From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753174Ab0LFExH (ORCPT ); Sun, 5 Dec 2010 23:53:07 -0500 Received: from ozlabs.org ([203.10.76.45]:48702 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752863Ab0LFExG (ORCPT ); Sun, 5 Dec 2010 23:53:06 -0500 From: Rusty Russell To: "Michael S. Tsirkin" Subject: Re: [PATCH 2/2] tools/virtio: virtio_test tool Date: Mon, 6 Dec 2010 15:23:02 +1030 User-Agent: KMail/1.13.5 (Linux/2.6.35-23-generic; KDE/4.5.1; i686; ; ) Cc: virtualization@lists.linux-foundation.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org References: <20101129170431.GA4027@redhat.com> <20101129171637.GC4027@redhat.com> In-Reply-To: <20101129171637.GC4027@redhat.com> MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Message-Id: <201012061523.03108.rusty@rustcorp.com.au> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 30 Nov 2010 03:46:37 am Michael S. Tsirkin wrote: > This is the userspace part of the tool: it includes a bunch of stubs for > linux APIs, somewhat simular to linuxsched. This makes it possible to > recompile the ring code in userspace. > > A small test example is implemented combining this with vhost_test > module. > > Signed-off-by: Michael S. Tsirkin Hi Michael, I'm not sure what the point is of this work? You'll still need to benchmark on real systems, but it's not low-level enough to measure things like cache misses. I'm assuming you're thinking of playing with layout to measure cache behaviour. I was thinking of a complete userspace implementation where either it was run under cachegrind, or each access was wrapped to allow tracking of cachelines to give an exact measure of cache movement under various scenarios (esp. ring mostly empty, ring in steady state, ring mostly full). Cheers, Rusty.