From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752855AbdJSNXH (ORCPT ); Thu, 19 Oct 2017 09:23:07 -0400 Received: from 20pmail.ess.barracuda.com ([64.235.150.246]:43905 "EHLO 20pmail.ess.barracuda.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751793AbdJSNXE (ORCPT ); Thu, 19 Oct 2017 09:23:04 -0400 Subject: Re: [PATCH 1/3] clockevents: Retry programming min delta up to 10 times To: Thomas Gleixner CC: Daniel Lezcano , James Hogan , , James Hogan , Martin Schwidefsky , References: <1508414135-29123-1-git-send-email-matt.redfearn@mips.com> From: Matt Redfearn Message-ID: <5b782526-b130-77f2-6d9a-15839e12e065@mips.com> Date: Thu, 19 Oct 2017 14:21:23 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.3.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US X-Originating-IP: [10.150.130.83] X-BESS-ID: 1508419365-637140-11545-577074-8 X-BESS-VER: 2017.12-r1710102214 X-BESS-Apparent-Source-IP: 12.201.5.28 X-BESS-Outbound-Spam-Score: 0.00 X-BESS-Outbound-Spam-Report: Code version 3.2, rules version 3.2.2.186116 Rule breakdown below pts rule name description ---- ---------------------- -------------------------------- 0.00 BSF_BESS_OUTBOUND META: BESS Outbound X-BESS-Outbound-Spam-Status: SCORE=0.00 using account:ESS59374 scores of KILL_LEVEL=7.0 tests=BSF_BESS_OUTBOUND X-BESS-BRTS-Status: 1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 19/10/17 13:43, Thomas Gleixner wrote: > On Thu, 19 Oct 2017, Matt Redfearn wrote: >> unsigned long long clc; >> int64_t delta; >> + int i; >> >> - delta = dev->min_delta_ns; >> - dev->next_event = ktime_add_ns(ktime_get(), delta); >> + for (i = 0;;) { > Bah. What's wrong with > > for (i = 0; i < 10; i++) { > > .... > if (!(dev->set_next_event((unsigned long) clc, dev)) > return 0; > } > return -ETIME; > > Hmm? Sure, can make it like that. >> + delta = dev->min_delta_ns; >> + dev->next_event = ktime_add_ns(ktime_get(), delta); >> >> - if (clockevent_state_shutdown(dev)) >> - return 0; >> + if (clockevent_state_shutdown(dev)) >> + return 0; >> >> - dev->retries++; >> - clc = ((unsigned long long) delta * dev->mult) >> dev->shift; >> - return dev->set_next_event((unsigned long) clc, dev); >> + dev->retries++; >> + clc = ((unsigned long long) delta * dev->mult) >> dev->shift; > I'd rather make that: > > delta = 0; > for (i = 0; i < 10; i++) { > delta += dev->min_delta_ns; > dev->next_event = ktime_add_ns(ktime_get(), delta); > clc = ..... > ..... > > That makes it more likely to succeed fast. Hmm? That will set the target time to increasing multiples of min_delta_ns in the future, right? Sure, it should make it succeed faster - I'll make it like that. Are you OK with the arbitrarily chosen 10 retries? Thanks, Matt > > Thanks, > > tglx