From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eelco Chaudron Subject: Re: [PATCH] app/testpmd: adds mlockall() to fix pages Date: Thu, 21 Sep 2017 14:24:28 +0200 Message-ID: References: <22990026376b08418cb0eb6f028840c03e89f47f.1505221429.git.echaudro@redhat.com> <4147502.SWF1kaKTU5@xps> <2ff0680b-b73f-fd1f-9f41-caa38a13bcde@redhat.com> <20170919072818.zbhjsfhpbqf4fqxz@neon> Reply-To: echaudro@redhat.com Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Cc: Thomas Monjalon , dev@dpdk.org, jingjing.wu@intel.com To: Olivier MATZ Return-path: Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28]) by dpdk.org (Postfix) with ESMTP id 677DE1B1A2 for ; Thu, 21 Sep 2017 14:24:17 +0200 (CEST) In-Reply-To: <20170919072818.zbhjsfhpbqf4fqxz@neon> Content-Language: en-US List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" On 19/09/17 09:28, Olivier MATZ wrote: > Hi, > > On Thu, Sep 14, 2017 at 09:22:38AM +0200, Eelco Chaudron wrote: >> On 13/09/17 11:39, Thomas Monjalon wrote: >>> 12/09/2017 15:08, Eelco Chaudron: >>>> Call the mlockall() function, to attempt to lock all of its process >>>> memory into physical RAM, and preventing the kernel from paging any >>>> of its memory to disk. >>>> >>>> When using testpmd for performance testing, depending on the code path >>>> taken, we see a couple of page faults in a row. These faults effect >>>> the overall drop-rate of testpmd. On Linux the mlockall() call will >>>> prefault all the pages of testpmd (and the DPDK libraries if linked >>>> dynamically), even without LD_BIND_NOW. >>> Does it work on FreeBSD? >> I do not have a FreeBSD setup, but from the documentation I've read the call >> is supported by FreeBSD. >> If some one has a working setup, please give this patch a quick try. >>> Is there any drawback? >>> Do we need to add an option for it? >> The only drawback I can think of is that with this change memory phyiscal >> memory is consumed as pages are pre-loaded. >> For testpmd (just loaded not doing anything) this is 2MB vs 35MB of memory >> used. I do not think this yields an extra option. > One small comment: the call to mlockall() will fail if we don't have > the permissions. I guess it's not an issue, but I wonder if we should > log it? I did not at add a log, as the rte log subsystem is not yet initialized. However we could add a printf("WARNING: mlockall() failed with error %s") like message. What do you think? > Olivier