From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752523AbcERIQj (ORCPT ); Wed, 18 May 2016 04:16:39 -0400 Received: from mx1.redhat.com ([209.132.183.28]:46459 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752397AbcERIQg (ORCPT ); Wed, 18 May 2016 04:16:36 -0400 Date: Wed, 18 May 2016 10:16:31 +0200 From: Jesper Dangaard Brouer To: Jason Wang Cc: brouer@redhat.com, "Michael S. Tsirkin" , davem@davemloft.net, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH net-next] tuntap: introduce tx skb ring Message-ID: <20160518101631.368e3447@redhat.com> In-Reply-To: <573A761D.8080909@redhat.com> References: <1463361421-4397-1-git-send-email-jasowang@redhat.com> <20160516070012-mutt-send-email-mst@redhat.com> <57397C2B.7000603@redhat.com> <20160516105434-mutt-send-email-mst@redhat.com> <573A761D.8080909@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.31]); Wed, 18 May 2016 08:16:35 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 17 May 2016 09:38:37 +0800 Jason Wang wrote: > >> And if tx_queue_length is not power of 2, > >> we probably need modulus to calculate the capacity. > > Is that really that important for speed? > > Not sure, I can test. In my experience, yes, adding a modulus does affect performance. > > If yes, round it up to next power of two. > > Right, this sounds a good solution. Good idea. -- Best regards, Jesper Dangaard Brouer MSc.CS, Principal Kernel Engineer at Red Hat Author of http://www.iptv-analyzer.org LinkedIn: http://www.linkedin.com/in/brouer