Received: by 10.213.65.68 with SMTP id h4csp485016imn; Wed, 28 Mar 2018 07:18:35 -0700 (PDT) X-Google-Smtp-Source: AIpwx49BBF7m4jJ8zC1hHXST2wgZDF2GIOwJ0/sqQdNP4/XiO0hCNTUGqhzhQueyLoV3P/0lSutT X-Received: by 10.101.86.70 with SMTP id m6mr2756286pgs.349.1522246715552; Wed, 28 Mar 2018 07:18:35 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1522246715; cv=none; d=google.com; s=arc-20160816; b=T1xMHGCr7H6YZ8E0jx2glmIHl9lm5fj0cbWqKKyaKiSDj4XSpXM3T4/tSbxg98n8dY IcD8FlahT3IIk4TGbjze55bdVTtfGTRqH7fi0rKjbSye7jlkmBJx+dX7xXYKp4jUKlCL hwcaz5csQMUEtA+GcSEQwPP7LoJmJ97y0h0A2smXJTrmieU0qNmtAyD41BPWDttkk3kW l3bg+f93Bjusvl369pmJX7YD0vYrS52xk3MU8wNd0JG86o1Wef6RKb+vmi7sz5uQi7A8 YhEwPboPBWTHlLmIdDGHcBtILva/XnZ77ClBDicswNZWR3p6dvOnxx9B2v0XL4TU0zHs UVgw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:user-agent:in-reply-to :content-transfer-encoding:content-disposition:mime-version :references:message-id:subject:cc:to:from:date :arc-authentication-results; bh=TCrr60YsQw4WtgKal1FyJOvVg3z2ifJCogCKqpdrCNM=; b=pyDV29VI+YZblvsO9vBeC5RETENDfwJH+9/HUqVFCpX9VP/LOvjjZxBmF/E+Jw230p FvNsk3M37fygyFMVLkEp5CsxuA+YXlVX8uoQGHQq9qrGYrLP+enUPvd1r8GfhoAiupRY Ge7QjNp+L+eMAdVRS+9/R5owf9c6E1rzuor/2ob5nUpoguRKrCnRtEGmRc6PbglqX2pF cxteFyg/+sqPNzHLXx7qxCRLEJfRzCzX7cggdcWYjFiHqTEzpYqfN3xY7bq+R84BMpnu az/Mvoc/VMZXQT40ipNZhDZJXttF37Hy8pgY5NBokyjhOsuJrl/hae46VtbPz73A+8fl Q1Rw== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id l8si2533050pgr.187.2018.03.28.07.18.20; Wed, 28 Mar 2018 07:18:35 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753440AbeC1OQr (ORCPT + 99 others); Wed, 28 Mar 2018 10:16:47 -0400 Received: from mail.bootlin.com ([62.4.15.54]:35325 "EHLO mail.bootlin.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753406AbeC1OQq (ORCPT ); Wed, 28 Mar 2018 10:16:46 -0400 Received: by mail.bootlin.com (Postfix, from userid 110) id 96AB42070F; Wed, 28 Mar 2018 16:16:44 +0200 (CEST) X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on mail.bootlin.com X-Spam-Level: X-Spam-Status: No, score=-1.0 required=5.0 tests=ALL_TRUSTED,SHORTCIRCUIT, URIBL_BLOCKED shortcircuit=ham autolearn=disabled version=3.4.0 Received: from localhost (242.171.71.37.rev.sfr.net [37.71.171.242]) by mail.bootlin.com (Postfix) with ESMTPSA id 42C882037A; Wed, 28 Mar 2018 16:16:44 +0200 (CEST) Date: Wed, 28 Mar 2018 16:16:45 +0200 From: Alexandre Belloni To: Daniel Lezcano Cc: Alexander Dahl , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Boris Brezillon , Thomas Gleixner Subject: Re: [PATCH v3 0/6] clocksource: rework Atmel TCB timer driver Message-ID: <20180328141645.GF13942@piout.net> References: <20180223171558.7037-1-alexandre.belloni@bootlin.com> <9761072.pX2B0LJlSJ@ada> <989df8a3-462a-c645-87f1-9f956e1b22c9@linaro.org> <4073350.0MmxRoANOi@ada> <6d43177a-bbea-6a01-5fa5-1c7891e18412@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <6d43177a-bbea-6a01-5fa5-1c7891e18412@linaro.org> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 28/03/2018 at 15:03:11 +0200, Daniel Lezcano wrote: > On 28/03/2018 12:29, Alexander Dahl wrote: > > Hello Daniel, > > > > Am Dienstag, 27. M?rz 2018, 13:30:22 CEST schrieb Daniel Lezcano: > >> Can you can give a rough amount for the irq rate on the timer ? > > > > I used itop [1] now to get a rough estimate. First with kernel v4.14.29-rt25 > > (fully preempt RT): > > > > INT NAME RATE MAX > > 19 [ vel tc_clkevt] 397 Ints/s (max: 432) > > 26 [ vel eth0] 4 Ints/s (max: 38) > > > > Next test with kernel v4.15.13 gives (slightly slower, but non-RT): > > > > INT NAME RATE MAX > > 19 [ vel tc_clkevt] 248 Ints/s (max: 273) > > 26 [ vel eth0] 4 Ints/s (max: 11) > > > > With kernel v4.16-rc7 plus this patch series and tcb as clocksource: > > > > INT NAME RATE MAX > > 17 [vel timer@fffa] 2164 Ints/s (max: 2183) > > 26 [ vel eth0] 5 Ints/s (max: 10) > > > > Is this the information you wanted? If not, could you point me on how to get > > the requested irq rate? > > It is perfect. Thanks! > > It confirms what I was worried about: the clocksource wraps up too > quickly thus raising an interrupt every 400us. That is why I asked > Alexande about a prescalar register. > The code should behave exactly the same between the previous and the new driver. The interrupt is not coming from the clocksource but from the clockevent and it is already on the slowest clock, the 32kHz one. -- Alexandre Belloni, Bootlin (formerly Free Electrons) Embedded Linux and Kernel engineering https://bootlin.com