From 1af240f3b51c080376bb6ae1efc13d62b087b65d Mon Sep 17 00:00:00 2001 From: Alexander Motin Date: Wed, 13 Mar 2019 15:00:10 -0400 Subject: [PATCH] Add separate aggregation limit for non-rotating media Before sequential scrub patches ZFS never aggregated I/Os above 128KB. Sequential scrub bumped that to 1MB, supposedly to reduce number of head seeks for spinning disks. But for SSDs it makes little to no sense, especially on FreeBSD, where due to MAXPHYS limitation device will likely still see bunch of 128KB I/Os instead of one large. Having more strict aggregation limit for SSDs allows to avoid allocation of large memory buffer and copy to/from it, that is a serious problem when throughput reaches gigabytes per second. Reviewed-by: Brian Behlendorf Reviewed-by: Richard Elling Signed-off-by: Alexander Motin Closes #8494 --- man/man5/zfs-module-parameters.5 | 11 +++++++++++ module/zfs/vdev_queue.c | 11 ++++++++++- 2 files changed, 21 insertions(+), 1 deletion(-) diff --git a/man/man5/zfs-module-parameters.5 b/man/man5/zfs-module-parameters.5 index 2a0f5f81d..f75f09917 100644 --- a/man/man5/zfs-module-parameters.5 +++ b/man/man5/zfs-module-parameters.5 @@ -2364,6 +2364,17 @@ Default value: \fB5\fR. .RS 12n Max vdev I/O aggregation size .sp +Default value: \fB1,048,576\fR. +.RE + +.sp +.ne 2 +.na +\fBzfs_vdev_aggregation_limit_non_rotating\fR (int) +.ad +.RS 12n +Max vdev I/O aggregation size for non-rotating media +.sp Default value: \fB131,072\fR. .RE diff --git a/module/zfs/vdev_queue.c b/module/zfs/vdev_queue.c index 939699cb8..a1861d5f0 100644 --- a/module/zfs/vdev_queue.c +++ b/module/zfs/vdev_queue.c @@ -174,6 +174,7 @@ int zfs_vdev_async_write_active_max_dirty_percent = 60; * they aren't able to help us aggregate at this level. */ int zfs_vdev_aggregation_limit = 1 << 20; +int zfs_vdev_aggregation_limit_non_rotating = SPA_OLD_MAXBLOCKSIZE; int zfs_vdev_read_gap_limit = 32 << 10; int zfs_vdev_write_gap_limit = 4 << 10; @@ -549,7 +550,11 @@ vdev_queue_aggregate(vdev_queue_t *vq, zio_t *zio) abd_t *abd; maxblocksize = spa_maxblocksize(vq->vq_vdev->vdev_spa); - limit = MAX(MIN(zfs_vdev_aggregation_limit, maxblocksize), 0); + if (vq->vq_vdev->vdev_nonrot) + limit = zfs_vdev_aggregation_limit_non_rotating; + else + limit = zfs_vdev_aggregation_limit; + limit = MAX(MIN(limit, maxblocksize), 0); if (zio->io_flags & ZIO_FLAG_DONT_AGGREGATE || limit == 0) return (NULL); @@ -913,6 +918,10 @@ vdev_queue_last_offset(vdev_t *vd) module_param(zfs_vdev_aggregation_limit, int, 0644); MODULE_PARM_DESC(zfs_vdev_aggregation_limit, "Max vdev I/O aggregation size"); +module_param(zfs_vdev_aggregation_limit_non_rotating, int, 0644); +MODULE_PARM_DESC(zfs_vdev_aggregation_limit_non_rotating, + "Max vdev I/O aggregation size for non-rotating media"); + module_param(zfs_vdev_read_gap_limit, int, 0644); MODULE_PARM_DESC(zfs_vdev_read_gap_limit, "Aggregate read I/O over gap"); -- 2.40.0