From: Greg Kroah-Hartman Date: Sun, 16 Jul 2023 08:41:38 +0000 (+0200) Subject: 6.4-stable patches X-Git-Tag: v6.1.39~93 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=69415a422a9947c528ea213a5a2aec4d2378aa3b;p=thirdparty%2Fkernel%2Fstable-queue.git 6.4-stable patches added patches: io_uring-use-io_schedule-in-cqring-wait.patch --- diff --git a/queue-6.4/io_uring-use-io_schedule-in-cqring-wait.patch b/queue-6.4/io_uring-use-io_schedule-in-cqring-wait.patch new file mode 100644 index 00000000000..12d0dff9098 --- /dev/null +++ b/queue-6.4/io_uring-use-io_schedule-in-cqring-wait.patch @@ -0,0 +1,81 @@ +From 8a796565cec3601071cbbd27d6304e202019d014 Mon Sep 17 00:00:00 2001 +From: Andres Freund +Date: Fri, 7 Jul 2023 09:20:07 -0700 +Subject: io_uring: Use io_schedule* in cqring wait + +From: Andres Freund + +commit 8a796565cec3601071cbbd27d6304e202019d014 upstream. + +I observed poor performance of io_uring compared to synchronous IO. That +turns out to be caused by deeper CPU idle states entered with io_uring, +due to io_uring using plain schedule(), whereas synchronous IO uses +io_schedule(). + +The losses due to this are substantial. On my cascade lake workstation, +t/io_uring from the fio repository e.g. yields regressions between 20% +and 40% with the following command: +./t/io_uring -r 5 -X0 -d 1 -s 1 -c 1 -p 0 -S$use_sync -R 0 /mnt/t2/fio/write.0.0 + +This is repeatable with different filesystems, using raw block devices +and using different block devices. + +Use io_schedule_prepare() / io_schedule_finish() in +io_cqring_wait_schedule() to address the difference. + +After that using io_uring is on par or surpassing synchronous IO (using +registered files etc makes it reliably win, but arguably is a less fair +comparison). + +There are other calls to schedule() in io_uring/, but none immediately +jump out to be similarly situated, so I did not touch them. Similarly, +it's possible that mutex_lock_io() should be used, but it's not clear if +there are cases where that matters. + +Cc: stable@vger.kernel.org # 5.10+ +Cc: Pavel Begunkov +Cc: io-uring@vger.kernel.org +Cc: linux-kernel@vger.kernel.org +Signed-off-by: Andres Freund +Link: https://lore.kernel.org/r/20230707162007.194068-1-andres@anarazel.de +[axboe: minor style fixup] +Signed-off-by: Jens Axboe +Signed-off-by: Greg Kroah-Hartman +--- + io_uring/io_uring.c | 15 +++++++++++++-- + 1 file changed, 13 insertions(+), 2 deletions(-) + +--- a/io_uring/io_uring.c ++++ b/io_uring/io_uring.c +@@ -2575,6 +2575,8 @@ int io_run_task_work_sig(struct io_ring_ + static inline int io_cqring_wait_schedule(struct io_ring_ctx *ctx, + struct io_wait_queue *iowq) + { ++ int token, ret; ++ + if (unlikely(READ_ONCE(ctx->check_cq))) + return 1; + if (unlikely(!llist_empty(&ctx->work_llist))) +@@ -2585,11 +2587,20 @@ static inline int io_cqring_wait_schedul + return -EINTR; + if (unlikely(io_should_wake(iowq))) + return 0; ++ ++ /* ++ * Use io_schedule_prepare/finish, so cpufreq can take into account ++ * that the task is waiting for IO - turns out to be important for low ++ * QD IO. ++ */ ++ token = io_schedule_prepare(); ++ ret = 0; + if (iowq->timeout == KTIME_MAX) + schedule(); + else if (!schedule_hrtimeout(&iowq->timeout, HRTIMER_MODE_ABS)) +- return -ETIME; +- return 0; ++ ret = -ETIME; ++ io_schedule_finish(token); ++ return ret; + } + + /* diff --git a/queue-6.4/series b/queue-6.4/series index beeaeefa68f..e07f88dac4b 100644 --- a/queue-6.4/series +++ b/queue-6.4/series @@ -715,3 +715,4 @@ i2c-xiic-don-t-try-to-handle-more-interrupt-events-a.patch writeback-account-the-number-of-pages-written-back.patch lib-dhry-fix-sleeping-allocations-inside-non-preempt.patch revert-drm-amd-display-move-dcn314-domain-power-cont.patch +io_uring-use-io_schedule-in-cqring-wait.patch