Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752305AbbKYR6z (ORCPT ); Wed, 25 Nov 2015 12:58:55 -0500 Received: from aserp1040.oracle.com ([141.146.126.69]:36935 "EHLO aserp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750832AbbKYR6u (ORCPT ); Wed, 25 Nov 2015 12:58:50 -0500 Date: Wed, 25 Nov 2015 12:58:36 -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 v5 08/10] xen/blkback: get the number of hardware queues/rings from blkfront Message-ID: <20151125175836.GC19188@x230.dumpdata.com> References: <1447470739-18136-1-git-send-email-bob.liu@oracle.com> <1447470739-18136-9-git-send-email-bob.liu@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1447470739-18136-9-git-send-email-bob.liu@oracle.com> User-Agent: Mutt/1.5.24 (2015-08-30) X-Source-IP: aserv0022.oracle.com [141.146.126.234] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5099 Lines: 145 On Sat, Nov 14, 2015 at 11:12:17AM +0800, Bob Liu wrote: > Backend advertises "multi-queue-max-queues" to front, also get the negotiated > number from "multi-queue-num-queues" written by blkfront. > > Signed-off-by: Bob Liu > --- > drivers/block/xen-blkback/blkback.c | 12 ++++++++++++ > drivers/block/xen-blkback/common.h | 1 + > drivers/block/xen-blkback/xenbus.c | 34 ++++++++++++++++++++++++++++------ > 3 files changed, 41 insertions(+), 6 deletions(-) > > diff --git a/drivers/block/xen-blkback/blkback.c b/drivers/block/xen-blkback/blkback.c > index fb5bfd4..acedc46 100644 > --- a/drivers/block/xen-blkback/blkback.c > +++ b/drivers/block/xen-blkback/blkback.c > @@ -84,6 +84,15 @@ MODULE_PARM_DESC(max_persistent_grants, > "Maximum number of grants to map persistently"); > > /* > + * Maximum number of rings/queues blkback supports, allow as many queues as there > + * are CPUs if user has not specified a value. > + */ > +unsigned int xenblk_max_queues; > +module_param_named(max_queues, xenblk_max_queues, uint, 0644); > +MODULE_PARM_DESC(max_queues, > + "Maximum number of hardware queues per virtual disk"); Added: unsigned int xenblk_max_queues; module_param_named(max_queues, xenblk_max_queues, uint, 0644); MODULE_PARM_DESC(max_queues, - "Maximum number of hardware queues per virtual disk"); + "Maximum number of hardware queues per virtual disk." \ + "By default it is the number of online CPUs."); /* > + > +/* > * Maximum order of pages to be used for the shared ring between front and > * backend, 4KB page granularity is used. > */ > @@ -1483,6 +1492,9 @@ static int __init xen_blkif_init(void) > xen_blkif_max_ring_order = XENBUS_MAX_RING_GRANT_ORDER; > } > > + if (xenblk_max_queues == 0) > + xenblk_max_queues = num_online_cpus(); > + > rc = xen_blkif_interface_init(); > if (rc) > goto failed_init; > diff --git a/drivers/block/xen-blkback/common.h b/drivers/block/xen-blkback/common.h > index f2386e3..0833dc6 100644 > --- a/drivers/block/xen-blkback/common.h > +++ b/drivers/block/xen-blkback/common.h > @@ -46,6 +46,7 @@ > #include > > extern unsigned int xen_blkif_max_ring_order; > +extern unsigned int xenblk_max_queues; > /* > * This is the maximum number of segments that would be allowed in indirect > * requests. This value will also be passed to the frontend. > diff --git a/drivers/block/xen-blkback/xenbus.c b/drivers/block/xen-blkback/xenbus.c > index 6c6e048..d83b790 100644 > --- a/drivers/block/xen-blkback/xenbus.c > +++ b/drivers/block/xen-blkback/xenbus.c > @@ -181,12 +181,6 @@ static struct xen_blkif *xen_blkif_alloc(domid_t domid) > blkif->st_print = jiffies; > INIT_WORK(&blkif->persistent_purge_work, xen_blkbk_unmap_purged_grants); > > - blkif->nr_rings = 1; > - if (xen_blkif_alloc_rings(blkif)) { > - kmem_cache_free(xen_blkif_cachep, blkif); > - return ERR_PTR(-ENOMEM); > - } > - > return blkif; > } > > @@ -595,6 +589,12 @@ static int xen_blkbk_probe(struct xenbus_device *dev, > goto fail; > } > > + /* Multi-queue: write how many queues are supported by the backend. */ > + err = xenbus_printf(XBT_NIL, dev->nodename, > + "multi-queue-max-queues", "%u", xenblk_max_queues); > + if (err) > + pr_warn("Error writing multi-queue-num-queues\n"); s/num/max/ > + > /* setup back pointer */ > be->blkif->be = be; > > @@ -980,6 +980,7 @@ static int connect_ring(struct backend_info *be) > char *xspath; > size_t xspathsize; > const size_t xenstore_path_ext_size = 11; /* sufficient for "/queue-NNN" */ > + unsigned int requested_num_queues = 0; > > pr_debug("%s %s\n", __func__, dev->otherend); > > @@ -1007,6 +1008,27 @@ static int connect_ring(struct backend_info *be) > be->blkif->vbd.feature_gnt_persistent = pers_grants; > be->blkif->vbd.overflow_max_grants = 0; > > + /* > + * Read the number of hardware queues from frontend. > + */ > + err = xenbus_scanf(XBT_NIL, dev->otherend, "multi-queue-num-queues", > + "%u", &requested_num_queues); > + if (err < 0) { > + requested_num_queues = 1; > + } else { > + if (requested_num_queues > xenblk_max_queues > + || requested_num_queues == 0) { > + /* buggy or malicious guest */ > + xenbus_dev_fatal(dev, err, > + "guest requested %u queues, exceeding the maximum of %u.", > + requested_num_queues, xenblk_max_queues); > + return -1; And made this return -ENOSYS. > + } > + } > + be->blkif->nr_rings = requested_num_queues; > + if (xen_blkif_alloc_rings(be->blkif)) > + return -ENOMEM; > + > pr_info("%s: using %d queues, protocol %d (%s) %s\n", dev->nodename, > be->blkif->nr_rings, be->blkif->blk_protocol, protocol, > pers_grants ? "persistent grants" : ""); > -- > 1.7.10.4 > -- 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/