http://lkml.org/lkml/2008/3/24/88This creates RAM based block device (called ramzswap0) which is used as swap disk. On write (swap-out): - compress page (using LZO) - Allocate required amount of memory (using TLSF) - Store reference to its location in simple array. On read (swap-in): - Get compressed page location from array - Decompress this page. It also makes required Makefile changes. Signed-off-by: Nitin Gupta <nitingupta910 at gmail dot com> --- drivers/block/Kconfig | 10 + drivers/block/Makefile | 1 + drivers/block/compcache.c | 440 +++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 451 insertions(+), 0 deletions(-) diff --git a/drivers/block/Kconfig b/drivers/block/Kconfig index 0d1d213..0cba42f 100644 --- a/drivers/block/Kconfig +++ b/drivers/block/Kconfig @@ -347,6 +347,16 @@ config BLK_DEV_RAM_SIZE The default value is 4096 kilobytes. Only change this if you know what you are doing. +config BLK_DEV_COMPCACHE + tristate "Compressed RAM based swap device" + select TLSF + select LZO_COMPRESS + select LZO_DECOMPRESS + help + This creates RAM based block device which acts as swap disk. Pages + swapped to this disk are compressed and stored in memory itself. + Project Home: http://code.google.com/p/compcache/ + config BLK_DEV_XIP bool "Support XIP filesystems on RAM block device" depends on BLK_DEV_RAM diff --git a/drivers/block/Makefile b/drivers/block/Makefile index 5e58430..b6d3dd2 100644 --- a/drivers/block/Makefile +++ b/drivers/block/Makefile @@ -12,6 +12,7 @@ obj-$(CONFIG_PS3_DISK) += ps3disk.o obj-$(CONFIG_ATARI_FLOPPY) += ataflop.o obj-$(CONFIG_AMIGA_Z2RAM) += z2ram.o obj-$(CONFIG_BLK_DEV_RAM) += brd.o +obj-$(CONFIG_BLK_DEV_COMPCACHE) += compcache.o obj-$(CONFIG_BLK_DEV_LOOP) += loop.o obj-$(CONFIG_BLK_DEV_XD) += xd.o obj-$(CONFIG_BLK_CPQ_DA) += cpqarray.o diff --git a/drivers/block/compcache.c b/drivers/block/compcache.c new file mode 100644 index 0000000..4ffcd63 --- /dev/null +++ b/drivers/block/compcache.c @@ -0,0 +1,440 @@ +/* + * Compressed RAM based swap device + * + * (C) Nitin Gupta + * + * This RAM based block device acts as swap disk. + * Pages swapped to this device are compressed and + * stored in memory. + * + * Project home: http://code.google.com/p/compcache + */ + +#include <linux/module.h> +#include <linux/kernel.h> +#include <linux/blkdev.h> +#include <linux/buffer_head.h> +#include <linux/device.h> +#include <linux/genhd.h> +#include <linux/highmem.h> +#include <linux/lzo.h> +#include <linux/mutex.h> +#include <linux/proc_fs.h> +#include <linux/swap.h> +#include <linux/tlsf.h> +#include <linux/vmalloc.h> +#include <asm/pgtable.h> +#include <asm/string.h> + +#include "compcache.h" + +static struct block_device_operations compcache_devops = { + .owner = THIS_MODULE, +}; + +static struct compcache compcache; +static unsigned long compcache_size_kbytes; +#if STATS +static struct compcache_stats stats; +#endif + +#ifdef CONFIG_COMPCACHE_PROC +static struct proc_dir_entry *proc; + +static int proc_compcache_read(char *page, char **start, off_t off, + int count, int *eof, void *data) +{ + int len; +#if STATS + size_t succ_writes; + unsigned int good_compress_perc = 0, no_compress_perc = 0; +#endif + + if (off > 0) { + *eof = 1; + return 0; + } + + len = sprintf(page, + "DiskSize: %8u kB\n", + compcache.size >> (10 - SECTOR_SHIFT)); +#if STATS + succ_writes = stats.num_writes - stats.failed_writes; + if (succ_writes) { + good_compress_perc = stats.good_compress * 100 / succ_writes; + no_compress_perc = stats.pages_expand * 100 / succ_writes; + } + + len += sprintf(page + len, + "NumReads: %8u\n" + "NumWrites: %8u\n" + "FailedReads: %8u\n" + "FailedWrites: %8u\n" + "InvalidIO: %8u\n" + "GoodCompress: %8u %%\n" + "NoCompress: %8u %%\n" + "CurrentPages: %8zu\n" + "CurrentMem: %8zu kB\n" + "PeakMem: %8zu kB\n", + stats.num_reads, + stats.num_writes, + stats.failed_reads, + stats.failed_writes, + stats.invalid_io, + good_compress_perc, + no_compress_perc, + stats.curr_pages, + K(stats.curr_mem), + K(stats.peak_mem)); +#endif + return len; +} +#endif /* CONFIG_COMPCACHE_PROC */ + +/* Check if request is within bounds and page aligned */ +static inline int valid_swap_request(struct bio *bio) +{ + if (unlikely((bio->bi_sector >= compcache.size) || + (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; + return 1; +} + +static int compcache_make_request(struct request_queue *queue, struct bio *bio) +{ + int ret; + size_t clen, page_no; + void *user_mem; + struct page *page; + + if (!valid_swap_request(bio)) { + stat_inc(&stats.invalid_io); + goto out_nomap; + } + + CC_DEBUG2("bio sector: %lu (%s)\n", (unsigned long)bio->bi_sector, + bio_data_dir(bio) == READ ? "R" : "W"); + + page = bio->bi_io_vec[0].bv_page; + page_no = bio->bi_sector >> SECTORS_PER_PAGE_SHIFT; + user_mem = kmap(page); + + if (bio_data_dir(bio) == READ) { + stat_inc(&stats.num_reads); + /* + * This is 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) + */ + if (unlikely(compcache.table[page_no].addr == NULL)) { + CC_DEBUG("Read before write on swap device: " + "sector=%lu, size=%zu, offset=%zu\n", + (unsigned long)(bio->bi_sector), + bio->bi_size, + bio->bi_io_vec[0].bv_offset); + memset(user_mem, 0, PAGE_SIZE); + kunmap(page); + set_bit(BIO_UPTODATE, &bio->bi_flags); + bio_endio(bio, 0); + return 0; + } + + /* Page is stored uncompressed since its incompressible */ + if (unlikely(compcache.table[page_no].len == PAGE_SIZE)) { + memcpy(user_mem, compcache.table[page_no].addr, + PAGE_SIZE); + kunmap(page); + set_bit(BIO_UPTODATE, &bio->bi_flags); + bio_endio(bio, 0); + return 0; + } + + clen = PAGE_SIZE; + ret = lzo1x_decompress_safe( + compcache.table[page_no].addr, + compcache.table[page_no].len, + user_mem, + &clen); + + /* should NEVER happen */ + if (unlikely(ret != LZO_E_OK)) { + pr_err(C "Decompression failed! " + "err=%d, page=%zu, len=%u\n", ret, page_no, + compcache.table[page_no].len); + stat_inc(&stats.failed_reads); + goto out; + } + + CC_DEBUG2("Page decompressed: page_no=%zu\n", page_no); + kunmap(page); + set_bit(BIO_UPTODATE, &bio->bi_flags); + bio_endio(bio, 0); + return 0; + } else { /* Write */ + unsigned char *src = "" + stat_inc(&stats.num_writes); + /* + * 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 (compcache.table[page_no].addr) { + CC_DEBUG2("Freeing page: %zu\n", page_no); + tlsf_free(compcache.table[page_no].addr, + compcache.mem_pool); + stat_dec(&stats.curr_pages); + compcache.table[page_no].addr = NULL; + compcache.table[page_no].len = 0; + } + + mutex_lock(&compcache.lock); + ret = lzo1x_1_compress(user_mem, PAGE_SIZE, + src, &clen, compcache.compress_workmem); + if (unlikely(ret != LZO_E_OK)) { + mutex_unlock(&compcache.lock); + pr_err(C "Compression failed! err=%d\n", ret); + compcache.table[page_no].addr = NULL; + compcache.table[page_no].len = 0; + stat_inc(&stats.failed_writes); + goto out; + } + + /* Page is incompressible - store it as is */ + if (clen >= PAGE_SIZE) { + CC_DEBUG("Page expand on compression: " + "page=%zu, size=%zu\n", page_no, clen); + clen = PAGE_SIZE; + src = "" + } else { + CC_DEBUG2("Page compressed: page_no=%zu, len=%zu\n", + page_no, clen); + } + if ((compcache.table[page_no].addr = tlsf_malloc(clen, + compcache.mem_pool)) == NULL) { + mutex_unlock(&compcache.lock); + pr_err(C "Error allocating memory for compressed " + "page: %zu, size=%zu \n", page_no, clen); + compcache.table[page_no].len = 0; + stat_inc(&stats.failed_writes); + goto out; + } + + memcpy(compcache.table[page_no].addr, src, clen); + + /* Update stats */ + stat_inc(&stats.curr_pages); + stat_set(&stats.curr_mem, stats.curr_mem + clen); + stat_setmax(&stats.peak_mem, stats.curr_mem); + stat_inc_if_less(&stats.pages_expand, PAGE_SIZE - 1, clen); + stat_inc_if_less(&stats.good_compress, clen, + PAGE_SIZE / 2 + 1); + mutex_unlock(&compcache.lock); + + compcache.table[page_no].len = clen; + + kunmap(page); + set_bit(BIO_UPTODATE, &bio->bi_flags); + bio_endio(bio, 0); + return 0; + } +out: + kunmap(page); +out_nomap: + bio_io_error(bio); + return 0; +} + +static void setup_swap_header(union swap_header *s) +{ + s->info.version = 1; + s->info.last_page = compcache.size >> SECTORS_PER_PAGE_SHIFT; + s->info.nr_badpages = 0; + memcpy(s->magic.magic, "SWAPSPACE2", 10); +} + +static void *get_mem(size_t size) +{ + return __vmalloc(size, GFP_NOIO, PAGE_KERNEL); +} + +static void put_mem(void *ptr) +{ + vfree(ptr); +} + +static int __init compcache_init(void) +{ + int ret; + size_t num_pages; + struct sysinfo i; + + mutex_init(&compcache.lock); + + if (compcache_size_kbytes == 0) { + pr_info(C "compcache size not provided." + " Using default: (%u%% of Total RAM).\n" + "Use compcache_size_kbytes module param to specify" + " custom size\n", DEFAULT_COMPCACHE_PERCENT); + si_meminfo(&i); + compcache_size_kbytes = ((DEFAULT_COMPCACHE_PERCENT * + i.totalram) / 100) << (PAGE_SHIFT - 10); + } + + CC_DEBUG2("compcache_size_kbytes=%lu\n", compcache_size_kbytes); + compcache.size = compcache_size_kbytes << 10; + compcache.size = (compcache.size + PAGE_SIZE - 1) & PAGE_MASK; + pr_info(C "Compressed swap size set to: %zu KB\n", compcache.size >> 10); + compcache.size >>= SECTOR_SHIFT; + + compcache.compress_workmem = kmalloc(LZO1X_MEM_COMPRESS, GFP_KERNEL); + if (compcache.compress_workmem == NULL) { + pr_err(C "Error allocating compressor working memory\n"); + ret = -ENOMEM; + goto fail; + } + + compcache.compress_buffer = kmalloc(2 * PAGE_SIZE, GFP_KERNEL); + if (compcache.compress_buffer == NULL) { + pr_err(C "Error allocating compressor buffer space\n"); + ret = -ENOMEM; + goto fail; + } + + num_pages = compcache.size >> SECTORS_PER_PAGE_SHIFT; + compcache.table = vmalloc(num_pages * sizeof(*compcache.table)); + if (compcache.table == NULL) { + pr_err(C "Error allocating compcache address table\n"); + ret = -ENOMEM; + goto fail; + } + memset(compcache.table, 0, num_pages * sizeof(*compcache.table)); + + compcache.table[0].addr = (void *)get_zeroed_page(GFP_KERNEL); + if (compcache.table[0].addr == NULL) { + pr_err(C "Error allocating swap header page\n"); + ret = -ENOMEM; + goto fail; + } + compcache.table[0].len = PAGE_SIZE; + setup_swap_header((union swap_header *)(compcache.table[0].addr)); + + compcache.disk = alloc_disk(1); + if (compcache.disk == NULL) { + pr_err(C "Error allocating disk structure\n"); + ret = -ENOMEM; + goto fail; + } + + compcache.disk->first_minor = 0; + compcache.disk->fops = &compcache_devops; + /* + * It is named like this to prevent distro installers + * from offering compcache as installation target. They + * seem to ignore all devices beginning with 'ram' + */ + sprintf(compcache.disk->disk_name, "%s", "ramzswap0"); + + compcache.disk->major = register_blkdev(0, compcache.disk->disk_name); + if (compcache.disk->major < 0) { + pr_err(C "Cannot register block device\n"); + ret = -EFAULT; + goto fail; + } + + compcache.disk->queue = blk_alloc_queue(GFP_KERNEL); + if (compcache.disk->queue == NULL) { + pr_err(C "Cannot register disk queue\n"); + ret = -EFAULT; + goto fail; + } + + set_capacity(compcache.disk, compcache.size); + blk_queue_make_request(compcache.disk->queue, compcache_make_request); + blk_queue_hardsect_size(compcache.disk->queue, PAGE_SIZE); + add_disk(compcache.disk); + + compcache.mem_pool = tlsf_create_memory_pool("compcache", + get_mem, put_mem, + INIT_SIZE, 0, GROW_SIZE); + if (compcache.mem_pool == NULL) { + pr_err(C "Error creating memory pool\n"); + ret = -ENOMEM; + goto fail; + } + +#ifdef CONFIG_COMPCACHE_PROC + proc = create_proc_entry("compcache", S_IRUGO, NULL); + if (proc) + proc->read_proc = &proc_compcache_read; + else { + ret = -ENOMEM; + pr_warning(C "Error creating proc entry\n"); + goto fail; + } +#endif + + CC_DEBUG(C "Initialization done!\n"); + return 0; + +fail: + if (compcache.disk != NULL) { + if (compcache.disk->major > 0) + unregister_blkdev(compcache.disk->major, + compcache.disk->disk_name); + del_gendisk(compcache.disk); + } + + if (compcache.table[0].addr) + free_page((unsigned long)compcache.table[0].addr); + if (compcache.compress_workmem) + kfree(compcache.compress_workmem); + if (compcache.compress_buffer) + kfree(compcache.compress_buffer); + if (compcache.table) + vfree(compcache.table); + if (compcache.mem_pool) + tlsf_destroy_memory_pool(compcache.mem_pool); +#ifdef CONFIG_COMPCACHE_PROC + if (proc) + remove_proc_entry("compcache", &proc_root); +#endif + pr_err(C "Initialization failed: err=%d\n", ret); + return ret; +} + +static void __exit compcache_exit(void) +{ + size_t i, num_pages; + num_pages = compcache.size >> SECTORS_PER_PAGE_SHIFT; + + unregister_blkdev(compcache.disk->major, compcache.disk->disk_name); + del_gendisk(compcache.disk); + free_page((unsigned long)compcache.table[0].addr); + kfree(compcache.compress_workmem); + kfree(compcache.compress_buffer); + + /* Free all pages that are still in compcache */ + for (i = 1; i < num_pages; i++) + if (compcache.table[i].addr) + tlsf_free(compcache.table[i].addr, compcache.mem_pool); + vfree(compcache.table); + tlsf_destroy_memory_pool(compcache.mem_pool); + +#ifdef CONFIG_COMPCACHE_PROC + remove_proc_entry("compcache", &proc_root); +#endif + CC_DEBUG("cleanup done!\n"); +} + +module_param(compcache_size_kbytes, ulong, 0); +MODULE_PARM_DESC(compcache_size_kbytes, "compcache device size (in KB)"); + +module_init(compcache_init); +module_exit(compcache_exit); + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Nitin Gupta <nitingupta910 at gmail dot com>"); +MODULE_DESCRIPTION("Compressed RAM Based Swap Device"); -- |
