From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f68.google.com (mail-wm0-f68.google.com [74.125.82.68]) by dpdk.org (Postfix) with ESMTP id 9E3591B6C1 for ; Fri, 10 Nov 2017 11:42:58 +0100 (CET) Received: by mail-wm0-f68.google.com with SMTP id b14so1808474wme.2 for ; Fri, 10 Nov 2017 02:42:58 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=ESiH7qNzFYquwmGVvy+O0z329jfgI/HNvVnOq+GACS4=; b=VqQfx/HyI6RdnzCTUvxczINVsrgHY5kp+srbyxy8U6lsIunjCXLo4mFRayYVwnJHup v+RFs+30GJb5D/CPjT40xsA9B4IFBrIbqCaHezN8CDYR4o/cwy1jB6lg0BSJEMPdjU4E FCr6//+iLIp2i0BTDwFesdbepGERzRVM35X32gfQPsrOOOjmTyYpxKhCG8Ckleo7VAvP onz5l4A+yHEbW7lCo/WbFfKFkvUG1xAVpKKJCbQZj7rt/ar1qnNzBxzHkeoeeqjJAQwr x+qDw0qKcmb5YsBbtW73d2X/uXA8Yuxc02DdiDnL/h2yTcbCOymK+ZSwuwNyfbn/0+3P BmfA== X-Gm-Message-State: AJaThX77eFofgh60SpKDQdHBo+8dUgpPnZPnweOtRO2sfXfXbIptbEa5 Z1cq5fno/PG947sGcNjCsPApyQ== X-Google-Smtp-Source: AGs4zMaCXgL030SuYuVx+oXO3JcxodMup1kuj/+Anokx23ryLABC7p9CSvITyceHNbcLUKPibQjY4A== X-Received: by 10.80.228.65 with SMTP id e1mr1920231edm.245.1510310578281; Fri, 10 Nov 2017 02:42:58 -0800 (PST) Received: from t460s.bristot.redhat.com ([193.205.81.200]) by smtp.gmail.com with ESMTPSA id f53sm790220ede.86.2017.11.10.02.42.57 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 10 Nov 2017 02:42:57 -0800 (PST) To: "Ananyev, Konstantin" , Adrien Mazarguil , Marcelo Tosatti Cc: "dev@dpdk.org" , Luiz Capitulino References: <20171110060210.GA23340@amt.cnet> <20171110091219.GE24849@6wind.com> <2601191342CEEE43887BDE71AB9772585FABBC64@irsmsx105.ger.corp.intel.com> From: Daniel Bristot de Oliveira Message-ID: Date: Fri, 10 Nov 2017 11:42:56 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.4.0 MIME-Version: 1.0 In-Reply-To: <2601191342CEEE43887BDE71AB9772585FABBC64@irsmsx105.ger.corp.intel.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Subject: Re: [dpdk-dev] [PATCH] testpmd: add nanosleep in main loop 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: , X-List-Received-Date: Fri, 10 Nov 2017 10:42:58 -0000 On 11/10/2017 11:14 AM, Ananyev, Konstantin wrote: > Agree with Adrian here - the patch doesn't fix the problem in any case, I would agree with you if it were possible to assume one can fully isolate a CPU on Linux... but it is not... This: https://lwn.net/Articles/659490/ is still an open issue, and the reason why it is an open issue is the kernel threads that need to run on every CPU, mainly when using the PREEMPT_RT, which turns almost everything on threads. > while introducing an unnecessary slowdown in testpmd iofwd mode. > Please think up some other approach. The other approach is to increase the priority of all other threads that run on the isolate CPU. But that is not a good idea at all, as the other threads might preempt the busy-loop thread at the worst possible moment. Using the knowledge of the thread about when it is the best time to give a chance for other threads to run would be a smarter decision. -- Daniel