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From: Hao Xu <[email protected]>
To: [email protected]
Cc: Jens Axboe <[email protected]>,
	Pavel Begunkov <[email protected]>,
	Joseph Qi <[email protected]>
Subject: [PATCH 0/3] decouple work_list protection from the big wqe->lock
Date: Sun,  6 Feb 2022 17:52:38 +0800	[thread overview]
Message-ID: <[email protected]> (raw)

wqe->lock is abused, it now protects acct->work_list, hash stuff,
nr_workers, wqe->free_list and so on. Lets first get the work_list out
of the wqe-lock mess by introduce a specific lock for work list. This
is the first step to solve the huge contension between work insertion
and work consumption.
good thing:
  - split locking for bound and unbound work list
  - reduce contension between work_list visit and (worker's)free_list.

For the hash stuff, since there won't be a work with same file in both
bound and unbound work list, thus they won't visit same hash entry. it
works well to use the new lock to protect hash stuff.

Results:
set max_unbound_worker = 4, test with echo-server:
nice -n -15 ./io_uring_echo_server -p 8081 -f -n 1000 -l 16
(-n connection, -l workload)
before this patch:
Samples: 2M of event 'cycles:ppp', Event count (approx.): 1239982111074
Overhead  Command          Shared Object         Symbol
  28.59%  iou-wrk-10021    [kernel.vmlinux]      [k] native_queued_spin_lock_slowpath
   8.89%  io_uring_echo_s  [kernel.vmlinux]      [k] native_queued_spin_lock_slowpath
   6.20%  iou-wrk-10021    [kernel.vmlinux]      [k] _raw_spin_lock
   2.45%  io_uring_echo_s  [kernel.vmlinux]      [k] io_prep_async_work
   2.36%  iou-wrk-10021    [kernel.vmlinux]      [k] _raw_spin_lock_irqsave
   2.29%  iou-wrk-10021    [kernel.vmlinux]      [k] io_worker_handle_work
   1.29%  io_uring_echo_s  [kernel.vmlinux]      [k] io_wqe_enqueue
   1.06%  iou-wrk-10021    [kernel.vmlinux]      [k] io_wqe_worker
   1.06%  io_uring_echo_s  [kernel.vmlinux]      [k] _raw_spin_lock
   1.03%  iou-wrk-10021    [kernel.vmlinux]      [k] __schedule
   0.99%  iou-wrk-10021    [kernel.vmlinux]      [k] tcp_sendmsg_locked

with this patch:
Samples: 1M of event 'cycles:ppp', Event count (approx.): 708446691943
Overhead  Command          Shared Object         Symbol
  16.86%  iou-wrk-10893    [kernel.vmlinux]      [k] native_queued_spin_lock_slowpat
   9.10%  iou-wrk-10893    [kernel.vmlinux]      [k] _raw_spin_lock
   4.53%  io_uring_echo_s  [kernel.vmlinux]      [k] native_queued_spin_lock_slowpat
   2.87%  iou-wrk-10893    [kernel.vmlinux]      [k] io_worker_handle_work
   2.57%  iou-wrk-10893    [kernel.vmlinux]      [k] _raw_spin_lock_irqsave
   2.56%  io_uring_echo_s  [kernel.vmlinux]      [k] io_prep_async_work
   1.82%  io_uring_echo_s  [kernel.vmlinux]      [k] _raw_spin_lock
   1.33%  iou-wrk-10893    [kernel.vmlinux]      [k] io_wqe_worker
   1.26%  io_uring_echo_s  [kernel.vmlinux]      [k] try_to_wake_up

spin_lock failure from 25.59% + 8.89% =  34.48% to 16.86% + 4.53% = 21.39%
TPS is similar, while cpu usage is from almost 400% to 350%


Hao Xu (3):
  io-wq: decouple work_list protection from the big wqe->lock
  io-wq: reduce acct->lock crossing functions lock/unlock
  io-wq: use IO_WQ_ACCT_NR rather than hardcoded number

 fs/io-wq.c | 114 ++++++++++++++++++++++++++---------------------------
 1 file changed, 57 insertions(+), 57 deletions(-)


base-commit: f6133fbd373811066c8441737e65f384c8f31974
-- 
2.25.1


             reply	other threads:[~2022-02-06  9:52 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-02-06  9:52 Hao Xu [this message]
2022-02-06  9:52 ` [PATCH 1/3] io-wq: decouple work_list protection from the big wqe->lock Hao Xu
2022-02-06  9:52 ` [PATCH 2/3] io-wq: reduce acct->lock crossing functions lock/unlock Hao Xu
2022-02-06  9:52 ` [PATCH 3/3] io-wq: use IO_WQ_ACCT_NR rather than hardcoded number Hao Xu
2022-02-11 16:55 ` [PATCH 0/3] decouple work_list protection from the big wqe->lock Jens Axboe
2022-02-14 17:18   ` Hao Xu
2022-02-11 16:56 ` Jens Axboe

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