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From: Pavel Begunkov <[email protected]>
To: [email protected]
Cc: Jens Axboe <[email protected]>, [email protected]
Subject: [PATCH 0/3] optimise submit+iopoll mutex locking
Date: Tue, 22 Mar 2022 14:07:55 +0000	[thread overview]
Message-ID: <[email protected]> (raw)

This saves one mutex lock/unlock pair per syscall when users do
submit + getevents. Perf tells that for QD1 iopoll this patch reduces overhead
on locking from ~4.3% to ~2.6%, iow cuts 1.3% - 1.9% of CPU time. Something
similar I see in final throughput.

It's a good win for smaller QD, especially considering that io_uring only
takes about 20-30% of all cycles, the rest goes to syscalling, the block
layer and below.

Pavel Begunkov (3):
  io_uring: split off IOPOLL argument verifiction
  io_uring: pre-calculate syscall iopolling decision
  io_uring: optimise mutex locking for submit+iopoll

 fs/io_uring.c | 86 +++++++++++++++++++++++++++++++++------------------
 1 file changed, 56 insertions(+), 30 deletions(-)

-- 
2.35.1



             reply	other threads:[~2022-03-22 14:09 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-03-22 14:07 Pavel Begunkov [this message]
2022-03-22 14:07 ` [PATCH 1/3] io_uring: split off IOPOLL argument verifiction Pavel Begunkov
2022-03-22 14:07 ` [PATCH 2/3] io_uring: pre-calculate syscall iopolling decision Pavel Begunkov
2022-03-22 14:07 ` [PATCH 3/3] io_uring: optimise mutex locking for submit+iopoll Pavel Begunkov

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