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=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 22723C43460 for ; Wed, 12 May 2021 11:40:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E50D9613CF for ; Wed, 12 May 2021 11:40:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230326AbhELLlt (ORCPT ); Wed, 12 May 2021 07:41:49 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52350 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230300AbhELLlr (ORCPT ); Wed, 12 May 2021 07:41:47 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6AC1EC061574; Wed, 12 May 2021 04:40:39 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=hfpiF6M7gD0zv0WKuJyv2m+M6IsU8UI95/eFQuGgu0c=; b=cqybAHBnHGa7VYS1KWnAIjqRbz gs9rJ56mJD0juvKQQXZWweMK7GN0n6rj0SLu1aRsjlkkkdKDwEpwfworFPum7WVo7R9QKUUqw+qxZ rOEmhftRvA3iktdWOJBViKYPdR1XwZTzDeESI/QkjkXP1et0Rad9Ye5n+NwtbwySaAFORwDpV5LYA FfURIykhTRfwfWtYAFrFytQfCKgpTAwyHvrDiSUcNvfMKqMI1zf7oK7syrCfdehJAqUanyhYFVRpu KvvkUhLdkDJuqifNGrVI39R99ndUyoUbr5DViph62fYNPujCg93A0bRf1jTSkWHCKst/SeUH1tPLc mU6gZTpw==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.94 #2 (Red Hat Linux)) id 1lgnBh-008E6B-0N; Wed, 12 May 2021 11:38:09 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 6905F300242; Wed, 12 May 2021 13:38:00 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 4A14420C6A1CF; Wed, 12 May 2021 13:38:00 +0200 (CEST) Date: Wed, 12 May 2021 13:38:00 +0200 From: Peter Zijlstra To: Mel Gorman Cc: Balbir Singh , tglx@linutronix.de, mingo@kernel.org, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, bristot@redhat.com, pbonzini@redhat.com, maz@kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, riel@surriel.com, hannes@cmpxchg.org, Paul Wise Subject: Re: [PATCH 0/6] sched,delayacct: Some cleanups Message-ID: References: <20210505105940.190490250@infradead.org> <20210505222940.GA4236@balbir-desktop> <20210507123810.GB4236@balbir-desktop> <20210512113419.GF3672@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210512113419.GF3672@suse.de> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, May 12, 2021 at 12:34:19PM +0100, Mel Gorman wrote: > > I don't disagree, we've had these around for a while and I know of users > > that use these stats to find potential starvation. I am OK with default > > disabled. I suspect distros will have the final say. > > > > I think default disabled should be fine. At worst when dealing with a bug > there would be a need to either reboot or enable at runtime with patch > 7 included and add that instruction to the bug report when requesting > iotop data. At worst, a distro could revert the patch if iotop generated > too many bug reports or patch iotop in the distro package. > > Alternatively, I've added Paul Wise to the cc who is the latest > committer to iotop. Maybe he knows who could add/commit a check for > sysctl.sched_delayacct and if it exists then check if it's 1 and display > an error suggesting corrective action (add delayacct to the kernel command > line or sysctl sched.sched_delayacct=1). iotop appears to be in maintenance > mode but gets occasional commits even if it has not had a new version > since 2013 so maybe it could get a 0.7 tag if such a check was added. In the final commit I made the knob be known as task_delayacct. I figured that was a slightly better name. But yes, a check in iotop, if that really is the sole user of all this, would be very nice. Thanks!