From mboxrd@z Thu Jan 1 00:00:00 1970 From: Shirley Ma Subject: Re: Network performance with small packets Date: Wed, 02 Feb 2011 07:39:45 -0800 Message-ID: <1296661185.25430.10.camel@localhost.localdomain> References: <20110201212411.GD30770@redhat.com> <1296595955.26937.822.camel@localhost.localdomain> <20110201214211.GB31105@redhat.com> <1296597185.26937.829.camel@localhost.localdomain> <20110201215603.GA31348@redhat.com> <1296601197.26937.833.camel@localhost.localdomain> <20110202044002.GB3818@redhat.com> <1296626748.26937.852.camel@localhost.localdomain> <1296627549.26937.856.camel@localhost.localdomain> <20110202104832.GA8505@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: Krishna Kumar2 , David Miller , kvm@vger.kernel.org, mashirle@linux.vnet.ibm.com, netdev@vger.kernel.org, netdev-owner@vger.kernel.org, Sridhar Samudrala , Steve Dobbelstein To: "Michael S. Tsirkin" Return-path: In-Reply-To: <20110202104832.GA8505@redhat.com> Sender: kvm-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Wed, 2011-02-02 at 12:48 +0200, Michael S. Tsirkin wrote: > Yes, I think doing this in the host is much simpler, > just send an interrupt after there's a decent amount > of space in the queue. > > Having said that the simple heuristic that I coded > might be a bit too simple. >>From the debugging out what I have seen so far (a single small message TCP_STEAM test), I think the right approach is to patch both guest and vhost. The problem I have found is a regression for single small message TCP_STEAM test. Old kernel works well for TCP_STREAM, only new kernel has problem. For Steven's problem, it's multiple stream TCP_RR issues, the old guest doesn't perform well, so does new guest kernel. We tested reducing vhost signaling patch before, it didn't help the performance at all. Thanks Shirley