On 10/27/21 15:02, Hao Xu wrote:
Tested this patchset by manually replace __io_queue_sqe() in
io_queue_sqe() by io_req_task_queue() to construct 'heavy' task works.
Then test with fio:
If submissions and completions are done by the same task it doesn't
really matter in which order they're executed because the task won't
get back to userspace execution to see CQEs until tw returns.
Furthermore, it even might be worse because the earlier you submit
the better with everything else equal.
IIRC, that's how it's with fio, right? If so, you may get better
numbers with a test that does submissions and completions in
different threads.
Also interesting to find an explanation for you numbers assuming
they're stable. 7/8 batching? How often it does it go this path?
If only one task submits requests it should already be covered
with existing batching.
ioengine=io_uring
sqpoll=1
thread=1
bs=4k
direct=1
rw=randread
time_based=1
runtime=600
randrepeat=0
group_reporting=1
filename=/dev/nvme0n1
2/8 set unlimited priority_task_list, 8/8 set a limitation of
1/3 * (len_prority_list + len_normal_list), data below:
depth no 8/8 include 8/8 before this patchset
1 7.05 7.82 7.10
2 8.47 8.48 8.60
4 10.42 9.99 10.42
8 13.78 13.13 13.22
16 27.41 27.92 24.33
32 49.40 46.16 53.08
64 102.53 105.68 103.36
128 196.98 202.76 205.61
256 372.99 375.61 414.88
512 747.23 763.95 791.30
1024 1472.59 1527.46 1538.72
2048 3153.49 3129.22 3329.01
4096 6387.86 5899.74 6682.54
8192 12150.25 12433.59 12774.14
16384 23085.58 24342.84 26044.71
It seems 2/8 is better, haven't tried other choices other than 1/3,
still put 8/8 here for people's further thoughts.
Hao Xu (8):
io-wq: add helper to merge two wq_lists
io_uring: add a priority tw list for irq completion work
io_uring: add helper for task work execution code
io_uring: split io_req_complete_post() and add a helper
io_uring: move up io_put_kbuf() and io_put_rw_kbuf()
io_uring: add nr_ctx to record the number of ctx in a task
io_uring: batch completion in prior_task_list
io_uring: add limited number of TWs to priority task list
fs/io-wq.h | 21 +++++++
fs/io_uring.c | 168 +++++++++++++++++++++++++++++++++++---------------
2 files changed, 138 insertions(+), 51 deletions(-)
--
Pavel Begunkov
