From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michael S. Tsirkin" Subject: Re: [PATCH 1/2] vhost: allow multiple workers threads Date: Tue, 21 Feb 2012 05:21:48 +0200 Message-ID: <20120221032147.GB2502@redhat.com> References: <1329519726-25763-1-git-send-email-aliguori@us.ibm.com> <1329519726-25763-2-git-send-email-aliguori@us.ibm.com> <20120219144145.GA16620@redhat.com> <20120220192708.GA18308@redhat.com> <4F42A2FB.7000501@us.ibm.com> <20120220210005.GA19278@redhat.com> <1329786250.13141.9.camel@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Anthony Liguori , Tom Lendacky , netdev@vger.kernel.org, Cristian Viana To: Shirley Ma Return-path: Received: from mx1.redhat.com ([209.132.183.28]:19658 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751478Ab2BUDVt (ORCPT ); Mon, 20 Feb 2012 22:21:49 -0500 Content-Disposition: inline In-Reply-To: <1329786250.13141.9.camel@localhost.localdomain> Sender: netdev-owner@vger.kernel.org List-ID: On Mon, Feb 20, 2012 at 05:04:10PM -0800, Shirley Ma wrote: > On Mon, 2012-02-20 at 23:00 +0200, Michael S. Tsirkin wrote: > > > > The point was really to avoid scheduler overhead > > as with tcp, tx and rx tend to run on the same cpu. > > We have tried different approaches in the past, like splitting vhost > thread to separate TX, RX threads; create per cpu vhost thread instead > of creating per VM per virtio_net vhost thread... > > We think per cpu vhost thread is a better approach based on the data we > have collected. It will reduce both vhost resource and scheduler > overhead. It will not depend on host scheduler, has less various. The > patch is under testing, we hope we can post it soon. > > Thanks > Shirley Yes, great, this is definitely interesting. I actually started with a per-cpu one - it did not perform well but I did not figure out why, switching to a single thread fixed it and I did not dig into it. -- MST