From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Dumazet Subject: Re: [net-next patch 8/12] bnx2x: Allow up to 63 RSS queues default 8 queues Date: Wed, 13 Jun 2012 15:59:15 +0200 Message-ID: <1339595955.22704.352.camel@edumazet-glaptop> References: <1339591464-10554-1-git-send-email-meravs@broadcom.com> <1339591464-10554-9-git-send-email-meravs@broadcom.com> <1339581175.22704.342.camel@edumazet-glaptop> <1339600460.17240.69.camel@lb-tlvb-meravs.il.broadcom.com> <1339595609.13000.15.camel@lb-tlvb-eilong.il.broadcom.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: Merav Sicron , davem@davemloft.net, netdev@vger.kernel.org To: eilong@broadcom.com Return-path: Received: from mail-ey0-f174.google.com ([209.85.215.174]:43718 "EHLO mail-ey0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753671Ab2FMN7X (ORCPT ); Wed, 13 Jun 2012 09:59:23 -0400 Received: by eaak11 with SMTP id k11so216372eaa.19 for ; Wed, 13 Jun 2012 06:59:22 -0700 (PDT) In-Reply-To: <1339595609.13000.15.camel@lb-tlvb-eilong.il.broadcom.com> Sender: netdev-owner@vger.kernel.org List-ID: On Wed, 2012-06-13 at 16:53 +0300, Eilon Greenstein wrote: > On Wed, 2012-06-13 at 18:14 +0300, Merav Sicron wrote: > > Hi Eric, > > > > On Wed, 2012-06-13 at 11:52 +0200, Eric Dumazet wrote: > > > On Wed, 2012-06-13 at 15:44 +0300, Merav Sicron wrote: > > > > This patch removed the limitation in the code for 16 RSS queues. The default > > > > (without other instruction from the user) number of queues is determined > > > > according to the number of MSI-X vectors supported for that function, the number > > > > of CPUs in the system, and a maximum of 8 queues. > > > > > > Thats a very confusing changelog > > > > > > You meant : " a minimum of 8 queues" ? > > > > > No, I meant maximum...for example in a system with 16 CPUs we will > > allocate 8 RSS queues. We saw that in most scenarios we tested there was > > no need for more than 8 queues to get the maximal throughput, and by > > limiting to 8 by default we reduce the allocated memory. We do provide > > ethtool -L support so that the user could request more RSS queues if > > desired. > > > > > You should give more explanations, because its a sensible area for > > > performances. > > > > > Just to emphasis, since this is the patch series that enable the users > to control the number of queues, we can reduce the default number and > allow the user to increase it if he has a setup that needs more than 8 > parallel CPUs to receive the traffic. When using a new FW on the board, > the number can be increased up to 64, so using the maximal number can be > an overkill (even if the machine has 64 CPUs, it does not mean that the > user would like us to consume 64 MSI-X vectors and all the memory to set > up 64 queues) - so a lower default value can be used to satisfy most > users while allowing them to increase the number if they wish. I am all for a reduction of default number of queues. Even a laptop has now 8 cpus, so on servers, using one queue per cpu is overkill for most uses. Thanks