From be04c14a1bd262a49e5764e5cf864259b7e740fd Mon Sep 17 00:00:00 2001
From: Mike Snitzer <snitzer@kernel.org>
Date: Wed, 14 Jun 2023 21:47:46 -0400
Subject: [PATCH] dm: use op specific max_sectors when splitting abnormal io
Split abnormal IO in terms of the corresponding operation specific
max_sectors (max_discard_sectors, max_secure_erase_sectors or
max_write_zeroes_sectors).
This fixes a significant dm-thinp discard performance regression that
was introduced with commit e2dd8aca2d76 ("dm bio prison v1: improve
concurrent IO performance"). Relative to discard: max_discard_sectors
is used instead of max_sectors; which fixes excessive discard splitting
(e.g. max_sectors=128K vs max_discard_sectors=64M).
Tested by discarding an 1 Petabyte dm-thin device:
lvcreate -V 1125899906842624B -T test/pool -n thin
time blkdiscard /dev/test/thin
Before this fix (splitting discards every 128K): ~116m
After this fix (splitting discards every 64M) : 0m33.460s
Reported-by: Zorro Lang <zlang@redhat.com>
Fixes: 06961c487a33 ("dm: split discards further if target sets max_discard_granularity")
Requires: 13f6facf3fae ("dm: allow targets to require splitting WRITE_ZEROES and SECURE_ERASE")
Fixes: e2dd8aca2d76 ("dm bio prison v1: improve concurrent IO performance")
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
---
drivers/md/dm.c | 25 ++++++++++++++++---------
1 file changed, 16 insertions(+), 9 deletions(-)
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 8488547fc00d3..fffb0cbe2ac8a 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -1172,7 +1172,8 @@ static inline sector_t max_io_len_target_boundary(struct dm_target *ti,
}
static sector_t __max_io_len(struct dm_target *ti, sector_t sector,
- unsigned int max_granularity)
+ unsigned int max_granularity,
+ unsigned int max_sectors)
{
sector_t target_offset = dm_target_offset(ti, sector);
sector_t len = max_io_len_target_boundary(ti, target_offset);
@@ -1186,13 +1187,13 @@ static sector_t __max_io_len(struct dm_target *ti, sector_t sector,
if (!max_granularity)
return len;
return min_t(sector_t, len,
- min(queue_max_sectors(ti->table->md->queue),
+ min(max_sectors ? : queue_max_sectors(ti->table->md->queue),
blk_chunk_sectors_left(target_offset, max_granularity)));
}
static inline sector_t max_io_len(struct dm_target *ti, sector_t sector)
{
- return __max_io_len(ti, sector, ti->max_io_len);
+ return __max_io_len(ti, sector, ti->max_io_len, 0);
}
int dm_set_target_max_io_len(struct dm_target *ti, sector_t len)
@@ -1581,12 +1582,13 @@ static void __send_empty_flush(struct clone_info *ci)
static void __send_changing_extent_only(struct clone_info *ci, struct dm_target *ti,
unsigned int num_bios,
- unsigned int max_granularity)
+ unsigned int max_granularity,
+ unsigned int max_sectors)
{
unsigned int len, bios;
len = min_t(sector_t, ci->sector_count,
- __max_io_len(ti, ci->sector, max_granularity));
+ __max_io_len(ti, ci->sector, max_granularity, max_sectors));
atomic_add(num_bios, &ci->io->io_count);
bios = __send_duplicate_bios(ci, ti, num_bios, &len);
@@ -1623,23 +1625,27 @@ static blk_status_t __process_abnormal_io(struct clone_info *ci,
{
unsigned int num_bios = 0;
unsigned int max_granularity = 0;
+ unsigned int max_sectors = 0;
struct queue_limits *limits = dm_get_queue_limits(ti->table->md);
switch (bio_op(ci->bio)) {
case REQ_OP_DISCARD:
num_bios = ti->num_discard_bios;
+ max_sectors = limits->max_discard_sectors;
if (ti->max_discard_granularity)
- max_granularity = limits->max_discard_sectors;
+ max_granularity = max_sectors;
break;
case REQ_OP_SECURE_ERASE:
num_bios = ti->num_secure_erase_bios;
+ max_sectors = limits->max_secure_erase_sectors;
if (ti->max_secure_erase_granularity)
- max_granularity = limits->max_secure_erase_sectors;
+ max_granularity = max_sectors;
break;
case REQ_OP_WRITE_ZEROES:
num_bios = ti->num_write_zeroes_bios;
+ max_sectors = limits->max_write_zeroes_sectors;
if (ti->max_write_zeroes_granularity)
- max_granularity = limits->max_write_zeroes_sectors;
+ max_granularity = max_sectors;
break;
default:
break;
@@ -1654,7 +1660,8 @@ static blk_status_t __process_abnormal_io(struct clone_info *ci,
if (unlikely(!num_bios))
return BLK_STS_NOTSUPP;
- __send_changing_extent_only(ci, ti, num_bios, max_granularity);
+ __send_changing_extent_only(ci, ti, num_bios,
+ max_granularity, max_sectors);
return BLK_STS_OK;
}
--
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