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=-2.0 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 C045BC3A589 for ; Tue, 20 Aug 2019 09:39:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8887B20673 for ; Tue, 20 Aug 2019 09:39:02 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="hgKdt0P1" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729529AbfHTJjB (ORCPT ); Tue, 20 Aug 2019 05:39:01 -0400 Received: from merlin.infradead.org ([205.233.59.134]:34840 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728414AbfHTJjB (ORCPT ); Tue, 20 Aug 2019 05:39:01 -0400 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:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=aP7YVXFpDNQcxH+rVOzu1yptj8ZkIgU2FgwQQZibl+g=; b=hgKdt0P1DD3mZ+BKU2LYDAoWF 786hK7vhHqfPFXT13TPQoAUO0gj6XJ5HKdH3ATpIQuCrBtTQAlLK3BB+Mwqa6l+0VASGsSWfqlPWi uAxGMo3t2sNV9tVYrrVXM94gadC6ROFX9Uvevyr8ViFv8L9i9lPtKJtp8ACTapJC6JQyDtXBKPtIh +lENen5l42kkNVFSmXunJRpJ3UHwxw2bV7Ojo6XEYHdwnM7M+nYGZRE800V44QfV1yFwT4MGukJQB Wx4NlUTTjq7u0D9ytpUospPZIp4StFs0kQhIlcWTyQT/WUwEj9RRMLWWIyy615d/hV8u7gcW69kJ4 qzRiaUu4g==; 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 (Red Hat Linux)) id 1i00b1-0005wW-9B; Tue, 20 Aug 2019 09:38:35 +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 9CE3B307603; Tue, 20 Aug 2019 11:37:56 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id B047020CE7741; Tue, 20 Aug 2019 11:38:27 +0200 (CEST) Date: Tue, 20 Aug 2019 11:38:27 +0200 From: Peter Zijlstra To: longli@linuxonhyperv.com Cc: Ingo Molnar , Keith Busch , Jens Axboe , Christoph Hellwig , Sagi Grimberg , linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org, Long Li Subject: Re: [PATCH 1/3] sched: define a function to report the number of context switches on a CPU Message-ID: <20190820093827.GF2332@hirez.programming.kicks-ass.net> References: <1566281669-48212-1-git-send-email-longli@linuxonhyperv.com> <1566281669-48212-2-git-send-email-longli@linuxonhyperv.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1566281669-48212-2-git-send-email-longli@linuxonhyperv.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Aug 19, 2019 at 11:14:27PM -0700, longli@linuxonhyperv.com wrote: > From: Long Li > > The number of context switches on a CPU is useful to determine how busy this > CPU is on processing IRQs. Export this information so it can be used by device > drivers. Please do explain that; because I'm not seeing how number of switches relates to processing IRQs _at_all_!