From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.1 (2015-04-28) on archive.lwn.net X-Spam-Level: X-Spam-Status: No, score=-6.2 required=5.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=unavailable autolearn_force=no version=3.4.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by archive.lwn.net (Postfix) with ESMTP id 7824D7D08A for ; Tue, 11 Dec 2018 07:28:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726094AbeLKH2R (ORCPT ); Tue, 11 Dec 2018 02:28:17 -0500 Received: from cmta17.telus.net ([209.171.16.90]:59834 "EHLO cmta17.telus.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726085AbeLKH2R (ORCPT ); Tue, 11 Dec 2018 02:28:17 -0500 Received: from dougxps ([173.180.45.4]) by cmsmtp with SMTP id WcSfgdL0SP96wWcSggwQ7d; Tue, 11 Dec 2018 00:28:14 -0700 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=telus.net; s=neo; t=1544513294; bh=CVpunYFypL/dXiyjG9R9gzj4K4lgYzkFiiwy2UAzYyE=; h=From:To:Cc:References:In-Reply-To:Subject:Date; b=5F/9RpJoXyVUdxml5XvA/fodUx92Tj9HZsTBRZjw0yhiTeV+/4hcfyxHnhJn3WWm5 T2f+q856LoEekCxVvJ5raAnZ8LFrcWBVgXlJdc/jg6yP0UeayLLEqIrI/TMoX2Hkhf I5MG6lOJO04EmlFG88zxDZYw6WC/uJ7GT1VLCD2FSOj56Y/vLesKhXOVTzOgfVF9bt pL1bvs+o4b0cCipEM/qaMEmkSEDAdx7CXF9WJIaQ+nBccmX2d1+gGy3tKzmx5fwOBm NWqnItXKTqR4EOpErlugmgKgBLjwa0fRxBBCiSIkiUX0bO6NvMIOpJ82Zwn6IWAK8y gtJ/VqCUIUJZQ== X-Authority-Analysis: v=2.3 cv=G5vN7Os5 c=1 sm=1 tr=0 a=zJWegnE7BH9C0Gl4FFgQyA==:117 a=zJWegnE7BH9C0Gl4FFgQyA==:17 a=Pyq9K9CWowscuQLKlpiwfMBGOR0=:19 a=kj9zAlcOel0A:10 a=JfrnYn6hAAAA:8 a=j_xubRRabc_gLPjOC1IA:9 a=CjuIK1q_8ugA:10 a=1CNFftbPRP8L7MoqJWF3:22 From: "Doug Smythies" To: "'Peter Zijlstra'" , "'Rafael J. Wysocki'" Cc: "'Rafael J. Wysocki'" , "'Linux PM'" , "'Linux Kernel Mailing List'" , "'open list:DOCUMENTATION'" , "'Daniel Lezcano'" , "'Giovanni Gherdovich'" , "'Lorenzo Pieralisi'" , "Doug Smythies" References: <3514439.dzOWKx1Cjx@aspire.rjw.lan> <20181210122104.GL5289@hirez.programming.kicks-ass.net> WUOsgxly2wifMWUOxgv0We In-Reply-To: WUOsgxly2wifMWUOxgv0We Subject: RE: [PATCH v2] cpuidle: Add 'above' and 'below' idle state metrics Date: Mon, 10 Dec 2018 23:28:07 -0800 Message-ID: <003401d49123$13627710$3a276530$@net> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit X-Mailer: Microsoft Office Outlook 12.0 Thread-Index: AdSQ2u+9QZn0bxubQISdP83AHOeGqAARHUkw Content-Language: en-ca X-CMAE-Envelope: MS4wfC33gNEF43A6YSw0pX/n+IeerjIUSXbDcDusVBnW+qrmWiQiKxZtEuoW9qt38DIJZpL6Fe7dfay05A3bOPn6rB+wua9/yslg8OuvigUbli+qBWf0DZyt l6UjzQjYaBxSPRaTRERa6Y7Dn4z11vb3P9zxb4GtTvDt/hEozTnWT19YgJ9lfrOecP7UfcYPHjFePlrHDq95gE4icUv9hEHv1e4BQXWiaKF+g5qGhy0Gyw/B DidzH4wMfzWOkIclJg+F/UVRDHK1LMXmC0Ifq07u64Wtipwz8545+jXLO2zzGbeGbj5vQqI4e5PdcXnAxIq4GVUN6WWmfnWllZdQjkgLomAlgpC1+QxOHy7X HlxVxPMXoYh3D0lHyPSsfMnv356Ltz47Y+ALgW5jGwaM7PYjvEK/Prs1Blghp4dGNx78dQwKNPmPS0G+miKvIeJY6INWByVJfpjCstvpXnU35s72g3Z0ima4 HKVlPJOAEefnUdVV Sender: linux-doc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org On 2018.12.10 02:52 Peter Zijlstra wrote: >On Mon, Dec 10, 2018 at 10:36:40PM +0100, Rafael J. Wysocki wrote: >> On Mon, Dec 10, 2018 at 1:21 PM Peter Zijlstra wrote: >>> Would not a tracepoint be better?; then there is no overhead in the >>> normal case where nobody gives a crap about these here numbers. >> >> There is an existing tracepoint that in principle could be used to >> produce this information, but it is such a major PITA in practice that >> nobody does that. Guess why. :-) > > Sounds like you need to ship a convenient script or something :-) For the histogram plots of idle durations that I sometimes provide, trace is used. It is more work to do it the trace way. Very often, when the rate of idle state entries/ exits is high, turning on trace influences the system under test significantly. Also, even if I allocate the majority of my memory to the trace buffer (i.e. 15 of my 16 gigabytes), I can only acquire a few minutes of trace data before filling the buffer. Some of my tests run for hours, and these new counters provide a way to acquire potentially useful (I don't have enough experience with them yet to know how useful) information, while having no influence on the system under test because I only take samples once per minute, or sometimes 4 times per minute. >> Also, the "usage" and "time" counters are there in sysfs, so why not these two? I agree, how are these two counters any different? In about a week or so, I'll have some test data comparing 4.20-rc5 with teov6 teov7 along with the idle data (graphs) that I usually provide and also these new counters. ... Doug