From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 51E0BEB64DA for ; Sun, 16 Jul 2023 08:41:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229589AbjGPIl0 (ORCPT ); Sun, 16 Jul 2023 04:41:26 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51020 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229462AbjGPIlZ (ORCPT ); Sun, 16 Jul 2023 04:41:25 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AB627D3 for ; Sun, 16 Jul 2023 01:41:24 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 3F98360C19 for ; Sun, 16 Jul 2023 08:41:24 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 424FEC433C8; Sun, 16 Jul 2023 08:41:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1689496883; bh=OYDyK+R+COpdcDjHUwSPXQaIhwMnX15jBU3dq5tS8lA=; h=Subject:To:Cc:From:Date:From; b=Z/4Afca/30fC35YGVgZ9BcVXMLH8UcKPjQnI1zr0r9LhuKgsVoeXh4zh7jLf2TZIL o988NqZEyLsFGav1+RtpWjcGlQS1H7yTMMsRbgeZ+jm72xfWYcc6aPAp/28zjS+xec /fAHjX8Wzdry6wgV1OReXS65aNxCLYSGOz3PjakA= Subject: FAILED: patch "[PATCH] io_uring: Use io_schedule* in cqring wait" failed to apply to 6.1-stable tree To: andres@anarazel.de, asml.silence@gmail.com, axboe@kernel.dk Cc: From: Date: Sun, 16 Jul 2023 10:41:20 +0200 Message-ID: <2023071620-litigate-debunk-939a@gregkh> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org The patch below does not apply to the 6.1-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.1.y git checkout FETCH_HEAD git cherry-pick -x 8a796565cec3601071cbbd27d6304e202019d014 # git commit -s git send-email --to '' --in-reply-to '2023071620-litigate-debunk-939a@gregkh' --subject-prefix 'PATCH 6.1.y' HEAD^.. Possible dependencies: 8a796565cec3 ("io_uring: Use io_schedule* in cqring wait") d33a39e57768 ("io_uring: keep timeout in io_wait_queue") 46ae7eef44f6 ("io_uring: optimise non-timeout waiting") 846072f16eed ("io_uring: mimimise io_cqring_wait_schedule") 3fcf19d592d5 ("io_uring: parse check_cq out of wq waiting") 12521a5d5cb7 ("io_uring: fix CQ waiting timeout handling") 52ea806ad983 ("io_uring: finish waiting before flushing overflow entries") 35d90f95cfa7 ("io_uring: include task_work run after scheduling in wait for events") 1b346e4aa8e7 ("io_uring: don't check overflow flush failures") a85381d8326d ("io_uring: skip overflow CQE posting for dying ring") thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 8a796565cec3601071cbbd27d6304e202019d014 Mon Sep 17 00:00:00 2001 From: Andres Freund Date: Fri, 7 Jul 2023 09:20:07 -0700 Subject: [PATCH] io_uring: Use io_schedule* in cqring wait 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 diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c index e8096d502a7c..7505de2428e0 100644 --- a/io_uring/io_uring.c +++ b/io_uring/io_uring.c @@ -2489,6 +2489,8 @@ int io_run_task_work_sig(struct io_ring_ctx *ctx) 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))) @@ -2499,11 +2501,20 @@ static inline int io_cqring_wait_schedule(struct io_ring_ctx *ctx, 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; } /*