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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable 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 F230FCA9EA1 for ; Fri, 18 Oct 2019 11:46:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D195D20700 for ; Fri, 18 Oct 2019 11:46:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2409916AbfJRLqG (ORCPT ); Fri, 18 Oct 2019 07:46:06 -0400 Received: from [217.140.110.172] ([217.140.110.172]:36394 "EHLO foss.arm.com" rhost-flags-FAIL-FAIL-OK-OK) by vger.kernel.org with ESMTP id S2389864AbfJRLqG (ORCPT ); Fri, 18 Oct 2019 07:46:06 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 4D43DCA3; Fri, 18 Oct 2019 04:45:45 -0700 (PDT) Received: from bogus (e107155-lin.cambridge.arm.com [10.1.196.42]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 7F1EE3F6C4; Fri, 18 Oct 2019 04:45:43 -0700 (PDT) Date: Fri, 18 Oct 2019 12:45:29 +0100 From: Sudeep Holla To: Yunfeng Ye Cc: catalin.marinas@arm.com, will@kernel.org, kstewart@linuxfoundation.org, gregkh@linuxfoundation.org, lorenzo.pieralisi@arm.com, tglx@linutronix.de, David.Laight@ACULAB.COM, ard.biesheuvel@linaro.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, "hushiyuan@huawei.com" , wuyun.wu@huawei.com, "linfeilong@huawei.com" Subject: Re: [PATCH V3] arm64: psci: Reduce waiting time for cpu_psci_cpu_kill() Message-ID: <20191018114529.GA15116@bogus> References: <433980c7-f246-f741-f00c-fce103a60af7@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <433980c7-f246-f741-f00c-fce103a60af7@huawei.com> 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 Fri, Oct 18, 2019 at 07:24:14PM +0800, Yunfeng Ye wrote: > In a case like suspend-to-disk, a large number of CPU cores need to be Add suspend-to-ram also to list, i.e. "In case like suspend-to-disk and suspend-to-ram, a large number..." > shut down. At present, the CPU hotplug operation is serialised, and the > CPU cores can only be shut down one by one. In this process, if PSCI > affinity_info() does not return LEVEL_OFF quickly, cpu_psci_cpu_kill() > needs to wait for 10ms. If hundreds of CPU cores need to be shut down, > it will take a long time. > > Normally, it is no need to wait 10ms in cpu_psci_cpu_kill(). So change s/it is/there is/ > the wait interval from 10 ms to max 1 ms and use usleep_range() instead > of msleep() for more accurate schedule. > s/for more accurate schedule/for more accurate timer/ > In addition, reduce the time interval will increase the messages output, s/reduce/reducing/ > so remove the "Retry ..." message, instead, put the number of waiting > times to the sucessful message. > > Signed-off-by: Yunfeng Ye > --- > v2 -> v3: > - update the comment > - remove the busy-wait logic, modify the loop logic and output message > > v1 -> v2: > - use usleep_range() instead of udelay() after waiting for a while > > arch/arm64/kernel/psci.c | 7 +++---- > 1 file changed, 3 insertions(+), 4 deletions(-) > > diff --git a/arch/arm64/kernel/psci.c b/arch/arm64/kernel/psci.c > index c9f72b2665f1..00b8c0825a08 100644 > --- a/arch/arm64/kernel/psci.c > +++ b/arch/arm64/kernel/psci.c > @@ -91,15 +91,14 @@ static int cpu_psci_cpu_kill(unsigned int cpu) > * while it is dying. So, try again a few times. > */ > > - for (i = 0; i < 10; i++) { > + for (i = 0; i < 100; i++) { > err = psci_ops.affinity_info(cpu_logical_map(cpu), 0); > if (err == PSCI_0_2_AFFINITY_LEVEL_OFF) { > - pr_info("CPU%d killed.\n", cpu); > + pr_info("CPU%d killed by waiting %d loops.\n", cpu, i); > return 0; > } > > - msleep(10); > - pr_info("Retrying again to check for CPU kill\n"); > + usleep_range(100, 1000); Since usleep_range can return anytime between 100us to 1ms, does it make sense to check for (time_before(jiffies, timeout)) you had in v2 ? -- Regards, Sudeep