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=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 2B8DECA9EA0 for ; Fri, 18 Oct 2019 15:21:20 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id E5B74222C3 for ; Fri, 18 Oct 2019 15:21:19 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="BqMMQiiW" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E5B74222C3 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=33NSkEtgNvHyoNMPU5h/Tz0rtzhgbDlq5MCVsNRM0gQ=; b=BqMMQiiWdvoMXb rqeGZrxWMocaZ+HmRa5Jw8Z+FQrKyKO7KnxJKeWHZtyDQ8jn6Mlh0DQiMxy6s+pmaD3v8F6yA5QkR GWIhI9KdCTuugbpme9bAAkM/WQO4NiGkWezO+xYTYpolQLnooRq+DLfyng+ODFqvG/5c3FT6hr1Fg z882xUgn1iaQNvfSr2zOaAO88dk3BKyQP2MidiiJLz3XW7Wy1M+Szlk4CwS/IdU72fEmaGojBLn9R mDVXX7CLPkWPfkE/GSIzxIgEHwDA/A+WgTEgj3vVQ/9R5zvPbEhXlR8mdld5V0IE/aPzI0AjI0Txs tdQ6EO9ojCZvHzyn07Lg==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1iLU47-0007eq-8L; Fri, 18 Oct 2019 15:21:19 +0000 Received: from [217.140.110.172] (helo=foss.arm.com) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1iLU43-0007cz-HB for linux-arm-kernel@lists.infradead.org; Fri, 18 Oct 2019 15:21:17 +0000 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 CDC3AC8F; Fri, 18 Oct 2019 08:20:59 -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 0B4DA3F718; Fri, 18 Oct 2019 08:20:57 -0700 (PDT) Date: Fri, 18 Oct 2019 16:20:52 +0100 From: Sudeep Holla To: Yunfeng Ye Subject: Re: [PATCH v4] arm64: psci: Reduce the waiting time for cpu_psci_cpu_kill() Message-ID: <20191018152052.GA10312@bogus> References: <04ab51e4-bc08-8250-4e70-4c87c58c8ad0@huawei.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <04ab51e4-bc08-8250-4e70-4c87c58c8ad0@huawei.com> User-Agent: Mutt/1.9.4 (2018-02-28) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20191018_082115_643908_C4D0D3C2 X-CRM114-Status: GOOD ( 22.07 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: kstewart@linuxfoundation.org, mark.rutland@arm.com, lorenzo.pieralisi@arm.com, hushiyuan@huawei.com, catalin.marinas@arm.com, linux-kernel@vger.kernel.org, linfeilong@huawei.com, David.Laight@ACULAB.COM, gregkh@linuxfoundation.org, tglx@linutronix.de, wuyun.wu@huawei.com, will@kernel.org, linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Fri, Oct 18, 2019 at 08:46:37PM +0800, Yunfeng Ye wrote: > In case like suspend-to-disk and uspend-to-ram, a large number of CPU s/case/cases/ s/uspend-to-ram/suspend-to-ram/ > cores need to be 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, there is no need to wait 10ms in cpu_psci_cpu_kill(). So > change the wait interval from 10 ms to max 1 ms and use usleep_range() > instead of msleep() for more accurate timer. > > In addition, reducing the time interval will increase the messages > output, so remove the "Retry ..." message, instead, put the number of > waiting times to the sucessful message. > > Signed-off-by: Yunfeng Ye > --- > v3 -> v4: > - using time_before(jiffies, timeout) to check > - update the comment as review suggest > > 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 | 14 ++++++++------ > 1 file changed, 8 insertions(+), 6 deletions(-) > > diff --git a/arch/arm64/kernel/psci.c b/arch/arm64/kernel/psci.c > index c9f72b2665f1..77965c3ba477 100644 > --- a/arch/arm64/kernel/psci.c > +++ b/arch/arm64/kernel/psci.c > @@ -81,7 +81,8 @@ static void cpu_psci_cpu_die(unsigned int cpu) > > static int cpu_psci_cpu_kill(unsigned int cpu) > { > - int err, i; > + int err, i = 0; > + unsigned long timeout; > > if (!psci_ops.affinity_info) > return 0; > @@ -91,16 +92,17 @@ 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++) { > + timeout = jiffies + msecs_to_jiffies(100); > + do { > + 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 (polled %d times)\n", cpu, i); We can even drop loop counter completely, track time and log that instead of loop counter that doesn't give any indication without looking into the code. start = jiffies, end = start + msecs_to_jiffies(100); do { .... pr_info("CPU%d killed (polled %u ms)\n", cpu, jiffies_to_msecs(jiffies - start)); .... } while (time_before(jiffies, end)); Just my preference. Looks good otherwise. -- Regards, Sudeep _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel