[lustre-devel] [PATCH 15/25] lustre: osc: Improve osc_queue_sync_pages
James Simmons
jsimmons at infradead.org
Mon Aug 2 12:50:35 PDT 2021
From: Patrick Farrell <farr0186 at gmail.com>
This patch was split and partially done in:
https://review.whamcloud.com/38214
So the text below refers to the combination of this patch
and that one. This patch now just improves a looped atomic
add by replacing with a single one. The rest of the grant
calcuation change is in
https://review.whamcloud.com/38214
(I am retaining the text below to show the performance
improvement)
----------
osc_queue_sync_pages now has a grant calculation component,
this has a pretty painful impact on the new faster DIO
performance. Specifically, per page ktime_get() and the
per-page atomic_add cost close to 10% of total CPU time in
the DIO path.
We can make this per batch of pages rather than for each
page, which reduces this cost from 10% of CPU to almost
nothing.
This improves write performance by about 10% (but has no
effect on reads, since they don't use grant).
This patch reduces i/o time in ms/GiB by:
Write: 10 ms/GiB
Read: 0 ms/GiB
Totals:
Write: 158 ms/GiB
Read: 161 ms/GiB
mpirun -np 1 $IOR -w -t 1G -b 64G -o $FILE --posix.odirect
Before patch:
write 6071
After patch:
write 6470
(Read is similar.)
This also fixes a mistake in d23d4cb67c / LU-13419 where it
removed the shrink interval update entirely from the direct
i/o path.
Fixes: d23d4cb67c ("lustre: osc: Move shrink update to per-write")
WC-bug-id: https://jira.whamcloud.com/browse/LU-13419
Lustre-commit: 87c4535f7a5d239a ("LU-13799 osc: Improve osc_queue_sync_pages")
Signed-off-by: Patrick Farrell <farr0186 at gmail.com>
Reviewed-on: https://review.whamcloud.com/39482
Reviewed-by: Andreas Dilger <adilger at whamcloud.com>
Reviewed-by: Wang Shilong <wshilong at whamcloud.com>
Reviewed-by: Oleg Drokin <green at whamcloud.com>
Signed-off-by: James Simmons <jsimmons at infradead.org>
---
fs/lustre/osc/osc_cache.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/fs/lustre/osc/osc_cache.c b/fs/lustre/osc/osc_cache.c
index 50f6477..69cf9ba 100644
--- a/fs/lustre/osc/osc_cache.c
+++ b/fs/lustre/osc/osc_cache.c
@@ -2715,8 +2715,8 @@ int osc_queue_sync_pages(const struct lu_env *env, struct cl_io *io,
list_for_each_entry(oap, list, oap_pending_item) {
osc_consume_write_grant(cli,
&oap->oap_brw_page);
- atomic_long_inc(&obd_dirty_pages);
}
+ atomic_long_add(page_count, &obd_dirty_pages);
osc_unreserve_grant_nolock(cli, grants, 0);
ext->oe_grants = grants;
} else {
@@ -2730,6 +2730,7 @@ int osc_queue_sync_pages(const struct lu_env *env, struct cl_io *io,
"not enough grant available, switching to sync for this i/o\n");
}
spin_unlock(&cli->cl_loi_list_lock);
+ osc_update_next_shrink(cli);
}
ext->oe_is_rdma_only = !!(brw_flags & OBD_BRW_RDMA_ONLY);
--
1.8.3.1
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