Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756286AbZLWPSb (ORCPT ); Wed, 23 Dec 2009 10:18:31 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755372AbZLWPSa (ORCPT ); Wed, 23 Dec 2009 10:18:30 -0500 Received: from sous-sol.org ([216.99.217.87]:36428 "EHLO sequoia.sous-sol.org" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750753AbZLWPS3 (ORCPT ); Wed, 23 Dec 2009 10:18:29 -0500 Date: Wed, 23 Dec 2009 07:17:22 -0800 From: Chris Wright To: Anthony Liguori Cc: Chris Wright , Andi Kleen , Gregory Haskins , Avi Kivity , Ingo Molnar , kvm@vger.kernel.org, Andrew Morton , torvalds@linux-foundation.org, "linux-kernel@vger.kernel.org" , netdev@vger.kernel.org, "alacrityvm-devel@lists.sourceforge.net" Subject: Re: [GIT PULL] AlacrityVM guest drivers for 2.6.33 Message-ID: <20091223151722.GB6518@sequoia.sous-sol.org> References: <4B2FB3F1.5080808@gmail.com> <4B300EF8.8010602@codemonkey.ws> <87637zdy9g.fsf@basil.nowhere.org> <4B30E654.40702@codemonkey.ws> <20091222162110.GG10314@basil.fritz.box> <4B30F375.6050103@codemonkey.ws> <20091222173326.GH10314@basil.fritz.box> <4B3136AA.50204@codemonkey.ws> <20091223000210.GA6518@sequoia.sous-sol.org> <4B323353.8000607@codemonkey.ws> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4B323353.8000607@codemonkey.ws> User-Agent: Mutt/1.5.19 (2009-01-05) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1474 Lines: 33 * Anthony Liguori (anthony@codemonkey.ws) wrote: > On 12/22/2009 06:02 PM, Chris Wright wrote: >> * Anthony Liguori (anthony@codemonkey.ws) wrote: >>> The >>> virtio-net setup probably made extensive use of pinning and other tricks >>> to make things faster than a normal user would see them. It ends up >>> creating a perfect combination of batching which is pretty much just >>> cooking the mitigation schemes to do extremely well for one benchmark. >> >> Just pinning, the rest is stock virtio features like mergeable rx buffers, >> GRO, GSO (tx mitigation is actually disabled). > > Technically, tx mitigation isn't disabled. The heuristic is changed > such that instead of relying on a fixed timer, tx notification is > disabled until you can switch to another thread and process packets. > > The effect is that depending on time slice length and system load, you > adaptively enable tx mitigation. It's heavily dependent on the > particulars of the system and the overall load. > > For instance, this mitigation scheme looks great at high throughputs but > looks very bad at mid-to-low throughputs compared to timer based > mitigation (at least, when comparing CPU cost). Yep, you're right. thanks, -chris -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/