From 37ac6bdca826046cbcb0d50727af29baf9407950 Mon Sep 17 00:00:00 2001 From: Anand Avati Date: Fri, 19 Jul 2013 08:31:41 -0700 Subject: storage/posix: implement batched fsync in a single thread Because of the extra fsync()s issued by AFR transaction, they could potentially "clog" all the io-threads denying unrelated operations from making progress. This patch assigns a dedicated thread to issues fsyncs, as an experimental feature to understand performance characteristics with the approach. As a basis, incoming individual fsync requests are grouped into batches, falling in the same @batch-fsync-delay-usec window of time. These windows can extend in practice, as processing of the previous batch can take longer than @batch-fsync-delay-usec while new requests are getting batched. The feature support three modes (similar to the -S modes of fs_mark) - syncfs: In this mode one syncfs() is issued per batch, instead of N fsync()s (one per file.) - syncfs-single-fsync: In this mode one syncfs() is issued per batch (which, on Linux, guarantees the completion of write-out of dirty pages in the filesystem up to that point) and one single fsync() to synchronize or flush the controller/drive cache. This corresponds to -S 2 of fsmark. - syncfs-reverse-fsync: In this mode, one syncfs() is issued per batch, and all the open files in that batch are fsync()'ed in the reverse order of the queue. This corresponds to -S 4 of fsmark. - reverse-fsync: In this mode, no syncfs() is issued and all the files in the batch are fsync()'ed in the reverse order. This corresponds to -S 3 of fsmark. Change-Id: Ia1e170a810c780c8d80e02cf910accc4170c4cd4 BUG: 927146 Signed-off-by: Anand Avati Reviewed-on: http://review.gluster.org/4746 Tested-by: Gluster Build System Reviewed-by: Vijay Bellur --- xlators/storage/posix/src/posix-helpers.c | 140 ++++++++++++++++++++++++++++++ 1 file changed, 140 insertions(+) (limited to 'xlators/storage/posix/src/posix-helpers.c') diff --git a/xlators/storage/posix/src/posix-helpers.c b/xlators/storage/posix/src/posix-helpers.c index a13e0207..0c0fdbab 100644 --- a/xlators/storage/posix/src/posix-helpers.c +++ b/xlators/storage/posix/src/posix-helpers.c @@ -1177,3 +1177,143 @@ posix_spawn_health_check_thread (xlator_t *xl) unlock: UNLOCK (&priv->lock); } + +int +posix_fsyncer_pick (xlator_t *this, struct list_head *head) +{ + struct posix_private *priv = NULL; + int count = 0; + + priv = this->private; + pthread_mutex_lock (&priv->fsync_mutex); + { + while (list_empty (&priv->fsyncs)) + pthread_cond_wait (&priv->fsync_cond, + &priv->fsync_mutex); + + count = priv->fsync_queue_count; + priv->fsync_queue_count = 0; + list_splice_init (&priv->fsyncs, head); + } + pthread_mutex_unlock (&priv->fsync_mutex); + + return count; +} + + +void +posix_fsyncer_process (xlator_t *this, call_stub_t *stub, gf_boolean_t do_fsync) +{ + struct posix_fd *pfd = NULL; + int ret = -1; + struct posix_private *priv = NULL; + + priv = this->private; + + ret = posix_fd_ctx_get (stub->args.fd, this, &pfd); + if (ret < 0) { + gf_log (this->name, GF_LOG_ERROR, + "could not get fdctx for fd(%s)", + uuid_utoa (stub->args.fd->inode->gfid)); + call_unwind_error (stub, -1, EINVAL); + return; + } + + if (do_fsync) { +#ifdef HAVE_FDATASYNC + if (stub->args.datasync) + ret = fdatasync (pfd->fd); + else +#endif + ret = fsync (pfd->fd); + } else { + ret = 0; + } + + if (ret) { + gf_log (this->name, GF_LOG_ERROR, + "could not fstat fd(%s)", + uuid_utoa (stub->args.fd->inode->gfid)); + call_unwind_error (stub, -1, errno); + return; + } + + call_unwind_error (stub, 0, 0); +} + + +static void +posix_fsyncer_syncfs (xlator_t *this, struct list_head *head) +{ + call_stub_t *stub = NULL; + struct posix_fd *pfd = NULL; + int ret = -1; + + stub = list_entry (head->prev, call_stub_t, list); + ret = posix_fd_ctx_get (stub->args.fd, this, &pfd); + if (ret) + return; + +#ifdef GF_LINUX_HOST_OS + /* syncfs() is not "declared" in RHEL's glibc even though + the kernel has support. + */ +#include +#include + syscall (SYS_syncfs, pfd->fd); +#else + sync(); +#endif + +} + + +void * +posix_fsyncer (void *d) +{ + xlator_t *this = d; + struct posix_private *priv = NULL; + call_stub_t *stub = NULL; + call_stub_t *tmp = NULL; + struct list_head list; + int count = 0; + gf_boolean_t do_fsync = _gf_true; + + priv = this->private; + + for (;;) { + INIT_LIST_HEAD (&list); + + count = posix_fsyncer_pick (this, &list); + + usleep (priv->batch_fsync_delay_usec); + + gf_log (this->name, GF_LOG_DEBUG, + "picked %d fsyncs", count); + + switch (priv->batch_fsync_mode) { + case BATCH_NONE: + case BATCH_REVERSE_FSYNC: + break; + case BATCH_SYNCFS: + case BATCH_SYNCFS_SINGLE_FSYNC: + case BATCH_SYNCFS_REVERSE_FSYNC: + posix_fsyncer_syncfs (this, &list); + break; + } + + if (priv->batch_fsync_mode == BATCH_SYNCFS) + do_fsync = _gf_false; + else + do_fsync = _gf_true; + + list_for_each_entry_safe_reverse (stub, tmp, &list, list) { + list_del_init (&stub->list); + + posix_fsyncer_process (this, stub, do_fsync); + + if (priv->batch_fsync_mode == BATCH_SYNCFS_SINGLE_FSYNC) + do_fsync = _gf_false; + } + } +} -- cgit