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 X-Spam-Level: X-Spam-Status: No, score=-2.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7CE5BC43460 for ; Wed, 5 May 2021 22:29:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5DDE2611AD for ; Wed, 5 May 2021 22:29:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230376AbhEEWap (ORCPT ); Wed, 5 May 2021 18:30:45 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60968 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229712AbhEEWao (ORCPT ); Wed, 5 May 2021 18:30:44 -0400 Received: from mail-pj1-x102d.google.com (mail-pj1-x102d.google.com [IPv6:2607:f8b0:4864:20::102d]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 499B5C061574; Wed, 5 May 2021 15:29:46 -0700 (PDT) Received: by mail-pj1-x102d.google.com with SMTP id k3-20020a17090ad083b0290155b934a295so2030670pju.2; Wed, 05 May 2021 15:29:46 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=znkSlKiu5G4Hhz1MTty3vtN5arr0IksFQo0x+yCPNiQ=; b=A06CrOWSPs6ckpXv/wQSHMTR3zY8KGTeP8ajN3gPgEXLAnD4baUlbo2tOmbst/P6zB YJ9z87LdCXVkKL8K9516HUr1ourWZ7hlB80DWGDuCwUX0lSItL/wgqCv9Sr5VSzlifJQ Q3xYzcyD9N/3LQ+C4zSnl/x+sHzNtM88N/e2mqv9zAtbErimtL9e1PTacXA0GaLnY667 pSunaCRyx8ZOnmgssvUTKaRGxCOmqnsXDVRKOGC5IbcC+Ey+iKPota/d+gZentrNo0V1 ZEswHrYFF86CkZiUK8s9zJtZghvMn0PVpRpsV8Ykw16OnUpcjalz8M9fezu6ny9qwBIR ceVQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=znkSlKiu5G4Hhz1MTty3vtN5arr0IksFQo0x+yCPNiQ=; b=YEuFpTunhAdoiTsTP5OSrEHFcesQ0f5ecNyumyfYqUab7VX0pupqlhh391TCMQ+4XH QhTihvDViy3N/sCMZ9YnnSQw9agjghI+pzRzdRHA/F6rWsYjy2ByP9Qj6M/D1R4NReCl xUDRi/dJxa+cHUBNOXGPYY2foymAAslhFVIhgzG7FVFUx2ZdetHuKWJOuXdCzvyvBEcD iv3ufKLJHY6ORx4NimhQQVyPw61ID6gIyrW4Pa0UZK3fgfod/fyxUy8kGZDGGlIT0LBu P6EAvJs4xaB/jTudVz42pAii2WrZPukXmF4rPX3XSkdnztm34/gGv9NXkiCMvtVnE2hr d7aw== X-Gm-Message-State: AOAM530dz5xfctPJz0Xm82xddGdswZbFegXyWqBmkvT9fNMLcZP6Bw3b Bw6NmgUS4EUFYnELbrVaP5oGhp8sJ8tTTQNouhw= X-Google-Smtp-Source: ABdhPJznH2+IA2bFYDzVaGRKaWpOyUl5ObnhphhBf1Q+pjimtm+Ke/a5BKVRSEdB+0iwYKrM7XeZ1w== X-Received: by 2002:a17:902:c3c5:b029:ed:3ff4:70f3 with SMTP id j5-20020a170902c3c5b02900ed3ff470f3mr1415607plj.12.1620253785609; Wed, 05 May 2021 15:29:45 -0700 (PDT) Received: from localhost ([203.87.99.126]) by smtp.gmail.com with ESMTPSA id z16sm8080223pjq.42.2021.05.05.15.29.43 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 05 May 2021 15:29:44 -0700 (PDT) Date: Thu, 6 May 2021 08:29:40 +1000 From: Balbir Singh To: Peter Zijlstra Cc: tglx@linutronix.de, mingo@kernel.org, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, bristot@redhat.com, pbonzini@redhat.com, maz@kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, riel@surriel.com, hannes@cmpxchg.org Subject: Re: [PATCH 0/6] sched,delayacct: Some cleanups Message-ID: <20210505222940.GA4236@balbir-desktop> References: <20210505105940.190490250@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210505105940.190490250@infradead.org> Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Wed, May 05, 2021 at 12:59:40PM +0200, Peter Zijlstra wrote: > Hi, > > Due to: > > https://lkml.kernel.org/r/0000000000001d43ac05c0f5c6a0@google.com > > and general principle, delayacct really shouldn't be using ktime (pvclock also > really shouldn't be doing what it does, but that's another story). This lead me > to looking at the SCHED_INFO, SCHEDSTATS, DELAYACCT (and PSI) accounting hell. > > The rest of the patches are an attempt at simplifying all that a little. All > that crud is enabled by default for distros which is leading to a death by a > thousand cuts. > > The last patch is an attempt at default disabling DELAYACCT, because I don't > think anybody actually uses that much, but what do I know, there were no ill > effects on my testbox. Perhaps we should mirror > /proc/sys/kernel/sched_schedstats and provide a delayacct sysctl for runtime > frobbing. > There are tools like iotop that use delayacct to display information. When the code was checked in, we did run SPEC* back in the day 2006 to find overheads, nothing significant showed. Do we have any date on the overhead your seeing? I'll look at the patches Balbir Singh.