From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp.codeaurora.org by pdx-caf-mail.web.codeaurora.org (Dovecot) with LMTP id ma00D+1WGVsadAAAmS7hNA ; Thu, 07 Jun 2018 16:01:49 +0000 Received: by smtp.codeaurora.org (Postfix, from userid 1000) id 782116090E; Thu, 7 Jun 2018 16:01:48 +0000 (UTC) Authentication-Results: smtp.codeaurora.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="BI0M9bFG" X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on pdx-caf-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-10.5 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,T_DKIMWL_WL_MED, USER_IN_DEF_DKIM_WL autolearn=ham autolearn_force=no version=3.4.0 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by smtp.codeaurora.org (Postfix) with ESMTP id BFE9F60590; Thu, 7 Jun 2018 16:01:46 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org BFE9F60590 Authentication-Results: pdx-caf-mail.web.codeaurora.org; dmarc=fail (p=reject dis=none) header.from=google.com Authentication-Results: pdx-caf-mail.web.codeaurora.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934187AbeFGQBo (ORCPT + 25 others); Thu, 7 Jun 2018 12:01:44 -0400 Received: from mail-wr0-f196.google.com ([209.85.128.196]:41004 "EHLO mail-wr0-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932912AbeFGQBc (ORCPT ); Thu, 7 Jun 2018 12:01:32 -0400 Received: by mail-wr0-f196.google.com with SMTP id h10-v6so10399311wrq.8 for ; Thu, 07 Jun 2018 09:01:32 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=GzoDECv4OvkI9xX9WzUiTmYqSn3LavsRzoEt3FCoFNI=; b=BI0M9bFGcMuixuYOFkCfnF6MllMwseNI1WAo21DYJFzgRKjdRp8lQVbJKm1h4qFGIg 0A7oUWZaG0qFeVJd6BcCfb6f8VTOXGfNoHJ9YIhk4KMa2jZndzlsg3OnaQZRKdwtrRXN y1vd19A2jxLSt5hHEO1dSkiK3v7dwxmEFavfdOeaHquQiyGXd7+FRdPPcXnl//rFsURu 44iP0POD5+eyUwiJLTAR1Yr0g8cG1I9gvyBb+tJCJkyGfs1F3XTIK3kojif/kn+PlJXE d1y/SpZ5jTtcs7t6UI2aMwTlwsUGpOZzPgGtRgm/5dGk3kFBo7gNM6Nx5iazrWEHGxgZ xOVg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=GzoDECv4OvkI9xX9WzUiTmYqSn3LavsRzoEt3FCoFNI=; b=SI2Jzye1XgR0ADqxeA+z7KajBJw5rTp19FMOmXDq1RyLleFUndAmsNV7fGEv3xaBEV Of3yscmyb2BYgmblwt14mm1AR51OPUvPSoRv94nOYYCSDq9yPlAMjanswxyzBoqNB/ov yjaPPSyA1GeZW2KT/FWoJQ9Fyi93qYa6M7P8cxjYgjk3gJ1e9DpF9PVhDeX/hUD8E237 X5XwvxIuxxEQjq2/5d/s5Y+9dSW3Qb1Dy3k317SuYauUIe6en/z4bLVccCAdvhiEZyk0 lGIRWivA/49nR7O/U9oHRuYZkYLkQnl+ueJ/GDm/TDqQFuli1DkOuH7PLVVchsvTWhK3 dtog== X-Gm-Message-State: APt69E25q3zLIKrlVlVURpOzHjfd3t4nyJwmJoCHCny35wqTrtHA30WW zPp0X8Eun6Exg5mdlcTqe1qDlyNmxru6fR295Q749A== X-Google-Smtp-Source: ADUXVKLA7JymL97kNx5B1VfssJZL/2t5pQ98LULpLj5rv5WEX4RpmtBwsuAYZBp9dbxQOVy+grSYwFsFmMCVj8IDHE8= X-Received: by 2002:adf:b839:: with SMTP id h54-v6mr2313882wrf.36.1528387291581; Thu, 07 Jun 2018 09:01:31 -0700 (PDT) MIME-Version: 1.0 References: <20180606221513.11302-1-jolsa@kernel.org> <20180606221513.11302-10-jolsa@kernel.org> <20180607154522.hyjmxn3q6zgcvsnx@two.firstfloor.org> In-Reply-To: <20180607154522.hyjmxn3q6zgcvsnx@two.firstfloor.org> From: Stephane Eranian Date: Thu, 7 Jun 2018 09:01:30 -0700 Message-ID: Subject: Re: [PATCH 09/10] perf/cputime: Don't stop idle tick if there's live cputime event To: Andi Kleen Cc: Jiri Olsa , Arnaldo Carvalho de Melo , Peter Zijlstra , LKML , Ingo Molnar , Namhyung Kim , David Ahern , Alexander Shishkin , Milian Wolff , frederic@kernel.org Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Jiri, On Thu, Jun 7, 2018 at 8:45 AM Andi Kleen wrote: > > On Thu, Jun 07, 2018 at 12:15:12AM +0200, Jiri Olsa wrote: > > Disable stopping of the idle tick when having live cputime > > event. When the tick is disabled, the idle counts are out > > of date until next tick/update and perf cputime PMU provides > > misleading counts. > > I really don't like this. This can totally change performance > (e.g. less Turbo due to less idle) and performance tools shouldn't > change the performance profile drastically. > You do not want to change the behavior of the kernel just because you are monitoring. This may introduce side effects on other events which may not otherwise exist.