From a8b2e30685c9214ccfd0181977540e080340df4e Mon Sep 17 00:00:00 2001 From: Tom Caputi Date: Thu, 21 Dec 2017 12:13:06 -0500 Subject: Support re-prioritizing asynchronous prefetches When sequential scrubs were merged, all calls to arc_read() (including prefetch IOs) were given ZIO_PRIORITY_ASYNC_READ. Unfortunately, this behaves badly with an existing issue where prefetch IOs cannot be re-prioritized after the issue. The result is that synchronous reads end up in the same vdev_queue as the scrub IOs and can have (in some workloads) multiple seconds of latency. This patch incorporates 2 changes. The first ensures that all scrub IOs are given ZIO_PRIORITY_SCRUB to allow the vdev_queue code to differentiate between these I/Os and user prefetches. Second, this patch introduces zio_change_priority() to provide the missing capability to upgrade a zio's priority. Reviewed by: George Wilson Reviewed-by: Brian Behlendorf Signed-off-by: Tom Caputi Closes #6921 Closes #6926 --- include/sys/arc_impl.h | 1 + include/sys/trace_arc.h | 2 +- include/sys/vdev.h | 1 + include/sys/zio.h | 2 ++ 4 files changed, 5 insertions(+), 1 deletion(-) (limited to 'include/sys') diff --git a/include/sys/arc_impl.h b/include/sys/arc_impl.h index e39cf6a8f..a923449d9 100644 --- a/include/sys/arc_impl.h +++ b/include/sys/arc_impl.h @@ -98,6 +98,7 @@ struct arc_callback { boolean_t acb_noauth; uint64_t acb_dsobj; zio_t *acb_zio_dummy; + zio_t *acb_zio_head; arc_callback_t *acb_next; }; diff --git a/include/sys/trace_arc.h b/include/sys/trace_arc.h index 74a76520d..c40b58e32 100644 --- a/include/sys/trace_arc.h +++ b/include/sys/trace_arc.h @@ -108,7 +108,7 @@ DEFINE_ARC_BUF_HDR_EVENT(zfs_arc__evict); DEFINE_ARC_BUF_HDR_EVENT(zfs_arc__delete); DEFINE_ARC_BUF_HDR_EVENT(zfs_new_state__mru); DEFINE_ARC_BUF_HDR_EVENT(zfs_new_state__mfu); -DEFINE_ARC_BUF_HDR_EVENT(zfs_arc__sync__wait__for__async); +DEFINE_ARC_BUF_HDR_EVENT(zfs_arc__async__upgrade__sync); DEFINE_ARC_BUF_HDR_EVENT(zfs_arc__demand__hit__predictive__prefetch); DEFINE_ARC_BUF_HDR_EVENT(zfs_l2arc__hit); DEFINE_ARC_BUF_HDR_EVENT(zfs_l2arc__miss); diff --git a/include/sys/vdev.h b/include/sys/vdev.h index 473d2691c..bc2f4f0ea 100644 --- a/include/sys/vdev.h +++ b/include/sys/vdev.h @@ -123,6 +123,7 @@ extern void vdev_queue_init(vdev_t *vd); extern void vdev_queue_fini(vdev_t *vd); extern zio_t *vdev_queue_io(zio_t *zio); extern void vdev_queue_io_done(zio_t *zio); +extern void vdev_queue_change_io_priority(zio_t *zio, zio_priority_t priority); extern int vdev_queue_length(vdev_t *vd); extern uint64_t vdev_queue_last_offset(vdev_t *vd); diff --git a/include/sys/zio.h b/include/sys/zio.h index 1f9f48268..8beea7adf 100644 --- a/include/sys/zio.h +++ b/include/sys/zio.h @@ -586,6 +586,8 @@ extern void zio_vdev_io_bypass(zio_t *zio); extern void zio_vdev_io_reissue(zio_t *zio); extern void zio_vdev_io_redone(zio_t *zio); +extern void zio_change_priority(zio_t *pio, zio_priority_t priority); + extern void zio_checksum_verified(zio_t *zio); extern int zio_worst_error(int e1, int e2); -- cgit v1.2.3