From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753127AbaETLlX (ORCPT ); Tue, 20 May 2014 07:41:23 -0400 Received: from mx1.redhat.com ([209.132.183.28]:27183 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751801AbaETLlV (ORCPT ); Tue, 20 May 2014 07:41:21 -0400 From: Vitaly Kuznetsov To: Roger Pau =?utf-8?Q?Monn=C3=A9?= Cc: Konrad Rzeszutek Wilk , axboe@kernel.dk, felipe.franciosi@citrix.com, gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org, jerry.snitselaar@oracle.com, xen-devel@lists.xenproject.org Subject: Re: [Xen-devel] Backport request to stable of two performance related fixes for xen-blkfront (3.13 fixes to earlier trees) References: <20140514191122.GA7659@phenom.dumpdata.com> <8738g44wxp.fsf@vitty.brq.redhat.com> <87ppj8zsfb.fsf@vitty.brq.redhat.com> <537B2F2C.4080905@citrix.com> Date: Tue, 20 May 2014 13:41:10 +0200 In-Reply-To: <537B2F2C.4080905@citrix.com> ("Roger Pau \=\?utf-8\?Q\?Monn\?\= \=\?utf-8\?Q\?\=C3\=A9\=22's\?\= message of "Tue, 20 May 2014 12:32:12 +0200") Message-ID: <87lhtwznhl.fsf@vitty.brq.redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.3 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Roger Pau Monné writes: > On 20/05/14 11:54, Vitaly Kuznetsov wrote: >> Vitaly Kuznetsov writes: >> >>> 1) ramdisks (/dev/ram*) (persistent grants and indirect descriptors >>> disabled) >> >> sorry, there was a typo. persistent grants and indirect descriptors are >> enabled with ramdisks, otherwise such testing won't make any sense. > > I'm not sure how is that possible, from your description I get that you > are using 3.11 on the Dom0, which means blkback has support for > persistent grants and indirect descriptors, but the guest is RHEL7, > that's using the 3.10 kernel AFAICT, and this kernel only has persistent > grants implemented. RHEL7 kernel is mostly merged with 3.11 in its Xen part, we have indirect descriptors backported. Actually I tried my tests with upstream (Fedora) kernel and results were similar. I can try comparing e.g. 3.11.10 with 3.12.0 and provide exact measurements. -- Vitaly