From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752647AbbKBEWp (ORCPT ); Sun, 1 Nov 2015 23:22:45 -0500 Received: from userp1040.oracle.com ([156.151.31.81]:22459 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752404AbbKBEWl (ORCPT ); Sun, 1 Nov 2015 23:22:41 -0500 From: Bob Liu To: xen-devel@lists.xen.org Cc: linux-kernel@vger.kernel.org, roger.pau@citrix.com, konrad.wilk@oracle.com, felipe.franciosi@citrix.com, axboe@fb.com, avanzini.arianna@gmail.com, rafal.mielniczuk@citrix.com, jonathan.davies@citrix.com, david.vrabel@citrix.com, Bob Liu Subject: [PATCH v4 08/10] xen/blkback: get the number of hardware queues/rings from blkfront Date: Mon, 2 Nov 2015 12:21:44 +0800 Message-Id: <1446438106-20171-9-git-send-email-bob.liu@oracle.com> X-Mailer: git-send-email 1.7.10.4 In-Reply-To: <1446438106-20171-1-git-send-email-bob.liu@oracle.com> References: <1446438106-20171-1-git-send-email-bob.liu@oracle.com> 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 Backend advertises "multi-queue-max-queues" to front, then get the negotiated number from "multi-queue-num-queues" wrote by blkfront. Signed-off-by: Bob Liu --- drivers/block/xen-blkback/blkback.c | 11 +++++++++++ drivers/block/xen-blkback/common.h | 1 + drivers/block/xen-blkback/xenbus.c | 35 +++++++++++++++++++++++++++++------ 3 files changed, 41 insertions(+), 6 deletions(-) diff --git a/drivers/block/xen-blkback/blkback.c b/drivers/block/xen-blkback/blkback.c index eaf7ec0..107cc4a 100644 --- a/drivers/block/xen-blkback/blkback.c +++ b/drivers/block/xen-blkback/blkback.c @@ -83,6 +83,11 @@ module_param_named(max_persistent_grants, xen_blkif_max_pgrants, int, 0644); MODULE_PARM_DESC(max_persistent_grants, "Maximum number of grants to map persistently"); +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 order of pages to be used for the shared ring between front and * backend, 4KB page granularity is used. @@ -1478,6 +1483,12 @@ static int __init xen_blkif_init(void) xen_blkif_max_ring_order = XENBUS_MAX_RING_PAGE_ORDER; } + /* Allow as many queues as there are CPUs if user has not + * specified a value. + */ + 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 4de1326..fb28b91 100644 --- a/drivers/block/xen-blkback/common.h +++ b/drivers/block/xen-blkback/common.h @@ -45,6 +45,7 @@ #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 ac4b458..cafbadd 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) INIT_LIST_HEAD(&blkif->persistent_purge_list); 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; } @@ -606,6 +600,14 @@ 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"); + goto fail; + } + /* setup back pointer */ be->blkif->be = be; @@ -997,6 +999,7 @@ 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); @@ -1024,6 +1027,26 @@ 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; + } + } + be->blkif->nr_rings = requested_num_queues; + if (xen_blkif_alloc_rings(be->blkif)) + return -ENOMEM; + pr_info("nr_rings:%d protocol %d (%s) %s\n", be->blkif->nr_rings, be->blkif->blk_protocol, protocol, pers_grants ? "persistent grants" : ""); -- 1.8.3.1