diff options
author | Jeff Moyer <jmoyer@redhat.com> | 2009-10-02 18:57:36 -0400 |
---|---|---|
committer | Jens Axboe <jens.axboe@oracle.com> | 2009-10-28 09:29:25 +0100 |
commit | cfb1e33eed48165763edc7a4a067cf5f74898d0b (patch) | |
tree | d0e0bdd0664615b1f7be6cf770476e16dbcad116 | |
parent | 1af60fbd759d31f565552fea315c2033947cfbe6 (diff) |
aio: implement request batching
Hi,
Some workloads issue batches of small I/O, and the performance is poor
due to the call to blk_run_address_space for every single iocb. Nathan
Roberts pointed this out, and suggested that by deferring this call
until all I/Os in the iocb array are submitted to the block layer, we
can realize some impressive performance gains (up to 30% for sequential
4k reads in batches of 16).
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
-rw-r--r-- | fs/aio.c | 61 | ||||
-rw-r--r-- | fs/direct-io.c | 8 |
2 files changed, 63 insertions, 6 deletions
@@ -32,6 +32,9 @@ #include <linux/workqueue.h> #include <linux/security.h> #include <linux/eventfd.h> +#include <linux/blkdev.h> +#include <linux/mempool.h> +#include <linux/hash.h> #include <asm/kmap_types.h> #include <asm/uaccess.h> @@ -60,6 +63,14 @@ static DECLARE_WORK(fput_work, aio_fput_routine); static DEFINE_SPINLOCK(fput_lock); static LIST_HEAD(fput_head); +#define AIO_BATCH_HASH_BITS 3 /* allocated on-stack, so don't go crazy */ +#define AIO_BATCH_HASH_SIZE (1 << AIO_BATCH_HASH_BITS) +struct aio_batch_entry { + struct hlist_node list; + struct address_space *mapping; +}; +mempool_t *abe_pool; + static void aio_kick_handler(struct work_struct *); static void aio_queue_work(struct kioctx *); @@ -73,6 +84,8 @@ static int __init aio_setup(void) kioctx_cachep = KMEM_CACHE(kioctx,SLAB_HWCACHE_ALIGN|SLAB_PANIC); aio_wq = create_workqueue("aio"); + abe_pool = mempool_create_kmalloc_pool(1, sizeof(struct aio_batch_entry)); + BUG_ON(!abe_pool); pr_debug("aio_setup: sizeof(struct page) = %d\n", (int)sizeof(struct page)); @@ -1531,8 +1544,44 @@ static int aio_wake_function(wait_queue_t *wait, unsigned mode, return 1; } +static void aio_batch_add(struct address_space *mapping, + struct hlist_head *batch_hash) +{ + struct aio_batch_entry *abe; + struct hlist_node *pos; + unsigned bucket; + + bucket = hash_ptr(mapping, AIO_BATCH_HASH_BITS); + hlist_for_each_entry(abe, pos, &batch_hash[bucket], list) { + if (abe->mapping == mapping) + return; + } + + abe = mempool_alloc(abe_pool, GFP_KERNEL); + BUG_ON(!igrab(mapping->host)); + abe->mapping = mapping; + hlist_add_head(&abe->list, &batch_hash[bucket]); + return; +} + +static void aio_batch_free(struct hlist_head *batch_hash) +{ + struct aio_batch_entry *abe; + struct hlist_node *pos, *n; + int i; + + for (i = 0; i < AIO_BATCH_HASH_SIZE; i++) { + hlist_for_each_entry_safe(abe, pos, n, &batch_hash[i], list) { + blk_run_address_space(abe->mapping); + iput(abe->mapping->host); + hlist_del(&abe->list); + mempool_free(abe, abe_pool); + } + } +} + static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb, - struct iocb *iocb) + struct iocb *iocb, struct hlist_head *batch_hash) { struct kiocb *req; struct file *file; @@ -1608,6 +1657,12 @@ static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb, ; } spin_unlock_irq(&ctx->ctx_lock); + if (req->ki_opcode == IOCB_CMD_PREAD || + req->ki_opcode == IOCB_CMD_PREADV || + req->ki_opcode == IOCB_CMD_PWRITE || + req->ki_opcode == IOCB_CMD_PWRITEV) + aio_batch_add(file->f_mapping, batch_hash); + aio_put_req(req); /* drop extra ref to req */ return 0; @@ -1635,6 +1690,7 @@ SYSCALL_DEFINE3(io_submit, aio_context_t, ctx_id, long, nr, struct kioctx *ctx; long ret = 0; int i; + struct hlist_head batch_hash[AIO_BATCH_HASH_SIZE] = { { 0, }, }; if (unlikely(nr < 0)) return -EINVAL; @@ -1666,10 +1722,11 @@ SYSCALL_DEFINE3(io_submit, aio_context_t, ctx_id, long, nr, break; } - ret = io_submit_one(ctx, user_iocb, &tmp); + ret = io_submit_one(ctx, user_iocb, &tmp, batch_hash); if (ret) break; } + aio_batch_free(batch_hash); put_ioctx(ctx); return i ? i : ret; diff --git a/fs/direct-io.c b/fs/direct-io.c index c86d35f142de..3af761c8c5cc 100644 --- a/fs/direct-io.c +++ b/fs/direct-io.c @@ -1028,9 +1028,6 @@ direct_io_worker(int rw, struct kiocb *iocb, struct inode *inode, if (dio->bio) dio_bio_submit(dio); - /* All IO is now issued, send it on its way */ - blk_run_address_space(inode->i_mapping); - /* * It is possible that, we return short IO due to end of file. * In that case, we need to release all the pages we got hold on. @@ -1057,8 +1054,11 @@ direct_io_worker(int rw, struct kiocb *iocb, struct inode *inode, ((rw & READ) || (dio->result == dio->size))) ret = -EIOCBQUEUED; - if (ret != -EIOCBQUEUED) + if (ret != -EIOCBQUEUED) { + /* All IO is now issued, send it on its way */ + blk_run_address_space(inode->i_mapping); dio_await_completion(dio); + } /* * Sync will always be dropping the final ref and completing the |