From patchwork Tue May 5 21:17:27 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Honnappa Nagarahalli X-Patchwork-Id: 186216 Delivered-To: patch@linaro.org Received: by 2002:a92:8d81:0:0:0:0:0 with SMTP id w1csp1514514ill; Tue, 5 May 2020 14:17:55 -0700 (PDT) X-Google-Smtp-Source: APiQypJkdA9Au5OBp3FgK5xZszarJH8KRIX2SOyiCZhhBfOK19MtjzR2DUCDvc1A8pMTO3wmIo2q X-Received: by 2002:a17:906:af6f:: with SMTP id os15mr4742826ejb.78.1588713475740; Tue, 05 May 2020 14:17:55 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1588713475; cv=none; d=google.com; s=arc-20160816; b=wKjQSOKUHdAdeEdKSz3A2G8HvhqL4HjW2gvSBQGotDiy88JpAKbUlUjC82s2XqGOGz A9jRj57T0NVwQIMIchWPEWLccIq3Mp3B2Yu/6SbPX7KMGQthPEBMmO4SChQaO+MAQT0n kJxuJkRtj5u8zBZRxUqiPZts+L6c87hfZIC8FC4J5Xg5r2oYVwcj0DlAIoTAtd6+BAL/ 82EkUMa4GYUy1XoCt3Y1sWqdYdw6MgXfsxiSCqBQd4CTdlWCRKoDg5YvS9XHLzzJKItc uptwE8G4AeMCG0LxQJ2b1QnV4Pgp2b/4Nit53f12cWNUmxMhH0U4rEFkoJHwn6vzUzMb 22Eg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=sender:errors-to:list-subscribe:list-help:list-post:list-archive :list-unsubscribe:list-id:precedence:subject:references:in-reply-to :message-id:date:cc:to:from; bh=+qKXhvC0ka0dyayRHqoam2LVsI5nkDrJVrxliChQm88=; b=kvGJCc907o33IVavpHBa9Y1GFbXtsqd0mEbudhJikODUniwTBZfHTo8lfQ5Sb5XhDM 1QbCnrRuWK8z4gmiChIPlqbmCFOVNpw7rbd2PjtENQL3ZKArs2SU3KGunVYBHxiH/p/u yZuPZ0qn6bzwf5LiXOf46e2O978mfV9OEoG5MANrRglHdnPNTWGciVFwSFnBybpMS4zg oRCHI7V4qCIcaWcEfadwurM5jAA+HRk/XbQzGzxct2jqI63G3kYQiz1Ki9T9qApZYucj 8gQ8JHfunOyTeqsOvJYN3uLwPATdRriNBPu8URDOiI54jG1yjaTrXtaVkWOM8uqYyQJl Xapw== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: domain of dev-bounces@dpdk.org designates 92.243.14.124 as permitted sender) smtp.mailfrom=dev-bounces@dpdk.org Return-Path: Received: from dpdk.org (dpdk.org. [92.243.14.124]) by mx.google.com with ESMTP id jz18si1830871ejb.112.2020.05.05.14.17.55; Tue, 05 May 2020 14:17:55 -0700 (PDT) Received-SPF: pass (google.com: domain of dev-bounces@dpdk.org designates 92.243.14.124 as permitted sender) client-ip=92.243.14.124; Authentication-Results: mx.google.com; spf=pass (google.com: domain of dev-bounces@dpdk.org designates 92.243.14.124 as permitted sender) smtp.mailfrom=dev-bounces@dpdk.org Received: from [92.243.14.124] (localhost [127.0.0.1]) by dpdk.org (Postfix) with ESMTP id 0C1461D69C; Tue, 5 May 2020 23:17:51 +0200 (CEST) Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by dpdk.org (Postfix) with ESMTP id 310A41D69A; Tue, 5 May 2020 23:17:49 +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 7AF6F31B; Tue, 5 May 2020 14:17:48 -0700 (PDT) Received: from qc2400f-1.austin.arm.com (qc2400f-1.austin.arm.com [10.118.14.48]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 652CB3F305; Tue, 5 May 2020 14:17:48 -0700 (PDT) From: Honnappa Nagarahalli To: dev@dpdk.org, phil.yang@arm.com, harry.van.haaren@intel.com Cc: thomas@monjalon.net, david.marchand@redhat.com, konstantin.ananyev@intel.com, jerinj@marvell.com, hemant.agrawal@nxp.com, gage.eads@intel.com, bruce.richardson@intel.com, honnappa.nagarahalli@arm.com, nd@arm.com, stable@dpdk.org Date: Tue, 5 May 2020 16:17:27 -0500 Message-Id: <20200505211732.25291-2-honnappa.nagarahalli@arm.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20200505211732.25291-1-honnappa.nagarahalli@arm.com> References: <1587659482-27133-1-git-send-email-phil.yang@arm.com> <20200505211732.25291-1-honnappa.nagarahalli@arm.com> Subject: [dpdk-dev] [PATCH v4 1/6] service: fix race condition for MT unsafe service 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" The MT unsafe service might get configured to run on another core while the service is running currently. This might result in the MT unsafe service running on multiple cores simultaneously. Use 'execute_lock' always when the service is MT unsafe. If the service is known to be mmapped on a single lcore, setting the service capability to MT safe will avoid taking the lock and improve the performance. Fixes: e9139a32f6e8 ("service: add function to run on app lcore") Cc: stable@dpdk.org Signed-off-by: Honnappa Nagarahalli Reviewed-by: Phil Yang Acked-by: Harry van Haaren --- lib/librte_eal/common/rte_service.c | 11 +++++------ lib/librte_eal/include/rte_service.h | 8 ++++++-- lib/librte_eal/include/rte_service_component.h | 6 +++++- 3 files changed, 16 insertions(+), 9 deletions(-) -- 2.17.1 diff --git a/lib/librte_eal/common/rte_service.c b/lib/librte_eal/common/rte_service.c index 70d17a5d7..b8c465eb9 100644 --- a/lib/librte_eal/common/rte_service.c +++ b/lib/librte_eal/common/rte_service.c @@ -50,6 +50,10 @@ struct rte_service_spec_impl { uint8_t internal_flags; /* per service statistics */ + /* Indicates how many cores the service is mapped to run on. + * It does not indicate the number of cores the service is running + * on currently. + */ rte_atomic32_t num_mapped_cores; uint64_t calls; uint64_t cycles_spent; @@ -370,12 +374,7 @@ service_run(uint32_t i, struct core_state *cs, uint64_t service_mask, cs->service_active_on_lcore[i] = 1; - /* check do we need cmpset, if MT safe or <= 1 core - * mapped, atomic ops are not required. - */ - const int use_atomics = (service_mt_safe(s) == 0) && - (rte_atomic32_read(&s->num_mapped_cores) > 1); - if (use_atomics) { + if (service_mt_safe(s) == 0) { if (!rte_atomic32_cmpset((uint32_t *)&s->execute_lock, 0, 1)) return -EBUSY; diff --git a/lib/librte_eal/include/rte_service.h b/lib/librte_eal/include/rte_service.h index d8701dd4c..3a1c735c5 100644 --- a/lib/librte_eal/include/rte_service.h +++ b/lib/librte_eal/include/rte_service.h @@ -104,12 +104,16 @@ int32_t rte_service_probe_capability(uint32_t id, uint32_t capability); * Each core can be added or removed from running a specific service. This * function enables or disables *lcore* to run *service_id*. * - * If multiple cores are enabled on a service, an atomic is used to ensure that - * only one cores runs the service at a time. The exception to this is when + * If multiple cores are enabled on a service, a lock is used to ensure that + * only one core runs the service at a time. The exception to this is when * a service indicates that it is multi-thread safe by setting the capability * called RTE_SERVICE_CAP_MT_SAFE. With the multi-thread safe capability set, * the service function can be run on multiple threads at the same time. * + * If the service is known to be mapped to a single lcore, setting the + * capability of the service to RTE_SERVICE_CAP_MT_SAFE can achieve + * better performance by avoiding the use of lock. + * * @param service_id the service to apply the lcore to * @param lcore The lcore that will be mapped to service * @param enable Zero to unmap or disable the core, non-zero to enable diff --git a/lib/librte_eal/include/rte_service_component.h b/lib/librte_eal/include/rte_service_component.h index 16eab79ee..b75aba11b 100644 --- a/lib/librte_eal/include/rte_service_component.h +++ b/lib/librte_eal/include/rte_service_component.h @@ -43,7 +43,7 @@ struct rte_service_spec { /** * Register a new service. * - * A service represents a component that the requires CPU time periodically to + * A service represents a component that requires CPU time periodically to * achieve its purpose. * * For example the eventdev SW PMD requires CPU cycles to perform its @@ -56,6 +56,10 @@ struct rte_service_spec { * *rte_service_component_runstate_set*, which indicates that the service * component is ready to be executed. * + * If the service is known to be mapped to a single lcore, setting the + * capability of the service to RTE_SERVICE_CAP_MT_SAFE can achieve + * better performance. + * * @param spec The specification of the service to register * @param[out] service_id A pointer to a uint32_t, which will be filled in * during registration of the service. It is set to the integers