From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from dpdk.org (dpdk.org [92.243.14.124]) by inbox.dpdk.org (Postfix) with ESMTP id C7B90A046B for ; Thu, 22 Aug 2019 08:14:11 +0200 (CEST) Received: from [92.243.14.124] (localhost [127.0.0.1]) by dpdk.org (Postfix) with ESMTP id 3AD521BF73; Thu, 22 Aug 2019 08:13:43 +0200 (CEST) Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by dpdk.org (Postfix) with ESMTP id C8F031BF68 for ; Thu, 22 Aug 2019 08:13:39 +0200 (CEST) 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 59ED6360; Wed, 21 Aug 2019 23:13:39 -0700 (PDT) Received: from net-arm-thunderx2-01.test.ast.arm.com (net-arm-thunderx2-01.shanghai.arm.com [10.169.40.40]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 5D80C3F706; Wed, 21 Aug 2019 23:15:55 -0700 (PDT) From: Gavin Hu To: dev@dpdk.org Cc: nd@arm.com, thomas@monjalon.net, stephen@networkplumber.org, jerinj@marvell.com, pbhagavatula@marvell.com, Honnappa.Nagarahalli@arm.com Date: Thu, 22 Aug 2019 14:12:35 +0800 Message-Id: <1566454356-37277-6-git-send-email-gavin.hu@arm.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1566454356-37277-1-git-send-email-gavin.hu@arm.com> References: <1566454356-37277-1-git-send-email-gavin.hu@arm.com> In-Reply-To: <1561911676-37718-1-git-send-email-gavin.hu@arm.com> References: <1561911676-37718-1-git-send-email-gavin.hu@arm.com> Subject: [dpdk-dev] [PATCH v4 5/6] spinlock: use wfe to reduce contention on aarch64 X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" In acquiring a spinlock, cores repeatedly poll the lock variable. This is replaced by rte_wait_until_equal API. Running the micro benchmarking and the testpmd and l3fwd traffic tests on ThunderX2, Ampere eMAG80 and Arm N1SDP, everything went well and no notable performance gain nor degradation was measured. Signed-off-by: Gavin Hu Reviewed-by: Ruifeng Wang Reviewed-by: Phil Yang Reviewed-by: Steve Capper Reviewed-by: Ola Liljedahl Reviewed-by: Honnappa Nagarahalli Tested-by: Pavan Nikhilesh --- .../common/include/arch/arm/rte_spinlock.h | 25 ++++++++++++++++++++++ 1 file changed, 25 insertions(+) diff --git a/lib/librte_eal/common/include/arch/arm/rte_spinlock.h b/lib/librte_eal/common/include/arch/arm/rte_spinlock.h index 1a6916b..7b8328e 100644 --- a/lib/librte_eal/common/include/arch/arm/rte_spinlock.h +++ b/lib/librte_eal/common/include/arch/arm/rte_spinlock.h @@ -16,6 +16,31 @@ extern "C" { #include #include "generic/rte_spinlock.h" +/* armv7a does support WFE, but an explicit wake-up signal using SEV is + * required (must be preceded by DSB to drain the store buffer) and + * this is less performant, so keep armv7a implementation unchanged. + */ +#ifndef RTE_FORCE_INTRINSICS +static inline void +rte_spinlock_lock(rte_spinlock_t *sl) +{ + unsigned int tmp; + /* http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc. + * faqs/ka16809.html + */ + asm volatile( + "sevl\n" + "1: wfe\n" + "2: ldaxr %w[tmp], %w[locked]\n" + "cbnz %w[tmp], 1b\n" + "stxr %w[tmp], %w[one], %w[locked]\n" + "cbnz %w[tmp], 2b\n" + : [tmp] "=&r" (tmp), [locked] "+Q"(sl->locked) + : [one] "r" (1) + : "cc", "memory"); +} +#endif + static inline int rte_tm_supported(void) { return 0; -- 2.7.4