From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759571Ab0J1Tco (ORCPT ); Thu, 28 Oct 2010 15:32:44 -0400 Received: from e4.ny.us.ibm.com ([32.97.182.144]:53697 "EHLO e4.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759407Ab0J1Tcj (ORCPT ); Thu, 28 Oct 2010 15:32:39 -0400 Subject: Re: [RFC PATCH 1/1] vhost: TX used buffer guest signal accumulation From: Shirley Ma To: "Michael S. Tsirkin" Cc: David Miller , netdev@vger.kernel.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org In-Reply-To: <20101028052021.GD5599@redhat.com> References: <1288216693.17571.38.camel@localhost.localdomain> <1288240804.14342.1.camel@localhost.localdomain> <20101028052021.GD5599@redhat.com> Content-Type: text/plain; charset="UTF-8" Date: Thu, 28 Oct 2010 12:32:35 -0700 Message-ID: <1288294355.11251.20.camel@localhost.localdomain> Mime-Version: 1.0 X-Mailer: Evolution 2.28.3 (2.28.3-1.fc12) Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 2010-10-28 at 07:20 +0200, Michael S. Tsirkin wrote: > My concern is this can delay signalling for unlimited time. > Could you pls test this with guests that do not have > 2b5bbe3b8bee8b38bdc27dd9c0270829b6eb7eeb > b0c39dbdc204006ef3558a66716ff09797619778 > that is 2.6.31 and older? The patch only induces delay signaling unlimited time when there is no TX packet to transmit. I thought TX signaling only noticing guest to release the used buffers, anything else beside this? I tested rhel5u5 guest (2.6.18 kernel), it works fine. I checked the two commits log, I don't think this patch could cause any issue w/o these two patches. Also I found a big TX regression for old guest and new guest. For old guest, I am able to get almost 11Gb/s for 2K message size, but for the new guest kernel, I can only get 3.5 Gb/s with the patch and same host. I will dig it why. thanks Shirley