; + else { + ret = -ENOMEM; + pr_warning(C "Error creating proc entry\n"); + goto fail; + } +#endif + + /* + * Pages that compress to size greater than this are forwarded + * to physical swap disk (if backing dev is provided) + */ + if (rzs.backing_swap) + MAX_CPAGE_SIZE = MAX_CPAGE_SIZE_BDEV; + else + MAX_CPAGE_SIZE = MAX_CPAGE_SIZE_NOBDEV; + + pr_debug(C "Max compressed page size: %u bytes\n", MAX_CPAGE_SIZE); + +#ifdef CONFIG_SWAP_NOTIFIERS + ret = register_swap_event_notifier(&ramzswap_swapon_nb, + SWAP_EVENT_SWAPON, 0); + if (ret) { + pr_err("Error registering swapon notifier\n"); + goto fail; + } + + ret = register_swap_event_notifier(&ramzswap_swapoff_nb, + SWAP_EVENT_SWAPOFF, 0); + if (ret) { + unregister_swap_event_notifier(&ramzswap_swapoff_nb, + SWAP_EVENT_SWAPON, 0); + pr_err("Error registering swapoff notifier\n"); + goto fail; + } +#endif + + pr_debug(C "Initialization done!\n"); + return 0; + +fail: + if (rzs.disk != NULL) { + if (rzs.disk->major > 0) + unregister_blkdev(rzs.disk->major, rzs.disk->disk_name); + del_gendisk(rzs.disk); + } + + if (rzs.table && rzs.table[0].pagenum) + __free_page(pfn_to_page(rzs.table[0].pagenum)); + kfree(rzs.compress_workmem); + kfree(rzs.compress_buffer); + vfree(rzs.table); + xv_destroy_pool(rzs.mem_pool); +#if defined(STATS) + if (proc) + remove_proc_entry("ramzswap", proc->parent); +#endif + pr_err(C "Initialization failed: err=%d\n", ret); + return ret; +} + +static void __exit ramzswap_exit(void) +{ + size_t index, num_pages; + num_pages = rzs.disksize >> PAGE_SHIFT; + +#ifdef CONFIG_SWAP_NOTIFIERS + unregister_swap_event_notifier(&ramzswap_swapon_nb, + SWAP_EVENT_SWAPON, 0); + unregister_swap_event_notifier(&ramzswap_swapoff_nb, + SWAP_EVENT_SWAPOFF, 0); +#endif + + unregister_blkdev(rzs.disk->major, rzs.disk->disk_name); + del_gendisk(rzs.disk); + + /* Close backing swap device (if present) */ + if (rzs.backing_swap) { + set_blocksize(rzs.backing_swap, rzs.old_block_size); + bd_release(rzs.backing_swap); + filp_close(rzs.swap_file, NULL); + } + + __free_page(pfn_to_page(rzs.table[0].pagenum)); + kfree(rzs.compress_workmem); + kfree(rzs.compress_buffer); + + /* Free all pages that are still in ramzswap */ + for (index = 1; index < num_pages; index++) { + u32 pagenum, offset; + + pagenum = rzs.table[index].pagenum; + offset = rzs.table[index].offset; + + if (!pagenum) + continue; + + if (unlikely(test_flag(index, RZS_UNCOMPRESSED))) + __free_page(pfn_to_page(pagenum)); + else + xv_free(rzs.mem_pool, pagenum, offset); + } + + vfree(rzs.table); + xv_destroy_pool(rzs.mem_pool); + +#if defined(STATS) + remove_proc_entry("ramzswap", proc->parent); +#endif + pr_debug(C "cleanup done!\n"); +} + +/* + * This param is applicable only when there is no backing swap device. + * We ignore this param in case backing dev is provided since then its + * always equal to size of the backing swap device. + * + * This size refers to amount of (uncompressed) data it can hold. + * For e.g. disksize_kb=1024 means it can hold 1024kb worth of + * uncompressed data even if this data compresses to just, say, 100kb. + * + * Default value is used if this param is missing or 0 (if its applicable). + * Default: [DEFAULT_DISKSIZE_PERC_RAM]% of RAM + */ +module_param(disksize_kb, ulong, 0); +MODULE_PARM_DESC(disksize_kb, "ramzswap device size (kB)"); + +/* + * This param is applicable only when backing swap device is provided. + * This refers to limit on amount of (compressed) data it can hold in + * memory. Note that total amount of memory used (MemUsedTotal) can + * exceed this memlimit since that includes memory wastage due to + * fragmentation and metadata overhead. + * + * Any additional data beyond this limit is forwarded to backing + * swap device. TODO: allow changing memlimit at runtime. + * + * Default value is used if this param is missing or 0 (if its applicable). + * Default: MIN([DEFAULT_MEMLIMIT_PERC_RAM]% of RAM, Backing Device Size) + */ +module_param(memlimit_kb, ulong, 0); +MODULE_PARM_DESC(memlimit_kb, "ramzswap memory limit (kB)"); + +/* + * This is block device to be used as backing store for ramzswap. + * When pages more than memlimit_kb as swapped to ramzswap, we store + * any additional pages in this device. We may also move some pages + * from ramzswap to this device in case system is really low on + * memory (TODO). + * + * This device is not directly visible to kernel as a swap device + * (/proc/swaps will only show /dev/ramzswap0 and not this device). + * Managing this backing device is the job of ramzswap module. + */ +module_param(backing_swap, charp, 0); +MODULE_PARM_DESC(backing_swap, "Backing swap partition"); + +module_init(ramzswap_init); +module_exit(ramzswap_exit); + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Nitin Gupta "); +MODULE_DESCRIPTION("Compressed RAM Based Swap Device"); --- linux-2.6.19/block/ramzswap/ramzswap.h +++ linux-2.6.19/block/ramzswap/ramzswap.h @@ -0,0 +1,160 @@ +/* + * Compressed RAM based swap device + * + * Copyright (C) 2008, 2009 Nitin Gupta + * + * This RAM based block device acts as swap disk. + * Pages swapped to this device are compressed and + * stored in memory. + * + * Released under the terms of GNU General Public License Version 2.0 + * + * Project home: http://compcache.googlecode.com + */ + +#ifndef _RAMZSWAP_H_ +#define _RAMZSWAP_H_ + +#include "xvmalloc.h" + +/* + * Stored at beginning of each compressed object. + * + * It stores back-reference to table entry which points to this + * object. This is required to support memory defragmentation or + * migrating compressed pages to backing swap disk. + */ +struct zobj_header { +#if 0 + u32 table_idx; +#endif +}; + +/*-- Configurable parameters */ + +/* Default ramzswap disk size: 25% of total RAM */ +#define DEFAULT_DISKSIZE_PERC_RAM 25 +#define DEFAULT_MEMLIMIT_PERC_RAM 15 + +/* + * Max compressed page size when backing device is provided. + * Pages that compress to size greater than this are sent to + * physical swap disk. + */ +#define MAX_CPAGE_SIZE_BDEV (PAGE_SIZE / 2) + +/* + * Max compressed page size when there is no backing dev. + * Pages that compress to size greater than this are stored + * uncompressed in memory. + */ +#define MAX_CPAGE_SIZE_NOBDEV (PAGE_SIZE / 4 * 3) + +/* + * NOTE: MAX_CPAGE_SIZE_{BDEV,NOBDEV} sizes must be + * less than or equal to: + * XV_MAX_ALLOC_SIZE - sizeof(struct zobj_header) + * since otherwise xvMalloc would always return failure. + */ + +/*-- End of configurable params */ + +#define SECTOR_SHIFT 9 +#define SECTOR_SIZE (1 << SECTOR_SHIFT) +#define SECTORS_PER_PAGE_SHIFT (PAGE_SHIFT - SECTOR_SHIFT) +#define SECTORS_PER_PAGE (1 << SECTORS_PER_PAGE_SHIFT) + +/* Message prefix */ +#define C "ramzswap: " + +/* Debugging and Stats */ +#define NOP do { } while (0) + +#if defined(CONFIG_BLK_DEV_RAMZSWAP_STATS) +#define STATS +#endif + +#if defined(STATS) +#define stat_inc(stat) ((stat)++) +#define stat_dec(stat) ((stat)--) +#define stat_inc_if_less(stat, val1, val2) \ + ((stat) += ((val1) < (val2) ? 1 : 0)) +#define stat_dec_if_less(stat, val1, val2) \ + ((stat) -= ((val1) < (val2) ? 1 : 0)) +#else /* STATS */ +#define stat_inc(x) NOP +#define stat_dec(x) NOP +#define stat_inc_if_less(x, v1, v2) NOP +#define stat_dec_if_less(x, v1, v2) NOP +#endif /* STATS */ + +/* Flags for ramzswap pages (table[page_no].flags) */ +enum rzs_pageflags { + /* Page is stored uncompressed */ + RZS_UNCOMPRESSED, + + /* Page consists entirely of zeros */ + RZS_ZERO, + + __NR_RZS_PAGEFLAGS, +}; + +/*-- Data structures */ + +/* Indexed by page no. */ +struct table { + u32 pagenum; + u16 offset; + u8 count; /* object ref count (not yet used) */ + u8 flags; +}; + +struct ramzswap { + struct xv_pool *mem_pool; + void *compress_workmem; + void *compress_buffer; + struct table *table; + struct mutex lock; + struct gendisk *disk; + /* + * This is limit on compressed data size (stats.compr_size) + * Its applicable only when backing swap device is present. + */ + size_t memlimit; /* bytes */ + /* + * This is limit on amount of *uncompressed* worth of data + * we can hold. When backing swap device is provided, it is + * set equal to device size. + */ + size_t disksize; /* bytes */ + + /* backing swap device info */ + struct block_device *backing_swap; + struct file *swap_file; + int old_block_size; + int init_notify_callback; +}; + +struct ramzswap_stats { + /* basic stats */ + size_t compr_size; /* compressed size of pages stored - + * needed to enforce memlimit */ + /* more stats */ +#if defined(STATS) + u64 num_reads; /* failed + successful */ + u64 num_writes; /* --do-- */ + u64 failed_reads; /* can happen when memory is too low */ + u64 failed_writes; /* should NEVER! happen */ + u64 invalid_io; /* non-swap I/O requests */ + u64 notify_free; /* no. of pages freed by swap free notifier */ + u32 pages_zero; /* no. of zero filled pages */ + u32 pages_stored; /* no. of pages currently stored */ + u32 good_compress; /* no. of pages with compression ratio<=50% */ + u32 pages_expand; /* no. of incompressible pages */ + u64 bdev_num_reads; /* no. of reads on backing dev */ + u64 bdev_num_writes; /* no. of writes on backing dev */ +#endif +}; +/*-- */ + +#endif --- linux-2.6.19/block/ramzswap/xvmalloc.c +++ linux-2.6.19/block/ramzswap/xvmalloc.c @@ -0,0 +1,557 @@ +/* + * xvmalloc memory allocator + * + * Copyright (C) 2008, 2009 Nitin Gupta + * + * This code is released using a dual license strategy: BSD/GPL + * You can choose the licence that better fits your requirements. + * + * Released under the terms of 3-clause BSD License + * Released under the terms of GNU General Public License Version 2.0 + */ + +#include +#include +#include +#include +#include +#include +#include +#include + +#include "compat.h" +#include "xvmalloc.h" +#include "xvmalloc_int.h" + +static void stat_inc(u64 *value) +{ + *value = *value + 1; +} + +static void stat_dec(u64 *value) +{ + *value = *value - 1; +} + +static int test_flag(struct block_header *block, enum blockflags flag) +{ + return block->prev & BIT(flag); +} + +static void set_flag(struct block_header *block, enum blockflags flag) +{ + block->prev |= BIT(flag); +} + +static void clear_flag(struct block_header *block, enum blockflags flag) +{ + block->prev &= ~BIT(flag); +} + +/* + * Given pair, provide a derefrencable pointer. + * This is called from xv_malloc/xv_free path, so it needs to be fast. + */ +static void *get_ptr_atomic(u32 pagenum, u16 offset, enum km_type type) +{ + unsigned char *base; + + base = kmap_atomic(pfn_to_page(pagenum), type); + return base + offset; +} + +static void put_ptr_atomic(void *ptr, enum km_type type) +{ + kunmap_atomic(ptr, type); +} + +static u32 get_blockprev(struct block_header *block) +{ + return block->prev & PREV_MASK; +} + +static void set_blockprev(struct block_header *block, u16 new_offset) +{ + block->prev = new_offset | (block->prev & FLAGS_MASK); +} + +static struct block_header *BLOCK_NEXT(struct block_header *block) +{ + return (struct block_header *)((char *)block + block->size + XV_ALIGN); +} + +/* + * Get index of free list containing blocks of maximum size + * which is less than or equal to given size. + */ +static u32 get_index_for_insert(u32 size) +{ + if (unlikely(size > XV_MAX_ALLOC_SIZE)) + size = XV_MAX_ALLOC_SIZE; + size &= ~FL_DELTA_MASK; + return (size - XV_MIN_ALLOC_SIZE) >> FL_DELTA_SHIFT; +} + +/* + * Get index of free list having blocks of size greater than + * or equal to requested size. + */ +static u32 get_index(u32 size) +{ + if (unlikely(size < XV_MIN_ALLOC_SIZE)) + size = XV_MIN_ALLOC_SIZE; + size = ALIGN(size, FL_DELTA); + return (size - XV_MIN_ALLOC_SIZE) >> FL_DELTA_SHIFT; +} + +/* + * Allocate a memory page. Called when a pool needs to grow. + */ +static u32 xv_alloc_page(gfp_t flags) +{ + struct page *page; + + page = alloc_page(flags); + if (unlikely(!page)) + return 0; + + return page_to_pfn(page); +} + +/* + * Called when all objects in a page are freed. + */ +static void xv_free_page(u32 pagenum) +{ + __free_page(pfn_to_page(pagenum)); +} + +/** + * find_block - find block of at least given size + * @pool: memory pool to search from + * @size: size of block required + * @pagenum: page no. containing required block + * @offset: offset within the page where block is located. + * + * Searches two level bitmap to locate block of at least + * the given size. If such a block is found, it provides + * to identify this block and returns index + * in freelist where we found this block. + * Otherwise, returns 0 and params are not touched. + */ +static u32 find_block(struct xv_pool *pool, u32 size, + u32 *pagenum, u32 *offset) +{ + ulong flbitmap, slbitmap; + u32 flindex, slindex, slbitstart; + + /* There are no free blocks in this pool */ + if (!pool->flbitmap) + return 0; + + /* Get freelist index correspoding to this size */ + slindex = get_index(size); + slbitmap = pool->slbitmap[slindex / BITS_PER_LONG]; + slbitstart = slindex % BITS_PER_LONG; + + /* + * If freelist is not empty at this index, we found the + * block - head of this list. This is approximate best-fit match. + */ + if (test_bit(slbitstart, &slbitmap)) { + *pagenum = pool->freelist[slindex].pagenum; + *offset = pool->freelist[slindex].offset; + return slindex; + } + + /* + * No best-fit found. Search a bit further in bitmap for a free block. + * Second level bitmap consists of series of 32-bit chunks. Search + * further in the chunk where we expected a best-fit, starting from + * index location found above. + */ + slbitstart++; + slbitmap >>= slbitstart; + + /* Skip this search if we were already at end of this bitmap chunk */ + if ((slbitstart != BITS_PER_LONG) && slbitmap) { + slindex += __ffs(slbitmap) + 1; + *pagenum = pool->freelist[slindex].pagenum; + *offset = pool->freelist[slindex].offset; + return slindex; + } + + /* Now do a full two-level bitmap search to find next nearest fit */ + flindex = slindex / BITS_PER_LONG; + + flbitmap = (pool->flbitmap) >> (flindex + 1); + if (!flbitmap) + return 0; + + flindex += __ffs(flbitmap) + 1; + slbitmap = pool->slbitmap[flindex]; + slindex = (flindex * BITS_PER_LONG) + __ffs(slbitmap); + *pagenum = pool->freelist[slindex].pagenum; + *offset = pool->freelist[slindex].offset; + + return slindex; +} + +/* + * Insert block at in freelist of given pool. + * freelist used depends on block size. + */ +static void insert_block(struct xv_pool *pool, u32 pagenum, u32 offset, + struct block_header *block) +{ + u32 flindex, slindex; + struct block_header *nextblock; + + slindex = get_index_for_insert(block->size); + flindex = slindex / BITS_PER_LONG; + + block->link.prev_pagenum = 0; + block->link.prev_offset = 0; + block->link.next_pagenum = pool->freelist[slindex].pagenum; + block->link.next_offset = pool->freelist[slindex].offset; + pool->freelist[slindex].pagenum = pagenum; + pool->freelist[slindex].offset = offset; + + if (block->link.next_pagenum) { + nextblock = get_ptr_atomic(block->link.next_pagenum, + block->link.next_offset, KM_USER1); + nextblock->link.prev_pagenum = pagenum; + nextblock->link.prev_offset = offset; + put_ptr_atomic(nextblock, KM_USER1); + } + + __set_bit(slindex % BITS_PER_LONG, &pool->slbitmap[flindex]); + __set_bit(flindex, &pool->flbitmap); +} + +/* + * Remove block from head of freelist. Index 'slindex' identifies the freelist. + */ +static void remove_block_head(struct xv_pool *pool, + struct block_header *block, u32 slindex) +{ + struct block_header *tmpblock; + u32 flindex = slindex / BITS_PER_LONG; + + pool->freelist[slindex].pagenum = block->link.next_pagenum; + pool->freelist[slindex].offset = block->link.next_offset; + block->link.prev_pagenum = 0; + block->link.prev_offset = 0; + + if (!pool->freelist[slindex].pagenum) { + __clear_bit(slindex % BITS_PER_LONG, &pool->slbitmap[flindex]); + if (!pool->slbitmap[flindex]) + __clear_bit(flindex, &pool->flbitmap); + } else { + /* + * DEBUG ONLY: We need not reinitialize freelist head previous + * pointer to 0 - we never depend on its value. But just for + * sanity, lets do it. + */ + tmpblock = get_ptr_atomic(pool->freelist[slindex].pagenum, + pool->freelist[slindex].offset, KM_USER1); + tmpblock->link.prev_pagenum = 0; + tmpblock->link.prev_offset = 0; + put_ptr_atomic(tmpblock, KM_USER1); + } +} + +/* + * Remove block from freelist. Index 'slindex' identifies the freelist. + */ +static void remove_block(struct xv_pool *pool, u32 pagenum, u32 offset, + struct block_header *block, u32 slindex) +{ + u32 flindex; + struct block_header *tmpblock; + + if (pool->freelist[slindex].pagenum == pagenum + && pool->freelist[slindex].offset == offset) { + remove_block_head(pool, block, slindex); + return; + } + + flindex = slindex / BITS_PER_LONG; + + if (block->link.prev_pagenum) { + tmpblock = get_ptr_atomic(block->link.prev_pagenum, + block->link.prev_offset, KM_USER1); + tmpblock->link.next_pagenum = block->link.next_pagenum; + tmpblock->link.next_offset = block->link.next_offset; + put_ptr_atomic(tmpblock, KM_USER1); + } + + if (block->link.next_pagenum) { + tmpblock = get_ptr_atomic(block->link.next_pagenum, + block->link.next_offset, KM_USER1); + tmpblock->link.prev_pagenum = block->link.prev_pagenum; + tmpblock->link.prev_offset = block->link.prev_offset; + put_ptr_atomic(tmpblock, KM_USER1); + } + + return; +} + +/* + * Allocate a page and add it freelist of given pool. + */ +static int grow_pool(struct xv_pool *pool, gfp_t flags) +{ + u32 pagenum; + struct block_header *block; + + pagenum = xv_alloc_page(flags); + if (unlikely(!pagenum)) + return -ENOMEM; + + stat_inc(&pool->total_pages); + + spin_lock(&pool->lock); + block = get_ptr_atomic(pagenum, 0, KM_USER0); + + block->size = PAGE_SIZE - XV_ALIGN; + set_flag(block, BLOCK_FREE); + clear_flag(block, PREV_FREE); + set_blockprev(block, 0); + + insert_block(pool, pagenum, 0, block); + + put_ptr_atomic(block, KM_USER0); + spin_unlock(&pool->lock); + + return 0; +} + +/* + * Create a memory pool. Allocates freelist, bitmaps and other + * per-pool metadata. + */ +struct xv_pool *xv_create_pool(void) +{ + u32 ovhd_size; + struct xv_pool *pool; + + ovhd_size = roundup(sizeof(*pool), PAGE_SIZE); + pool = kzalloc(ovhd_size, GFP_KERNEL); + if (!pool) + return NULL; + + spin_lock_init(&pool->lock); + + return pool; +} +EXPORT_SYMBOL_GPL(xv_create_pool); + +void xv_destroy_pool(struct xv_pool *pool) +{ + kfree(pool); +} +EXPORT_SYMBOL_GPL(xv_destroy_pool); + +/** + * xv_malloc - Allocate block of given size from pool. + * @pool: pool to allocate from + * @size: size of block to allocate + * @pagenum: page no. that holds the object + * @offset: location of object within pagenum + * + * On success, identifies block allocated + * and 0 is returned. On failure, is set to + * 0 and -ENOMEM is returned. + * + * Allocation requests with size > XV_MAX_ALLOC_SIZE will fail. + */ +int xv_malloc(struct xv_pool *pool, u32 size, u32 *pagenum, u32 *offset, + gfp_t flags) +{ + int error; + u32 index, tmpsize, origsize, tmpoffset; + struct block_header *block, *tmpblock; + + *pagenum = 0; + *offset = 0; + origsize = size; + + if (unlikely(!size || size > XV_MAX_ALLOC_SIZE)) + return -ENOMEM; + + size = ALIGN(size, XV_ALIGN); + + spin_lock(&pool->lock); + + index = find_block(pool, size, pagenum, offset); + + if (!*pagenum) { + spin_unlock(&pool->lock); + if (flags & GFP_NOWAIT) + return -ENOMEM; + error = grow_pool(pool, flags); + if (unlikely(error)) + return -ENOMEM; + + spin_lock(&pool->lock); + index = find_block(pool, size, pagenum, offset); + } + + if (!*pagenum) { + spin_unlock(&pool->lock); + return -ENOMEM; + } + + block = get_ptr_atomic(*pagenum, *offset, KM_USER0); + + remove_block_head(pool, block, index); + + /* Split the block if required */ + tmpoffset = *offset + size + XV_ALIGN; + tmpsize = block->size - size; + tmpblock = (struct block_header *)((char *)block + size + XV_ALIGN); + if (tmpsize) { + tmpblock->size = tmpsize - XV_ALIGN; + set_flag(tmpblock, BLOCK_FREE); + clear_flag(tmpblock, PREV_FREE); + + set_blockprev(tmpblock, *offset); + if (tmpblock->size >= XV_MIN_ALLOC_SIZE) + insert_block(pool, *pagenum, tmpoffset, tmpblock); + + if (tmpoffset + XV_ALIGN + tmpblock->size != PAGE_SIZE) { + tmpblock = BLOCK_NEXT(tmpblock); + set_blockprev(tmpblock, tmpoffset); + } + } else { + /* This block is exact fit */ + if (tmpoffset != PAGE_SIZE) + clear_flag(tmpblock, PREV_FREE); + } + + block->size = origsize; + clear_flag(block, BLOCK_FREE); + + put_ptr_atomic(block, KM_USER0); + spin_unlock(&pool->lock); + + *offset += XV_ALIGN; + + return 0; +} +EXPORT_SYMBOL_GPL(xv_malloc); + +/* + * Free block identified with + */ +void xv_free(struct xv_pool *pool, u32 pagenum, u32 offset) +{ + void *page; + struct block_header *block, *tmpblock; + + offset -= XV_ALIGN; + + spin_lock(&pool->lock); + + page = get_ptr_atomic(pagenum, 0, KM_USER0); + block = (struct block_header *)((char *)page + offset); + + /* Catch double free bugs */ + BUG_ON(test_flag(block, BLOCK_FREE)); + + block->size = ALIGN(block->size, XV_ALIGN); + + tmpblock = BLOCK_NEXT(block); + if (offset + block->size + XV_ALIGN == PAGE_SIZE) + tmpblock = NULL; + + /* Merge next block if its free */ + if (tmpblock && test_flag(tmpblock, BLOCK_FREE)) { + /* + * Blocks smaller than XV_MIN_ALLOC_SIZE + * are not inserted in any free list. + */ + if (tmpblock->size >= XV_MIN_ALLOC_SIZE) { + remove_block(pool, pagenum, + offset + block->size + XV_ALIGN, tmpblock, + get_index_for_insert(tmpblock->size)); + } + block->size += tmpblock->size + XV_ALIGN; + } + + /* Merge previous block if its free */ + if (test_flag(block, PREV_FREE)) { + tmpblock = (struct block_header *)((char *)(page) + + get_blockprev(block)); + offset = offset - tmpblock->size - XV_ALIGN; + + if (tmpblock->size >= XV_MIN_ALLOC_SIZE) + remove_block(pool, pagenum, offset, tmpblock, + get_index_for_insert(tmpblock->size)); + + tmpblock->size += block->size + XV_ALIGN; + block = tmpblock; + } + + /* No used objects in this page. Free it. */ + if (block->size == PAGE_SIZE - XV_ALIGN) { + put_ptr_atomic(page, KM_USER0); + spin_unlock(&pool->lock); + + xv_free_page(pagenum); + stat_dec(&pool->total_pages); + return; + } + + set_flag(block, BLOCK_FREE); + if (block->size >= XV_MIN_ALLOC_SIZE) + insert_block(pool, pagenum, offset, block); + + if (offset + block->size + XV_ALIGN != PAGE_SIZE) { + tmpblock = BLOCK_NEXT(block); + set_flag(tmpblock, PREV_FREE); + set_blockprev(tmpblock, offset); + } + + put_ptr_atomic(page, KM_USER0); + spin_unlock(&pool->lock); + + return; +} +EXPORT_SYMBOL_GPL(xv_free); + +u32 xv_get_object_size(void *obj) +{ + struct block_header *blk; + + blk = (struct block_header *)((char *)(obj) - XV_ALIGN); + return blk->size; +} +EXPORT_SYMBOL_GPL(xv_get_object_size); + +/* + * Returns total memory used by allocator (userdata + metadata) + */ +u64 xv_get_total_size_bytes(struct xv_pool *pool) +{ + return pool->total_pages << PAGE_SHIFT; +} +EXPORT_SYMBOL_GPL(xv_get_total_size_bytes); + +static int __init xv_malloc_init(void) +{ + return 0; +} + +static void __exit xv_malloc_exit(void) +{ + return; +} + +module_init(xv_malloc_init); +module_exit(xv_malloc_exit); + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Nitin Gupta "); +MODULE_DESCRIPTION("xvmalloc memory allocator"); --- linux-2.6.19/block/ramzswap/xvmalloc.h +++ linux-2.6.19/block/ramzswap/xvmalloc.h @@ -0,0 +1,30 @@ +/* + * xvmalloc memory allocator + * + * Copyright (C) 2008, 2009 Nitin Gupta + * + * This code is released using a dual license strategy: BSD/GPL + * You can choose the licence that better fits your requirements. + * + * Released under the terms of 3-clause BSD License + * Released under the terms of GNU General Public License Version 2.0 + */ + +#ifndef _XVMALLOC_H_ +#define _XVMALLOC_H_ + +#include + +struct xv_pool; + +struct xv_pool *xv_create_pool(void); +void xv_destroy_pool(struct xv_pool *pool); + +int xv_malloc(struct xv_pool *pool, u32 size, u32 *pagenum, u32 *offset, + gfp_t flags); +void xv_free(struct xv_pool *pool, u32 pagenum, u32 offset); + +u32 xv_get_object_size(void *obj); +u64 xv_get_total_size_bytes(struct xv_pool *pool); + +#endif --- linux-2.6.19/block/ramzswap/xvmalloc_int.h +++ linux-2.6.19/block/ramzswap/xvmalloc_int.h @@ -0,0 +1,86 @@ +/* + * xvmalloc memory allocator + * + * Copyright (C) 2008, 2009 Nitin Gupta + * + * This code is released using a dual license strategy: BSD/GPL + * You can choose the licence that better fits your requirements. + * + * Released under the terms of 3-clause BSD License + * Released under the terms of GNU General Public License Version 2.0 + */ + +#ifndef _XVMALLOC_INT_H_ +#define _XVMALLOC_INT_H_ + +#include +#include + +/* User configurable params */ + +/* This must be greater than sizeof(LinkFree) */ +#define XV_MIN_ALLOC_SIZE 32 +#define XV_MAX_ALLOC_SIZE (PAGE_SIZE - XV_ALIGN) + +/* Must be power of two */ +#define XV_ALIGN_SHIFT 2 +#define XV_ALIGN (1 << XV_ALIGN_SHIFT) +#define XV_ALIGN_MASK (XV_ALIGN - 1) + +/* Free lists are separated by FL_DELTA bytes */ +#define FL_DELTA_SHIFT 3 +#define FL_DELTA (1 << FL_DELTA_SHIFT) +#define FL_DELTA_MASK (FL_DELTA - 1) +#define NUM_FREE_LISTS ((XV_MAX_ALLOC_SIZE - XV_MIN_ALLOC_SIZE) \ + / FL_DELTA + 1) + +#define MAX_FLI DIV_ROUND_UP(NUM_FREE_LISTS, BITS_PER_LONG) + +/* End of user params */ + +enum blockflags { + BLOCK_FREE, + PREV_FREE, + __NR_BLOCKFLAGS, +}; + +#define FLAGS_MASK XV_ALIGN_MASK +#define PREV_MASK (~FLAGS_MASK) + +struct freelist_entry { + u32 pagenum; + u16 offset; + u16 pad; +}; + +struct link_free { + u32 prev_pagenum; + u32 next_pagenum; + u16 prev_offset; + u16 next_offset; +}; + +struct block_header { + union { + /* This common header must be ALIGN bytes */ + u8 common[XV_ALIGN]; + struct { + u16 size; + u16 prev; + }; + }; + struct link_free link; +}; + +struct xv_pool { + ulong flbitmap; + ulong slbitmap[MAX_FLI]; + spinlock_t lock; + + struct freelist_entry freelist[NUM_FREE_LISTS]; + + /* stats */ + u64 total_pages; +}; + +#endif