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 55AC5C6FA82 for ; Fri, 2 Sep 2022 01:59:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232014AbiIBB7E (ORCPT ); Thu, 1 Sep 2022 21:59:04 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60514 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229839AbiIBB7E (ORCPT ); Thu, 1 Sep 2022 21:59:04 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D3516A98F4; Thu, 1 Sep 2022 18:59:02 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 8C6ACB8298F; Fri, 2 Sep 2022 01:59:01 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 171BAC433C1; Fri, 2 Sep 2022 01:58:53 +0000 (UTC) Date: Thu, 1 Sep 2022 21:59:25 -0400 From: Steven Rostedt To: Kent Overstreet Cc: Suren Baghdasaryan , akpm@linux-foundation.org, 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, peterz@infradead.org, 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, 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: <20220901215925.59ae5cb0@gandalf.local.home> In-Reply-To: <20220902013532.6n5cyf3oofntljho@moria.home.lan> References: <20220830214919.53220-1-surenb@google.com> <20220830214919.53220-28-surenb@google.com> <20220901173844.36e1683c@gandalf.local.home> <20220901215438.gy3bgqa4ghhm6ztm@moria.home.lan> <20220901183430.120311ce@gandalf.local.home> <20220901225515.ogg7pyljmfzezamr@moria.home.lan> <20220901202311.546a53b5@gandalf.local.home> <20220902013532.6n5cyf3oofntljho@moria.home.lan> X-Mailer: Claws Mail 3.17.8 (GTK+ 2.24.33; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org On Thu, 1 Sep 2022 21:35:32 -0400 Kent Overstreet wrote: > On Thu, Sep 01, 2022 at 08:23:11PM -0400, Steven Rostedt wrote: > > If ftrace, perf, bpf can't do what you want, take a harder look to see if > > you can modify them to do so. > > Maybe we can use this exchange to make both of our tools better. I like your > histograms - the quantiles algorithm I've had for years is janky, I've been > meaning to rip that out, I'd love to take a look at your code for that. And > having an on/off switch is a good idea, I'll try to add that at some point. > Maybe you got some ideas from my stuff too. > > I'd love to get better tracepoints for measuring latency - what I added to > init_wait() and finish_wait() was really only a starting point. Figuring out > the right places to measure is where I'd like to be investing my time in this > area, and there's no reason we couldn't both be making use of that. Yes, this is exactly what I'm talking about. I'm not against your work, I just want you to work more with everyone to come up with ideas that can help everyone as a whole. That's how "open source communities" is suppose to work ;-) The histogram and synthetic events can use some more clean ups. There's a lot of places that can be improved in that code. But I feel the ideas behind that code is sound. It's just getting the implementation to be a bit more efficient. > > e.g. with kernel waitqueues, I looked at hooking prepare_to_wait() first but not > all code uses that, init_wait() got me better coverage. But I've already seen > that that misses things, too, there's more work to be done. I picked prepare_to_wait() just because I was hacking up something quick and thought that was "close enough" ;-) -- Steve