Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753047AbaGHCvU (ORCPT ); Mon, 7 Jul 2014 22:51:20 -0400 Received: from szxga02-in.huawei.com ([119.145.14.65]:36348 "EHLO szxga02-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751690AbaGHCvS (ORCPT ); Mon, 7 Jul 2014 22:51:18 -0400 Message-ID: <53BB5C96.2040203@huawei.com> Date: Tue, 8 Jul 2014 10:51:02 +0800 From: "xiaofeng.yan" User-Agent: Mozilla/5.0 (Windows NT 6.1; rv:17.0) Gecko/20130801 Thunderbird/17.0.8 MIME-Version: 1.0 To: Li Zefan CC: Peter Zijlstra , , , , Juri Lelli Subject: Re: [PATCH] sched/rt: overrun could happen in start_hrtick_dl References: <1404475341-22536-1-git-send-email-xiaofeng.yan@huawei.com> <20140707084150.GC19379@twins.programming.kicks-ass.net> <53BB4510.5090704@huawei.com> <53BB5A13.1070305@huawei.com> In-Reply-To: <53BB5A13.1070305@huawei.com> Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [10.111.68.133] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2014/7/8 10:40, Li Zefan wrote: > On 2014/7/8 9:10, xiaofeng.yan wrote: >> On 2014/7/7 16:41, Peter Zijlstra wrote: >>> On Fri, Jul 04, 2014 at 12:02:21PM +0000, xiaofeng.yan wrote: >>>> It could be wrong for the precision of runtime and deadline >>>> when the precision is within microsecond level. For example: >>>> Task runtime deadline period >>>> P1 200us 500us 500us >>>> >>>> This case need enbale HRTICK feature by the next command >>>> PC#echo "HRTICK" > /sys/kernel/debug/sched_features >>>> PC#./schedtool -E -t 200000:500000 -e ./test& >>>> PC#trace-cmd record -e sched_switch >>> Are you actually using HRTICK ? >> yes, If HRTICK is close , then all of runtime and deadline will be wrong. > I think what peter meant is, do you use HRTICK in products or > just use it for testing/experiment? > Thanks for your timely comments. In fact, We use HRTICK feature in product. We need microsecond level precision. Thanks Yan > . > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/