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 CF332C00144 for ; Mon, 1 Aug 2022 13:26:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230428AbiHAN0r (ORCPT ); Mon, 1 Aug 2022 09:26:47 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58022 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230527AbiHAN0p (ORCPT ); Mon, 1 Aug 2022 09:26:45 -0400 Received: from mail-ed1-x52b.google.com (mail-ed1-x52b.google.com [IPv6:2a00:1450:4864:20::52b]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EBB503C8C0 for ; Mon, 1 Aug 2022 06:26:43 -0700 (PDT) Received: by mail-ed1-x52b.google.com with SMTP id e15so13711351edj.2 for ; Mon, 01 Aug 2022 06:26:43 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=eFCO67CpyQ/ZoV+dmJNx2L2eUcdu4y5M0dyI0OTIEDY=; b=UhDkpJjAC4BCDAq74QHc1BiI0XDgJ17/KMUeveF/ZZz7SRmKlNeg9vtLTLyujrkxKH GF6db9PuaIHeAR5MAakqw2dFIWs/OZO2UFxrRIsCRk1WS4uSMdPRzRLEMBPx9iExAgXa j2Ceb8VcmmtpZoV+L0kx2Dbo/UoERRcbzbBO/SmDBCj+3/5derJ/XadOtSkmgSWQn7sO DcExW7Slr50teMWJ2GApCuBr/nlYv8WNXGGOCrcFUZPnou3M5kU0Fn0qGdfB8wCEx/7m znl84YUATJbUP1xupKhhpvf0lOXThBVdnxxphAr1HI5XWvIU3PFb6Km36c3dTD82tYtc 3TZA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:sender:date:from:to:cc:subject:message-id :references:mime-version:content-disposition:in-reply-to; bh=eFCO67CpyQ/ZoV+dmJNx2L2eUcdu4y5M0dyI0OTIEDY=; b=zzXfpF4NJerRqUxUn6riMKwTpi2KVRmMvlbhSrsrOP86LxX7/cxsrBCzHQ/3b3cFdj gwB0zPfz/57e7uxRlGK9ForhnFLQFcMiN0HIGITY2cXsX23ioi16i96fpPPqdFi/Uhls Zj7lDVbsJRIVXhNGxWC0zESBFrB8UCdcxQBOzQKqI60cWO8uqpvtOXm+O+qD+AmHKYT/ qEw8c6/t8Umk5jxs9nknvhWQGSZ0yDdLtr+BIRk1OlHtYQOpSa9iI+WDteVBMPp9FTeC UOj/FxCDYu6vKJuoAdtEdriDYvu73FEeHKPZKE7edxRzF6UN4sH4ClVd+rK7Q7jR5klW KJow== X-Gm-Message-State: AJIora/XHzFaLCvreWJZsRWmkAbwk+POC1/xy3VnVT/7jLjG81zMoIWz ZVmj42DaN90zgKof5TaednY= X-Google-Smtp-Source: AGRyM1t6dzKgKfq+Y2k9dzSbNjAPihFk4OlSQkX0WKngVL/mVAo4Ix7juuIjJKrGYTjbfqtzwwxFeg== X-Received: by 2002:aa7:dc12:0:b0:43b:5d77:f0b with SMTP id b18-20020aa7dc12000000b0043b5d770f0bmr16015672edu.37.1659360402178; Mon, 01 Aug 2022 06:26:42 -0700 (PDT) Received: from gmail.com (84-236-113-167.pool.digikabel.hu. [84.236.113.167]) by smtp.gmail.com with ESMTPSA id o17-20020a170906769100b007308bdef04bsm970959ejm.103.2022.08.01.06.26.41 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 01 Aug 2022 06:26:41 -0700 (PDT) Sender: Ingo Molnar Date: Mon, 1 Aug 2022 15:26:39 +0200 From: Ingo Molnar To: K Prateek Nayak Cc: Libo Chen , peterz@infradead.org, vincent.guittot@linaro.org, mgorman@suse.de, tim.c.chen@linux.intel.com, 21cnbao@gmail.com, dietmar.eggemann@arm.com, linux-kernel@vger.kernel.org, tglx@linutronix.de Subject: Re: [PATCH] sched/fair: no sync wakeup from interrupt context Message-ID: References: <20220711224704.1672831-1-libo.chen@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * K Prateek Nayak wrote: > Hello Libo and Peter, > > tl;dr > > - We observed a major regression with tbench when testing the latest tip > sched/core at: > commit 14b3f2d9ee8d "sched/fair: Disallow sync wakeup from interrupt context" > Reason for the regression are the fewer affine wakeups that leaves the > client farther away from the data it needs to consume next primed in the > waker's LLC. > Such regressions can be expected from tasks that use sockets to communicate > significant amount of data especially on system with multiple LLCs. > > - Other benchmarks have a comparable behavior to the tip at previous commit > commit : 91caa5ae2424 "sched/core: Fix the bug that task won't enqueue > into core tree when update cookie" > > I'll leave more details below. Mel Gorman also warned about this negative side-effect in: Subject: Re: [PATCH] sched/fair: no sync wakeup from interrupt context Date: Fri, 15 Jul 2022 11:07:38 +0100 Message-ID: <20220715100738.GD3493@suse.de> https://lore.kernel.org/all/20220715100738.GD3493@suse.de/ I've reverted this commit (14b3f2d9ee8df3b) for the time being from tip:sched/core. Thanks for the heads-up! Thanks, Ingo