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=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_2 autolearn=no 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 622FFC07E96 for ; Wed, 7 Jul 2021 00:50:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 487D061CAA for ; Wed, 7 Jul 2021 00:50:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230002AbhGGAxW (ORCPT ); Tue, 6 Jul 2021 20:53:22 -0400 Received: from mail.kernel.org ([198.145.29.99]:41666 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229834AbhGGAxW (ORCPT ); Tue, 6 Jul 2021 20:53:22 -0400 Received: from rorschach.local.home (cpe-66-24-58-225.stny.res.rr.com [66.24.58.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 0C81161CAA; Wed, 7 Jul 2021 00:50:41 +0000 (UTC) Date: Tue, 6 Jul 2021 20:50:39 -0400 From: Steven Rostedt To: Namhyung Kim Cc: LKML , Ingo Molnar , Andrew Morton , Tom Zanussi , Masami Hiramatsu , "Daniel Bristot de Oliveira Subject: [PATCH] tracing:" Subject: Re: [PATCH v2] tracing: Add linear buckets to histogram logic Message-ID: <20210706205039.64182493@rorschach.local.home> In-Reply-To: References: <20210706154315.3567166e@gandalf.local.home> 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: linux-kernel@vger.kernel.org On Tue, 6 Jul 2021 16:20:07 -0700 Namhyung Kim wrote: > > { bytes_req: ~ 1400-1499 } hitcount: 30 > > { bytes_req: ~ 2000-2099 } hitcount: 6 > > { bytes_req: ~ 4000-4099 } hitcount: 2168 > > { bytes_req: ~ 5000-5099 } hitcount: 6 > > For consistency with the log2 histogram, I'd like to see > > { bytes_req: ~ 100 } hitcount: 3149 > { bytes_req: ~ 200 } hitcount: 1468 > { bytes_req: ~ 300 } hitcount: 39 > ... > > Or, if you really care about the value range > > { bytes_req: 0 ~ 99 } hitcount: 3149 > { bytes_req: 100 ~ 199 } hitcount: 1468 > { bytes_req: 200 ~ 299 } hitcount: 39 (Let the bike-shedding begin! ;-) I actually dislike the log2 notation. For example, I just ran it with this: ># echo 'hist:keys=bytes_req.log2:sort=bytes_req' > events/kmem/kmalloc/trigger ># cat events/kmem/kmalloc/hist # event histogram # # trigger info: hist:keys=bytes_req.log2:vals=hitcount:sort=bytes_req.log2:size=2048 [active] # { bytes_req: ~ 2^5 } hitcount: 8 { bytes_req: ~ 2^6 } hitcount: 2 { bytes_req: ~ 2^7 } hitcount: 4 { bytes_req: ~ 2^8 } hitcount: 2 { bytes_req: ~ 2^9 } hitcount: 2 { bytes_req: ~ 2^10 } hitcount: 3 Totals: Hits: 21 Entries: 6 Dropped: 0 And I don't know if that first entry is: 2^4 - 2^5 or if it is 2^5 - 2^6. And to me '~' means "approximately", but I also took it as "not exactly". I used it as: { bytes_req: ~ 1400-1499 } hitcount: 30 To mean, it's "approximately somewhere between 1400 and 1499" so, I kept the "~". Now for your suggestions: > { bytes_req: ~ 100 } hitcount: 3149 > { bytes_req: ~ 200 } hitcount: 1468 > { bytes_req: ~ 300 } hitcount: 39 Suffers the same fate as I dislike in log2. Is " ~ 100" 0-100 or 100-200? > { bytes_req: 0 ~ 99 } hitcount: 3149 > { bytes_req: 100 ~ 199 } hitcount: 1468 > { bytes_req: 200 ~ 299 } hitcount: 39 I feel is farther from log2 than my version. Stating that "~" means approximation, what does "0 ~ 99" really mean? So far I prefer my original version. BTW, we are also working on a user space parser for this, thus the output format of all hist logic is going to be a user space API (if it hasn't already become one.) So we do need to get this correct for the long haul. -- Steve