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 7ABA9EB64DD for ; Tue, 1 Aug 2023 05:54:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230443AbjHAFx7 (ORCPT ); Tue, 1 Aug 2023 01:53:59 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55598 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229946AbjHAFx6 (ORCPT ); Tue, 1 Aug 2023 01:53:58 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AD98DE7D for ; Mon, 31 Jul 2023 22:53:57 -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 291F86146F for ; Tue, 1 Aug 2023 05:53:57 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2FC50C433C8; Tue, 1 Aug 2023 05:53:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1690869236; bh=WYSWY2rQWISC7pbippvLrt0e6pU9gItTYd33Fd7G5qw=; h=Subject:To:Cc:From:Date:From; b=Gvid/3VtoBbYuN4IYj85OKx2DeztqqRX3nkPtLJoa0VcIkDSl/2WdD/AAPvesbik7 VImkya+dsR81R7UUGXZhJ+QSnstEqiFg5yolaHYm+yWujoXHSM5KOHtKCLWMbh9ILR xqK85XmlpDiPtoiLf2qM+LB/9OBif5vN8IJNWmK0= Subject: FAILED: patch "[PATCH] io_uring: gate iowait schedule on having pending requests" failed to apply to 6.1-stable tree To: axboe@kernel.dk, andres@anarazel.de, oleksandr@natalenko.name, phil@raspberrypi.com Cc: From: Date: Tue, 01 Aug 2023 07:53:53 +0200 Message-ID: <2023080153-turkey-reload-8fa7@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 7b72d661f1f2f950ab8c12de7e2bc48bdac8ed69 # git commit -s git send-email --to '' --in-reply-to '2023080153-turkey-reload-8fa7@gregkh' --subject-prefix 'PATCH 6.1.y' HEAD^.. Possible dependencies: 7b72d661f1f2 ("io_uring: gate iowait schedule on having pending requests") 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 7b72d661f1f2f950ab8c12de7e2bc48bdac8ed69 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Mon, 24 Jul 2023 11:28:17 -0600 Subject: [PATCH] io_uring: gate iowait schedule on having pending requests A previous commit made all cqring waits marked as iowait, as a way to improve performance for short schedules with pending IO. However, for use cases that have a special reaper thread that does nothing but wait on events on the ring, this causes a cosmetic issue where we know have one core marked as being "busy" with 100% iowait. While this isn't a grave issue, it is confusing to users. Rather than always mark us as being in iowait, gate setting of current->in_iowait to 1 by whether or not the waiting task has pending requests. Cc: stable@vger.kernel.org Link: https://lore.kernel.org/io-uring/CAMEGJJ2RxopfNQ7GNLhr7X9=bHXKo+G5OOe0LUq=+UgLXsv1Xg@mail.gmail.com/ Link: https://bugzilla.kernel.org/show_bug.cgi?id=217699 Link: https://bugzilla.kernel.org/show_bug.cgi?id=217700 Reported-by: Oleksandr Natalenko Reported-by: Phil Elwell Tested-by: Andres Freund Fixes: 8a796565cec3 ("io_uring: Use io_schedule* in cqring wait") Signed-off-by: Jens Axboe diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c index 89a611541bc4..f4591b912ea8 100644 --- a/io_uring/io_uring.c +++ b/io_uring/io_uring.c @@ -2493,11 +2493,20 @@ int io_run_task_work_sig(struct io_ring_ctx *ctx) return 0; } +static bool current_pending_io(void) +{ + struct io_uring_task *tctx = current->io_uring; + + if (!tctx) + return false; + return percpu_counter_read_positive(&tctx->inflight); +} + /* when returns >0, the caller should retry */ static inline int io_cqring_wait_schedule(struct io_ring_ctx *ctx, struct io_wait_queue *iowq) { - int token, ret; + int io_wait, ret; if (unlikely(READ_ONCE(ctx->check_cq))) return 1; @@ -2511,17 +2520,19 @@ static inline int io_cqring_wait_schedule(struct io_ring_ctx *ctx, 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. + * Mark us as being in io_wait if we have pending requests, 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(); + io_wait = current->in_iowait; + if (current_pending_io()) + current->in_iowait = 1; ret = 0; if (iowq->timeout == KTIME_MAX) schedule(); else if (!schedule_hrtimeout(&iowq->timeout, HRTIMER_MODE_ABS)) ret = -ETIME; - io_schedule_finish(token); + current->in_iowait = io_wait; return ret; }