From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752066AbaIGKSu (ORCPT ); Sun, 7 Sep 2014 06:18:50 -0400 Received: from mail-we0-f170.google.com ([74.125.82.170]:50427 "EHLO mail-we0-f170.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750971AbaIGKSt (ORCPT ); Sun, 7 Sep 2014 06:18:49 -0400 Message-ID: <540C3101.40701@redhat.com> Date: Sun, 07 Sep 2014 12:18:41 +0200 From: Paolo Bonzini User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.0 MIME-Version: 1.0 To: Christoph Hellwig , Rusty Russell , "Michael S. Tsirkin" CC: Jens Axboe , linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org Subject: Re: [PATCH] virtio_blk: merge S/G list entries by default References: <1410044994-14943-1-git-send-email-hch@lst.de> In-Reply-To: <1410044994-14943-1-git-send-email-hch@lst.de> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Il 07/09/2014 01:09, Christoph Hellwig ha scritto: > Most virtio setups have a fairly limited number of ring entries available. Are you disabling indirect descriptors? With indirect descriptors entry merging doesn't buy you any more space, so perhaps you can key the flag off the availability of VIRTIO_RING_F_INDIRECT_DESC. Paolo > Enable S/G entry merging by default to fit into less of them. This restores > the behavior at time of the virtio-blk blk-mq conversion, which was changed > by commit "block: add queue flag for disabling SG merging" which made the > behavior optional, but didn't update the existing drivers to keep their > previous behavior.