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authorAnand Avati <avati@redhat.com>2013-07-19 08:31:41 -0700
committerVijay Bellur <vbellur@redhat.com>2013-07-23 06:11:12 -0700
commit37ac6bdca826046cbcb0d50727af29baf9407950 (patch)
treeb899eb81a70c7719c5d7e4328697cc314da24b97 /xlators/storage/posix/src/posix-helpers.c
parentcee1f9b5c7917bba220f1156b342bf07cac4ad38 (diff)
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 <avati@redhat.com> Reviewed-on: http://review.gluster.org/4746 Tested-by: Gluster Build System <jenkins@build.gluster.com> Reviewed-by: Vijay Bellur <vbellur@redhat.com>
Diffstat (limited to 'xlators/storage/posix/src/posix-helpers.c')
-rw-r--r--xlators/storage/posix/src/posix-helpers.c140
1 files changed, 140 insertions, 0 deletions
diff --git a/xlators/storage/posix/src/posix-helpers.c b/xlators/storage/posix/src/posix-helpers.c
index a13e0207808..0c0fdbabc96 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 <sys/syscall.h>
+#include <unistd.h>
+ 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;
+ }
+ }
+}