From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mails.dpdk.org (mails.dpdk.org [217.70.189.124]) by inbox.dpdk.org (Postfix) with ESMTP id 3724942503 for ; Wed, 6 Sep 2023 01:29:34 +0200 (CEST) Received: from mails.dpdk.org (localhost [127.0.0.1]) by mails.dpdk.org (Postfix) with ESMTP id B360940DDE; Wed, 6 Sep 2023 01:29:33 +0200 (CEST) Received: from mail-pl1-f174.google.com (mail-pl1-f174.google.com [209.85.214.174]) by mails.dpdk.org (Postfix) with ESMTP id 115E6406B7 for ; Wed, 6 Sep 2023 01:29:32 +0200 (CEST) Received: by mail-pl1-f174.google.com with SMTP id d9443c01a7336-1c1ff5b741cso24069075ad.2 for ; Tue, 05 Sep 2023 16:29:31 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=networkplumber-org.20230601.gappssmtp.com; s=20230601; t=1693956571; x=1694561371; darn=dpdk.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:subject:cc:to:from:date:from:to:cc:subject:date :message-id:reply-to; bh=ZjuhQAvbPM27kSjswCd+9m0xh+dMqVzLXDV2QBoVLZc=; b=FedEnwe0PgfaIu9EhHXXNVISyTz0WEXOX0VEAJzAV6xWdvdIHjiww+q93b6I7bYm7m NWLeGeXDWfZU6a9VcYcP+hr7wE/mpwramGYljLl3FWvRUeT4CVV8AeyvIDcpHAimjeqp 5ZwQQBH13MLeUUltRwW1hM7Lb3G1U/dzXLz8g+Bwoy54nYBzxjpf6esQVG1doQ91Ou5Z EK3OJNzy9hadoSergKjHsPiEPeeA4Ksujikm75OGxoBFK/bXKldi8ejfMoZpB6bSwH5d Yh+9T0qPFhgE5URfairnScsG2Lw8YIBrzTCwjfWzfaozjxKvepOl5OR0btz47yCf3nAi b8OA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1693956571; x=1694561371; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:subject:cc:to:from:date:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=ZjuhQAvbPM27kSjswCd+9m0xh+dMqVzLXDV2QBoVLZc=; b=cUya44I8+zYDGYvNGTqiy96w2wMlb7iaOVwtmYZKH2QOsqUW/l3JMxOJK4P5Xh1Abe eACQn+hi2umgsT2bjiEx4wpEnjWOpvDhSJ9LHG74mizaJzptQmV2wavvv0zCMRUjdjq0 bl8wDE6wQZ2KxuV581uUViRQ2kkSuBTENZrtdBsxDvtsp5djbJ9FYDg2joso5PI4Egxf KSnDfSRFloFaUwU5uu6XegiuWWO/1+i5qQdRGjfFLOl/Vxn1HJz482xIDb5/ba+CcAgM EJ67XUGk04yTvavbZEAza7YghFB2pz55V/9Yc6q8CGRUBJeqhVIzL7zSzwl/JS3TPson qt+g== X-Gm-Message-State: AOJu0YzsRTNjFhpb4dRbwdGFe7+lpDQvPzUVD2lbnbsYrfDTQ94l/ZH4 seiM/EqyFaG8UmhR48ow7PTmeg== X-Google-Smtp-Source: AGHT+IHxLuJROvgFl53OgPmkaSZaapeyjAQudDfsE8XVODecZKFmdDPbw47A2Hk3Q1AKRLm9jJg0Gg== X-Received: by 2002:a17:902:be05:b0:1bd:d6b5:a54f with SMTP id r5-20020a170902be0500b001bdd6b5a54fmr13917570pls.55.1693956570892; Tue, 05 Sep 2023 16:29:30 -0700 (PDT) Received: from hermes.local (204-195-112-131.wavecable.com. [204.195.112.131]) by smtp.gmail.com with ESMTPSA id t23-20020a1709028c9700b001bb515e6b39sm9775154plo.306.2023.09.05.16.29.30 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 05 Sep 2023 16:29:30 -0700 (PDT) Date: Tue, 5 Sep 2023 16:29:29 -0700 From: Stephen Hemminger To: Hari Haran Cc: users@dpdk.org Subject: Re: rte_rdtsc() - what is the performance impact of using rte_rdtsc() time Message-ID: <20230905162929.3dbc9e12@hermes.local> In-Reply-To: References: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-BeenThere: users@dpdk.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: DPDK usage discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: users-bounces@dpdk.org On Tue, 29 Aug 2023 20:25:54 +0530 Hari Haran wrote: > Hi All, > > Subject: rte_rdtsc() - what is the performance impact of using rte_rdtsc() > time under lcore thread while(1) > > Requirement: > > 1. Store the packet received timestamp - based on it packets will be > removed from buffer if it exceeds the threshold timer of buffer > 2. Two threads are available, One is lcore(dedicated core) and another > is pthread(not a dedicated core. In pthread, have to get the timestamp of > last received packet timestamp > > > Query: > > 1. For every packet reception in lcore thread under while(1), will get > the packet received timestamp using rte_rdtsc() function. Whether usage of > rte_rdtsc() function adds more delay in packet processing? > 2. Is there any way to convert rte_rdtsc() timestamp value to current > system time in pthread()? In pthread, the last packet received time needed > in the form of system time. > > > Thanks in advance. > > Regards, > Hariharan The problem is that rte_rdtsc() stops speculative execution so doing lots of TSC instructions can hurt performance. To correlate TSC timestamp to system time, you need to compute the offsets once at startup. Alternatively, don't use rte_rdtsc() and instead use clock_gettime() with the monotonic timer and the C library does the calculation for you.