From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751842Ab3HTCdO (ORCPT ); Mon, 19 Aug 2013 22:33:14 -0400 Received: from mx1.redhat.com ([209.132.183.28]:50661 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751254Ab3HTCdN (ORCPT ); Mon, 19 Aug 2013 22:33:13 -0400 Message-ID: <5212D564.80200@redhat.com> Date: Tue, 20 Aug 2013 10:33:08 +0800 From: Jason Wang User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130803 Thunderbird/17.0.8 MIME-Version: 1.0 To: "Michael S. Tsirkin" CC: kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/6] vhost_net: use vhost_add_used_and_signal_n() in vhost_zerocopy_signal_used() References: <1376630190-5912-1-git-send-email-jasowang@redhat.com> <1376630190-5912-3-git-send-email-jasowang@redhat.com> <20130816095426.GA21821@redhat.com> In-Reply-To: <20130816095426.GA21821@redhat.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 08/16/2013 05:54 PM, Michael S. Tsirkin wrote: > On Fri, Aug 16, 2013 at 01:16:26PM +0800, Jason Wang wrote: >> > Switch to use vhost_add_used_and_signal_n() to avoid multiple calls to >> > vhost_add_used_and_signal(). With the patch we will call at most 2 times >> > (consider done_idx warp around) compared to N times w/o this patch. >> > >> > Signed-off-by: Jason Wang > So? Does this help performance then? > Looks like it can especially when guest does support event index. When guest enable tx interrupt, this can saves us some unnecessary signal to guest. I will do some test.