From patchwork Wed Sep 11 08:50:08 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yunfeng Ye X-Patchwork-Id: 11140663 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id D2963112B for ; Wed, 11 Sep 2019 08:50:57 +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 A79BF21A4C for ; Wed, 11 Sep 2019 08:50:57 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="G87UNSMa" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A79BF21A4C Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=huawei.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.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:MIME-Version:Date:Message-ID:Subject: From:To:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To:References: List-Owner; bh=HANcoZiWN09bIfEhCEFbVuIuJtPIVOdhrphEnhIRIbM=; b=G87UNSMaSXlHYW 9Rx9fqfEcmCDekF/ASCqx8unawzzHd6qKm/+lanRxI0RNyaeSbipyd1hh1uNJ9f94dyRMYDOUJIV5 ObH8G7byDET72s4ppjMv+JfXQ6MLhZxKDPh1C6rzmhKXnYpap7JQW6oVcxu7KVtEtQOjxKrlCscvN XIlGRsZ/dbioKWzSont+6p/xRsv/vo1rpVKMgWSPDgjo8qHnFBEtgH3/wirw9s/XdBRO/pzTpbzox EraAqEYEK+P9Z73Fjdx3IFp0tTHdJWCVvNqaFXuFRyVrH/vpqJ00vubTfiyBmpLMwtFUNtTxEH4qI jAK99EL+eHZ9Al92b9Ow==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92 #3 (Red Hat Linux)) id 1i7yKw-0007zB-Of; Wed, 11 Sep 2019 08:50:50 +0000 Received: from szxga04-in.huawei.com ([45.249.212.190] helo=huawei.com) by bombadil.infradead.org with esmtps (Exim 4.92 #3 (Red Hat Linux)) id 1i7yKt-0007yX-TA for linux-arm-kernel@lists.infradead.org; Wed, 11 Sep 2019 08:50:49 +0000 Received: from DGGEMS403-HUB.china.huawei.com (unknown [172.30.72.58]) by Forcepoint Email with ESMTP id 1641D4EFB943E5F659AA; Wed, 11 Sep 2019 16:50:39 +0800 (CST) Received: from [127.0.0.1] (10.177.251.225) by DGGEMS403-HUB.china.huawei.com (10.3.19.203) with Microsoft SMTP Server id 14.3.439.0; Wed, 11 Sep 2019 16:50:29 +0800 To: , From: Yunfeng Ye Subject: [PATCH] arm64: psci: Use udelay() instead of msleep() to reduce waiting time Message-ID: Date: Wed, 11 Sep 2019 16:50:08 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 Content-Language: en-US X-Originating-IP: [10.177.251.225] X-CFilter-Loop: Reflected X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190911_015048_112155_175FF4CA X-CRM114-Status: GOOD ( 12.88 ) X-Spam-Score: -2.3 (--) X-Spam-Report: SpamAssassin version 3.4.2 on bombadil.infradead.org summary: Content analysis details: (-2.3 points) pts rule name description ---- ---------------------- -------------------------------------------------- -2.3 RCVD_IN_DNSWL_MED RBL: Sender listed at https://www.dnswl.org/, medium trust [45.249.212.190 listed in list.dnswl.org] -0.0 SPF_PASS SPF: sender matches SPF record -0.0 SPF_HELO_PASS SPF: HELO matches SPF record 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, ard.biesheuvel@linaro.org, gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, tglx@linutronix.de, wuyun.wu@huawei.com, linux-arm-kernel@lists.infradead.org Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org We want to reduce the time of cpu_down() for saving power, found that cpu_psci_cpu_kill() cost 10ms after psci_ops.affinity_info() fail. Normally the time cpu dead is very short, it is no need to wait 10ms. so use udelay 10us to instead msleep 10ms in every waiting loop, and add cond_resched() to give a chance to run a higher-priority process. Signed-off-by: Yunfeng Ye --- arch/arm64/kernel/psci.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/arch/arm64/kernel/psci.c b/arch/arm64/kernel/psci.c index 85ee7d0..9e9d8a6 100644 --- a/arch/arm64/kernel/psci.c +++ b/arch/arm64/kernel/psci.c @@ -86,15 +86,15 @@ 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 < 10000; 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); return 0; } - msleep(10); - pr_info("Retrying again to check for CPU kill\n"); + cond_resched(); + udelay(10); } pr_warn("CPU%d may not have shut down cleanly (AFFINITY_INFO reports %d)\n",