From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1031783AbbKECjt (ORCPT ); Wed, 4 Nov 2015 21:39:49 -0500 Received: from userp1040.oracle.com ([156.151.31.81]:44404 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1031593AbbKECjs (ORCPT ); Wed, 4 Nov 2015 21:39:48 -0500 Date: Wed, 4 Nov 2015 21:39:30 -0500 From: Konrad Rzeszutek Wilk To: Bob Liu Cc: xen-devel@lists.xen.org, linux-kernel@vger.kernel.org, roger.pau@citrix.com, felipe.franciosi@citrix.com, axboe@fb.com, avanzini.arianna@gmail.com, rafal.mielniczuk@citrix.com, jonathan.davies@citrix.com, david.vrabel@citrix.com Subject: Re: [PATCH v4 09/10] xen/blkfront: make persistent grants per-queue Message-ID: <20151105023930.GC3949@x230.dumpdata.com> References: <1446438106-20171-1-git-send-email-bob.liu@oracle.com> <1446438106-20171-10-git-send-email-bob.liu@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1446438106-20171-10-git-send-email-bob.liu@oracle.com> User-Agent: Mutt/1.5.23 (2014-03-12) X-Source-IP: userv0022.oracle.com [156.151.31.74] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Nov 02, 2015 at 12:21:45PM +0800, Bob Liu wrote: > Make persistent grants per-queue/ring instead of per-device, so that we can > drop the 'dev_lock' and get better scalability. And what is the performance value for this? How much better scalability do you get with this? .. snip.. > @@ -1010,6 +1002,23 @@ static void blkif_free_ring(struct blkfront_ring_info *rinfo) > } > } > > + /* Remove all persistent grants */ Missing full stop. > + if (!list_empty(&rinfo->grants)) { > + list_for_each_entry_safe(persistent_gnt, n, > + &rinfo->grants, node) { > + list_del(&persistent_gnt->node); > + if (persistent_gnt->gref != GRANT_INVALID_REF) { > + gnttab_end_foreign_access(persistent_gnt->gref, > + 0, 0UL); > + rinfo->persistent_gnts_c--; > + } > + if (info->feature_persistent) > + __free_page(pfn_to_page(persistent_gnt->pfn)); > + kfree(persistent_gnt); > + } > + } > + BUG_ON(rinfo->persistent_gnts_c != 0); > +