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 C033CEB64DA for ; Wed, 19 Jul 2023 13:18:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230076AbjGSNSB (ORCPT ); Wed, 19 Jul 2023 09:18:01 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44702 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231145AbjGSNR6 (ORCPT ); Wed, 19 Jul 2023 09:17:58 -0400 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 57BAC172A; Wed, 19 Jul 2023 06:17:51 -0700 (PDT) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 3486B2F4; Wed, 19 Jul 2023 06:18:34 -0700 (PDT) Received: from [10.57.31.26] (unknown [10.57.31.26]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id D3C2A3F6C4; Wed, 19 Jul 2023 06:17:47 -0700 (PDT) Message-ID: <42118979-5f86-75df-72a5-e5fc8592eb82@arm.com> Date: Wed, 19 Jul 2023 14:18:17 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.11.0 Subject: Re: [RESEND][PATCH v2 1/3] sched/tp: Add new tracepoint to track uclamp set from user-space Content-Language: en-US To: Peter Zijlstra Cc: linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, rafael@kernel.org, linux-pm@vger.kernel.org, rostedt@goodmis.org, mhiramat@kernel.org, mingo@redhat.com, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, bsegall@google.com, mgorman@suse.de, bristot@redhat.com, vschneid@redhat.com, delyank@fb.com, qyousef@google.com, Qais Yousef References: <20230522145702.2419654-1-lukasz.luba@arm.com> <20230522145702.2419654-2-lukasz.luba@arm.com> <20230531182629.nztie5rwhjl53v3d@airbuntu> <20230706111443.GH2833176@hirez.programming.kicks-ass.net> From: Lukasz Luba In-Reply-To: <20230706111443.GH2833176@hirez.programming.kicks-ass.net> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-trace-kernel@vger.kernel.org On 7/6/23 12:14, Peter Zijlstra wrote: > On Wed, May 31, 2023 at 07:26:29PM +0100, Qais Yousef wrote: >> On 05/22/23 15:57, Lukasz Luba wrote: >>> The user-space can set uclamp value for a given task. It impacts task >>> placement decisions made by the scheduler. This is very useful information >>> and helps to understand the system behavior or track improvements in >>> middleware and applications which start using uclamp mechanisms and report >>> better performance in tests. >> >> Do you mind adding a generic one instead please? And explain why we can't just >> attach to the syscall via kprobes? I think you want to bypass the permission >> checks, so maybe a generic tracepoint after that might be justifiable? >> Then anyone can use it to track how userspace has changed any attributes for >> a task, not just uclamp. > > Yeah, so I'm leaning towards the same, if you want to put a tracepoint > in __sched_setscheduler(), just trace the whole attr and leave it at > that: > > trace_update_sched_attr_tp(p, attr); > > or somesuch. > OK, fair enough, I'll do that. Thanks Peter! (I'm sorry for the delay, I was on vacation) Lukasz