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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> ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1662016302; a=rsa-sha256; cv=none; b=RhZ7cUwmk6gdo8sYUbl4PMPoBk8qmgGnerhYBertXREFdReFxBGus6CxH9y2QdY5Q9XZce DTcoIRb5MzB4F8Be7oiUng0mHglz6DTk601RAUo59eL/uweizlZiOGftYydhQii2lygNUy zBU/gnGiY5zkvcEGZi0RGBC4Floosbo= ARC-Authentication-Results: i=1; imf06.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b=neTNuYxo; spf=none (imf06.hostedemail.com: domain of peterz@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=peterz@infradead.org; dmarc=none ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1662016302; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=0alPrNIyXUGsDd/lDjKfjoAzSlLEpkpL3yJZZ94RPpk=; b=vWmYjluHu6PH6pLEtOR9U+uX9Ojusx478gMj9PvEWH1wFKrr7qx7BESemnxfHL15/F+2LL ljhpLNlR6IB5l0H0CG4821MR1D7gOg3A5Ko2Va2vXEzXqYXyHaHFiZGej2quCpcuk8sr7g wsyAuXW+/RKqxMobkdVIK1gpaOshMow= X-Rspam-User: X-Stat-Signature: at9hm4iykbzt3msba1n9zd1rfyaxm9nc X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: D7FEE180044 Authentication-Results: imf06.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b=neTNuYxo; spf=none (imf06.hostedemail.com: domain of peterz@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=peterz@infradead.org; dmarc=none X-HE-Tag: 1662016302-671943 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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?