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=-0.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS autolearn=ham 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 A532EC004C9 for ; Sun, 5 May 2019 23:54:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6563E206DF for ; Sun, 5 May 2019 23:54:13 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="Z/uPHszh" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727939AbfEEXyK (ORCPT ); Sun, 5 May 2019 19:54:10 -0400 Received: from mail-io1-f67.google.com ([209.85.166.67]:38601 "EHLO mail-io1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727593AbfEEXyJ (ORCPT ); Sun, 5 May 2019 19:54:09 -0400 Received: by mail-io1-f67.google.com with SMTP id y6so9687283ior.5 for ; Sun, 05 May 2019 16:54:09 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-transfer-encoding:content-language; bh=j3iAXrkonZmZ6s5g4mLaqH7grkCFn9NCr/nHQmcE/Ms=; b=Z/uPHszhv9FeBpTUexI1ln1daNoPISXTPWcICXcKyiq8TMUckRoVSihJViDMMv/ICz 8pEAGPqjlTYCZnBYuIrMNEvD9aTCmuSXYbmdwbaXoV+SxXP7dLkmEm0/YiUWNs4DawT6 TsSYTCGamVZCmRbU3N0p4iJ+qg7Tv/0Q4grFw7UgWuavKbmf0sTFgwwyldwXAzXMkiU6 zVeDjsZ1Xl5iMTnTnjH9pqWXQuJs0YLU/DyTnDAzbWmYrXk+iT0A5KEOZA8Ba3PWKfpQ h89MaImm4CJNrSayJmSKQHV6BjBi3bf16wSIRtkzo9ZClZJHlCtZqUBEWb6eel7iwhYa yBug== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-transfer-encoding :content-language; bh=j3iAXrkonZmZ6s5g4mLaqH7grkCFn9NCr/nHQmcE/Ms=; b=kMJTxUbvu5JMnYXCW7X890H5t3nZ3/Hc401MTW6VkqA8MLviW8ONNb8k2RBEKMc6RD 9KR2ySJ3F7lIeBzdem+SDGCbvW0hEveEJpMS5QHS67SNOIeQfdYmQ/YbKB/3dIFbxVAa YJpobNnSJnEsi5i0sSanVRulMIYkV9gdTLyW4P9lcCTHLjfCeoOjRGEqUSVCgJzevWQE yFmoVAQNKthgxsXEiZAJXTlQ85fEOIKpjp+o024BTG06dpaL+IgC6jAv3rVjcZJ8WXcC M86EBJYVB/wDNxFCup/QUzwKnfShTxgJfdmVrs3/lHQOp0mVrdB53Jl4r7n80NgJ4Qa9 +/Ug== X-Gm-Message-State: APjAAAWdAXQNDtXNLtrHnASrXiQEt6JRM6YPIiusm+xBfCb3ZDdiGket EFM3CHQBdxCBiuu04/hB9bj9eks= X-Google-Smtp-Source: APXvYqzlJjQD31LDWRVhWviklYdwimYOmZ/I1wHKAUBi4N4JUKAGQ3l/NF16/K65AwjukkTAa0qdCw== X-Received: by 2002:a5e:d80a:: with SMTP id l10mr12481212iok.32.1557100448634; Sun, 05 May 2019 16:54:08 -0700 (PDT) Received: from [192.168.1.99] ([92.117.170.52]) by smtp.googlemail.com with ESMTPSA id q207sm4084238itc.37.2019.05.05.16.54.06 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sun, 05 May 2019 16:54:07 -0700 (PDT) Subject: Re: [PATCH v2 1/4] ftrace: Implement fs notification for preempt/irqsoff tracers To: Steven Rostedt Cc: Joel Fernandes , Ingo Molnar , linux-kernel@vger.kernel.org References: <20190504164710.GA55790@google.com> <20190505223915.4569-1-viktor.rosendahl@gmail.com> <20190505190133.49b5ea46@oasis.local.home> From: Viktor Rosendahl Message-ID: Date: Mon, 6 May 2019 01:54:04 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: <20190505190133.49b5ea46@oasis.local.home> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 5/6/19 1:01 AM, Steven Rostedt wrote: > On Mon,  6 May 2019 00:39:15 +0200 > Viktor Rosendahl wrote: > >> Can you explain more precisely what you agree with? >> >> The general idea of being able to trace bursts of latencies? > > One thing I have an issue with the current approach is the use of the > trace file for this. You mean that using fsnotify is kind of okayish but that it's confusing for the user because only a subset of tracers would send the fsnotify event when the trace file is updated? > > Hmm, what about adding a notifier to tracing_max_latency instead? And > do it not as a config option, but have it always enabled. It would send a > notification when it changes, and that only happens when there's a new > max latency. Would that work for you? Yes, it seems to be OK since the tracing_max_latency is updated also with the latest latency that exceeds the threshold when we are using tracing_thresh. I will try to send a new version of the patch series soon, with the modifications that have been discussed so far. best regards, Viktor