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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 31787ECAAD1 for ; Thu, 1 Sep 2022 07:13:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233454AbiIAHND (ORCPT ); Thu, 1 Sep 2022 03:13:03 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48034 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233464AbiIAHM5 (ORCPT ); Thu, 1 Sep 2022 03:12:57 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 410751243C1; Thu, 1 Sep 2022 00:11:59 -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=0alPrNIyXUGsDd/lDjKfjoAzSlLEpkpL3yJZZ94RPpk=; b=neTNuYxorlf1E6lqksEri7ob9s +fOEKml0dypX1VPsk71Al83+X/wCWVLA2v8MAkyhFFTF2iv7nIDbg8DLeKDx/Rohb0D/WGiowcdyF 0922P6Ye6aFkRzhuFME6aeUZzKEon4H+p5J4aJUsUfyeUn3pphhfCCpeODAoqUXD8D3vBJsTb3KKg i0elKtC2iCCloFyRF8muS9N3Uom/PTE/NlgZ/EuB/5pL3cvoO8AeT2wg/ELDQb4daJgt/gZxAtlcx +BB0kImmBciB+hA72jxFiegxOnV9t9ymgmWDAn4pa1ntPYvLXdkppEVbVbS9dT3KZirOXj99594dd nqw0a9fg==; Received: from j130084.upc-j.chello.nl ([24.132.130.84] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1oTeMD-005p99-An; Thu, 01 Sep 2022 07:11:21 +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 (4096 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id D2B58300431; Thu, 1 Sep 2022 09:11:17 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id B51EF20981381; Thu, 1 Sep 2022 09:11:17 +0200 (CEST) Date: Thu, 1 Sep 2022 09:11:17 +0200 From: Peter Zijlstra To: Suren Baghdasaryan Cc: akpm@linux-foundation.org, kent.overstreet@linux.dev, mhocko@suse.com, vbabka@suse.cz, hannes@cmpxchg.org, roman.gushchin@linux.dev, mgorman@suse.de, dave@stgolabs.net, willy@infradead.org, liam.howlett@oracle.com, void@manifault.com, juri.lelli@redhat.com, ldufour@linux.ibm.com, peterx@redhat.com, david@redhat.com, axboe@kernel.dk, mcgrof@kernel.org, masahiroy@kernel.org, nathan@kernel.org, changbin.du@intel.com, ytcoode@gmail.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, bristot@redhat.com, vschneid@redhat.com, cl@linux.com, penberg@kernel.org, iamjoonsoo.kim@lge.com, 42.hyeyoo@gmail.com, glider@google.com, elver@google.com, dvyukov@google.com, shakeelb@google.com, songmuchun@bytedance.com, arnd@arndb.de, jbaron@akamai.com, rientjes@google.com, minchan@google.com, kaleshsingh@google.com, kernel-team@android.com, linux-mm@kvack.org, iommu@lists.linux.dev, kasan-dev@googlegroups.com, io-uring@vger.kernel.org, linux-arch@vger.kernel.org, xen-devel@lists.xenproject.org, linux-bcache@vger.kernel.org, linux-modules@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [RFC PATCH 27/30] Code tagging based latency tracking Message-ID: References: <20220830214919.53220-1-surenb@google.com> <20220830214919.53220-28-surenb@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220830214919.53220-28-surenb@google.com> Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org On Tue, Aug 30, 2022 at 02:49:16PM -0700, Suren Baghdasaryan wrote: > From: Kent Overstreet > > This adds the ability to easily instrument code for measuring latency. > To use, add the following to calls to your code, at the start and end of > the event you wish to measure: > > code_tag_time_stats_start(start_time); > code_tag_time_stats_finish(start_time); > > Stastistics will then show up in debugfs under > /sys/kernel/debug/time_stats, listed by file and line number. > > Stastics measured include weighted averages of frequency, duration, max > duration, as well as quantiles. > > This patch also instruments all calls to init_wait and finish_wait, > which includes all calls to wait_event. Example debugfs output: How can't you do this with a simple eBPF script on top of trace_sched_stat_* and friends?