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=-8.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=ham 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 133CFCA9EA0 for ; Fri, 18 Oct 2019 12:03:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E105721D7C for ; Fri, 18 Oct 2019 12:03:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2407830AbfJRMDn (ORCPT ); Fri, 18 Oct 2019 08:03:43 -0400 Received: from szxga04-in.huawei.com ([45.249.212.190]:4689 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S2392487AbfJRMDn (ORCPT ); Fri, 18 Oct 2019 08:03:43 -0400 Received: from DGGEMS407-HUB.china.huawei.com (unknown [172.30.72.59]) by Forcepoint Email with ESMTP id 48475E0CF41259E163D3; Fri, 18 Oct 2019 20:03:40 +0800 (CST) Received: from [127.0.0.1] (10.177.251.225) by DGGEMS407-HUB.china.huawei.com (10.3.19.207) with Microsoft SMTP Server id 14.3.439.0; Fri, 18 Oct 2019 20:03:31 +0800 Subject: Re: [PATCH V3] arm64: psci: Reduce waiting time for cpu_psci_cpu_kill() To: Sudeep Holla CC: , , , , , , , , , , "hushiyuan@huawei.com" , , "linfeilong@huawei.com" References: <433980c7-f246-f741-f00c-fce103a60af7@huawei.com> <20191018114529.GA15116@bogus> From: Yunfeng Ye Message-ID: <0baccab6-9804-7b59-0ad6-765af7980714@huawei.com> Date: Fri, 18 Oct 2019 20:03:28 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: <20191018114529.GA15116@bogus> Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.177.251.225] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2019/10/18 19:45, Sudeep Holla wrote: > 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..." > ok, thanks. >> 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/ > ok, thanks. >> 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/ > ok, thanks. >> In addition, reduce the time interval will increase the messages output, > > s/reduce/reducing/ > ok, thanks. >> 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 ? > ok, if using (time_before(jiffies, timeout)), the output message change to print waiting xxx jiffies ? or still print the number of loops? > -- > Regards, > Sudeep > > . >