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=-2.3 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT 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 6F93FC43219 for ; Tue, 30 Apr 2019 09:10:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3A1EC20652 for ; Tue, 30 Apr 2019 09:10:41 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="A6FUcOdL" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726852AbfD3JKk (ORCPT ); Tue, 30 Apr 2019 05:10:40 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:40248 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726129AbfD3JKj (ORCPT ); Tue, 30 Apr 2019 05:10:39 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.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:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=FCg9Iuj2GiaMMZAu3B04tO6kqMZ7lIOz4uSh53rMBAE=; b=A6FUcOdLNxyLVFxNBpkU9U3dh qJurdGp+bC7rIXgoiIg9+uxSDBm1bjWgOxh+mlJXipXDPmSgKNia1xepITpCZWgG3J+lI7qiNBrAm x7ihriPNWhjxMRz0y4tjs2ahP0bvj9UHld0NXOSpZSz+PzATtiUBNnP4eqSLvp8dKthitMRz6ONDo NZRSBTYTLU0RQqCpFzB2BJStzOg0XGcJce1fwwTjd0uloqC4sR21WwnD1qfkbiNMTL6eTUbZ4Eqn9 L6y1O7RfpGh/0j6QTdJ07QPpH9CgcorTWEJWZE3F3d1Zndv5M6E01bFLRX5ab89hsfEss/C/YDlQg ttcravoUA==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1hLOmY-0000eT-ND; Tue, 30 Apr 2019 09:10:34 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 3B2EF29A242E4; Tue, 30 Apr 2019 11:10:33 +0200 (CEST) Date: Tue, 30 Apr 2019 11:10:33 +0200 From: Peter Zijlstra To: Feng Tang Cc: Andrew Morton , Arjan van de Ven , Jonathan Corbet , Ingo Molnar , Eric W Biederman , Dmitry Vyukov , Thomas Gleixner , Andy Lutomirski , Ying Huang , linux-kernel@vger.kernel.org Subject: Re: [RFC PATCH 0/3] latencytop lock usage improvement Message-ID: <20190430091033.GN2623@hirez.programming.kicks-ass.net> References: <1556525011-28022-1-git-send-email-feng.tang@intel.com> <20190430080910.GI2623@hirez.programming.kicks-ass.net> <20190430083505.n5mozwybbnwydo3z@shbuild888> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190430083505.n5mozwybbnwydo3z@shbuild888> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Apr 30, 2019 at 04:35:05PM +0800, Feng Tang wrote: > Hi Peter, > > On Tue, Apr 30, 2019 at 10:09:10AM +0200, Peter Zijlstra wrote: > > On Mon, Apr 29, 2019 at 04:03:28PM +0800, Feng Tang wrote: > > > Hi All, > > > > > > latencytop is a very nice tool for tracing system latency hotspots, and > > > we heavily use it in our LKP test suites. > > > > What data does latency-top give that perf cannot give you? Ideally we'd > > remove latencytop entirely. > > Thanks for the review. In 0day/LKP test service, we have many tools for > monitoring and analyzing the test results, perf is the most important > one, which has the most parts in our auto-generated comparing results. > For example to identify spinlock contentions and system hotspots. > > latencytop is another tool we used to find why systems go idle, like why > workload chose to sleep or waiting for something. You're not answering the question; why can't you use perf for that? ISTR we explicitly added support for things like that.