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=-3.9 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS 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 4B6E6C4346E for ; Thu, 24 Sep 2020 08:34:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DC26923787 for ; Thu, 24 Sep 2020 08:34:30 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="mfl5OeBP" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727274AbgIXIe3 (ORCPT ); Thu, 24 Sep 2020 04:34:29 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59366 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727046AbgIXIe2 (ORCPT ); Thu, 24 Sep 2020 04:34:28 -0400 Received: from merlin.infradead.org (merlin.infradead.org [IPv6:2001:8b0:10b:1231::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BCC26C0613CE for ; Thu, 24 Sep 2020 01:34:27 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=OUHUdYJD7r+VuVVENErfQFGZk/hWw89tE0SaaaDXEkg=; b=mfl5OeBPIblDvnWsP3HHx5Ez12 MaSGxgBXIxx0ipqkpyqu+85OmiAqAXD8CGI5aNqzdkbxlcImP5Eg9FbSmtxMfq2TfCcGo9R4bqWPy Eq0QT6gOEzkm1tRDXAAlFs5palDRIB3QmNQz100LlbCXotXaq3WAu5Yay+DbuAVQ9LCfvFIIo9z86 tE42jdwc6SlQmXPxbuqzLQpEel1CYsn9GP2Wfev1rsOFVOZX66VCRM3daOYrAoC6uqrZEcj9f3/wK ok/I73Kr8TIxibWuM8YSb64mwIqJqTsysCLyKCtZr6IiCH/AyhcCTrEU60xGEVFvyNNj2LDU0m4a0 PkYnttGQ==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1kLMhk-00053L-U2; Thu, 24 Sep 2020 08:34:17 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 26578300455; Thu, 24 Sep 2020 10:34:14 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id E103B2BC0B6AD; Thu, 24 Sep 2020 10:34:14 +0200 (CEST) Date: Thu, 24 Sep 2020 10:34:14 +0200 From: peterz@infradead.org To: Prasad Sodagudi Cc: rostedt@goodmis.org, tglx@linutronix.de, qais.yousef@arm.com, mingo@kernel.org, cai@lca.pw, tyhicks@canonical.com, arnd@arndb.de, rameezmustafa@codeaurora.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 0/2] measure latency of cpu hotplug path Message-ID: <20200924083414.GB1362448@hirez.programming.kicks-ass.net> References: <1600904266-102397-1-git-send-email-psodagud@codeaurora.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1600904266-102397-1-git-send-email-psodagud@codeaurora.org> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Sep 23, 2020 at 04:37:44PM -0700, Prasad Sodagudi wrote: > There are all changes related to cpu hotplug path and would like to seek > upstream review. These are all patches in Qualcomm downstream kernel > for a quite long time. First patch sets the rt prioity to hotplug > task and second patch adds cpuhp trace events. > > 1) cpu-hotplug: Always use real time scheduling when hotplugging a CPU > 2) cpu/hotplug: Add cpuhp_latency trace event Why? Hotplug is a known super slow path. If you care about hotplug latency you're doing it wrong.