From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f66.google.com (mail-wm0-f66.google.com [74.125.82.66]) by dpdk.org (Postfix) with ESMTP id 36D492082 for ; Wed, 28 Feb 2018 10:27:51 +0100 (CET) Received: by mail-wm0-f66.google.com with SMTP id 188so3668563wme.1 for ; Wed, 28 Feb 2018 01:27:51 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=6wind-com.20150623.gappssmtp.com; s=20150623; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:content-transfer-encoding:in-reply-to :user-agent; bh=EgL63mAchIL/0uvqPYE7eMD6nXn2ghTILFEBe7x60JA=; b=JQiI1VqCsFmFnp97ELh2u67m3uVSANuWdF5max4I4nlKH5XhnJhe6NL/WYTX0yU/+6 caV9n23PSZ6QEUpyxPwbiZd6SrIfXIOFmxdapDeBq/JRYdEQCLLGkA6O47iZW/phnqej 1MOd6rRDo+94/Oa++HBCemgOkBKBjy0soDCQAlwdXnn8L6BnSjDDjQ46hFDLkUOY+1r8 VvJnLqaHaNvc7W8bAVxPB3Irq4PQV5TjveIU8IddYK8YX1Bn5jMwkpe02HgFxkno/BCT r2m2C/gQ0ijzKgx6i2TlfSxQANLOadCzNx0uxQQvL1tVESosHiLMl7MYpMvcrJO0FP0K ICUg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:content-transfer-encoding :in-reply-to:user-agent; bh=EgL63mAchIL/0uvqPYE7eMD6nXn2ghTILFEBe7x60JA=; b=PRHuid16gAHX2UT2L8CURMPhaeky58/oWOiSOS4RyK4KF22gXUbbPwX5Jt0qjTi6D6 ix/4mzUoZoUX7FvZmOwUknbSWUBpq6dzgy4r5uH+v1M9KnkajGqUFzUpXa/TxlXxPaoP bhZ17PH8qibbBO8bOzGNq2Zx4RHloJNU0gQeGns3VWiQqIPwE0ee7+5XszKgaZpF97Va sa53wdJBiaN/eOawPfNpqa0ibeV7g5JhHb7FKF+cHuOT72+5r1LJw4FMK5SeQKz8HPLu 3Oo8Ny/PgG38eAas93OEuyi0wjklMonGv7U8/dRByY1535XeAwGHqhSX5K7CxJv9IA1v 8QzA== X-Gm-Message-State: APf1xPD7oAYMNpzc/xYzkKU37TgxUq92lmTYxqbIxHQ61zXo3yFvP92s N3E7/NW6mRcJamAP25LY9+qE9Q== X-Google-Smtp-Source: AG47ELsOz2i8rgxvk28A03SP2slsK3dH1/tJb3GRTHwePIN8mlGtKl3XMMaHy4ehwhGaIqF4/3u/0Q== X-Received: by 10.28.15.4 with SMTP id 4mr4644664wmp.33.1519810070545; Wed, 28 Feb 2018 01:27:50 -0800 (PST) Received: from bidouze.vm.6wind.com (host.78.145.23.62.rev.coltfrance.com. [62.23.145.78]) by smtp.gmail.com with ESMTPSA id d27sm1167149wrd.60.2018.02.28.01.27.49 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Wed, 28 Feb 2018 01:27:49 -0800 (PST) Date: Wed, 28 Feb 2018 10:27:28 +0100 From: =?iso-8859-1?Q?Ga=EBtan?= Rivet To: Yuliang Li Cc: users@dpdk.org Message-ID: <20180228092728.ezf2zic2vjfpzalq@bidouze.vm.6wind.com> References: MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: NeoMutt/20170113 (1.7.2) Subject: Re: [dpdk-users] occasionally ~300us delay X-BeenThere: users@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: DPDK usage discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 28 Feb 2018 09:27:51 -0000 Hi, On Wed, Feb 28, 2018 at 12:03:30AM -0500, Yuliang Li wrote: > Also, such pause happens regularly--every 0.5s. > > On Wed, Feb 28, 2018 at 12:01 AM, Yuliang Li wrote: > > > Hi all, > > > > I am using dpdk to generate packets. Specifically, I have a list of > > , meaning I want to send Pi at Ti. I wait for Ti by while > > (rte_get_tsc_cycles() > 300us of sending packets, i.e., the sending time of some Pi is around > > Ti+300us. It looks like the program just pauses by 300us, and then resumes. > > Does anyone know why? > > > > Thanks, > I would reduce entropy and gather more data. You can isolate your process (i.e. numactl), if possible not on core 0, disable hyper-threading, disable CPU frequency scaling. Then, running your app: # grep ctxt_sw /proc/$(pidof your-dpdk-app)/status If you have context switches, then you have other tasks throwing off your measures. The rte-intr-thread is notorious for having bad affinities and triggering context switches, and can be used for alarms (thus, possible regular occurence). Regards, -- Gaëtan Rivet 6WIND