From patchwork Fri Mar 25 03:08:55 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jisheng Zhang X-Patchwork-Id: 8668391 Return-Path: X-Original-To: patchwork-linux-arm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork2.web.kernel.org (Postfix) with ESMTP id 663C3C0553 for ; Fri, 25 Mar 2016 03:14:51 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 80BF120270 for ; Fri, 25 Mar 2016 03:14:50 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.9]) (using TLSv1.2 with cipher AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 974BF20222 for ; Fri, 25 Mar 2016 03:14:49 +0000 (UTC) Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1ajIBL-0001MI-6U; Fri, 25 Mar 2016 03:13:03 +0000 Received: from mx0b-0016f401.pphosted.com ([67.231.156.173]) by bombadil.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1ajIBI-0001Kk-3M for linux-arm-kernel@lists.infradead.org; Fri, 25 Mar 2016 03:13:00 +0000 Received: from pps.filterd (m0045851.ppops.net [127.0.0.1]) by mx0b-0016f401.pphosted.com (8.16.0.11/8.16.0.11) with SMTP id u2P3C3L4025537; Thu, 24 Mar 2016 20:12:35 -0700 Received: from sc-exch01.marvell.com ([199.233.58.181]) by mx0b-0016f401.pphosted.com with ESMTP id 21s69gq68g-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-SHA384 bits=256 verify=NOT); Thu, 24 Mar 2016 20:12:35 -0700 Received: from SC-EXCH04.marvell.com (10.93.176.84) by SC-EXCH01.marvell.com (10.93.176.81) with Microsoft SMTP Server (TLS) id 15.0.1104.5; Thu, 24 Mar 2016 20:12:33 -0700 Received: from maili.marvell.com (10.93.176.43) by SC-EXCH04.marvell.com (10.93.176.84) with Microsoft SMTP Server id 15.0.1104.5 via Frontend Transport; Thu, 24 Mar 2016 20:12:34 -0700 Received: from xhacker.marvell.com (unknown [10.37.135.134]) by maili.marvell.com (Postfix) with ESMTP id 134E43F7040; Thu, 24 Mar 2016 20:12:32 -0700 (PDT) From: Jisheng Zhang To: , , , Subject: [PATCH v2] arm64: cpuidle: make arm_cpuidle_suspend() a bit more efficient Date: Fri, 25 Mar 2016 11:08:55 +0800 Message-ID: <1458875335-1843-1-git-send-email-jszhang@marvell.com> X-Mailer: git-send-email 2.8.0.rc3 MIME-Version: 1.0 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:, , definitions=2016-03-25_01:, , signatures=0 X-Proofpoint-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=0 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1601100000 definitions=main-1603250046 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20160324_201300_289071_B6A4D683 X-CRM114-Status: GOOD ( 12.56 ) X-Spam-Score: -2.6 (--) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Jisheng Zhang , linux-kernel@vger.kernel.org, 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 X-Spam-Status: No, score=-4.2 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_MED, T_RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Currently, we check two pointers: cpu_ops and cpu_suspend on every idle state entry. These pointers check can be avoided: If cpu_ops has not been registered, arm_cpuidle_init() will return -EOPNOTSUPP, so arm_cpuidle_suspend() will never have chance to run. In other word, the cpu_ops check can be avoid. Similarly, the cpu_suspend check could be avoided in this hot path by moving it into arm_cpuidle_init(). I measured the 4096 * time from arm_cpuidle_suspend entry point to the cpu_psci_cpu_suspend entry point. HW platform is Marvell BG4CT STB board. 1. only one shell, no other process, hot-unplug secondary cpus, execute the following cmd while true do sleep 0.2 done before the patch: 1581220ns after the patch: 1579630ns reduced by 0.1% 2. only one shell, no other process, hot-unplug secondary cpus, execute the following cmd while true do md5sum /tmp/testfile sleep 0.2 done NOTE: the testfile size should be larger than L1+L2 cache size before the patch: 1961960ns after the patch: 1912500ns reduced by 2.5% So the more complex the system load, the bigger the improvement. Signed-off-by: Jisheng Zhang Acked-by: Lorenzo Pieralisi --- Since v1: - add performance numbers - combine two small patches into one - add Lorenzo's ack arch/arm64/kernel/cpuidle.c | 9 ++------- 1 file changed, 2 insertions(+), 7 deletions(-) diff --git a/arch/arm64/kernel/cpuidle.c b/arch/arm64/kernel/cpuidle.c index 9047cab6..e11857f 100644 --- a/arch/arm64/kernel/cpuidle.c +++ b/arch/arm64/kernel/cpuidle.c @@ -19,7 +19,8 @@ int __init arm_cpuidle_init(unsigned int cpu) { int ret = -EOPNOTSUPP; - if (cpu_ops[cpu] && cpu_ops[cpu]->cpu_init_idle) + if (cpu_ops[cpu] && cpu_ops[cpu]->cpu_suspend && + cpu_ops[cpu]->cpu_init_idle) ret = cpu_ops[cpu]->cpu_init_idle(cpu); return ret; @@ -36,11 +37,5 @@ int arm_cpuidle_suspend(int index) { int cpu = smp_processor_id(); - /* - * If cpu_ops have not been registered or suspend - * has not been initialized, cpu_suspend call fails early. - */ - if (!cpu_ops[cpu] || !cpu_ops[cpu]->cpu_suspend) - return -EOPNOTSUPP; return cpu_ops[cpu]->cpu_suspend(index); }