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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH 3/3] xen/block: add multi-page ring support
On 06/03/2015 01:40 PM, Bob Liu wrote: > Extend xen/block to support multi-page ring, so that more requests can be > issued by using more than one pages as the request ring between blkfront > and backend. > As a result, the performance can get improved significantly. > > We got some impressive improvements on our highend iscsi storage cluster > backend. If using 64 pages as the ring, the IOPS increased about 15 times > for the throughput testing and above doubled for the latency testing. > > The reason was the limit on outstanding requests is 32 if use only one-page > ring, but in our case the iscsi lun was spread across about 100 physical > drives, 32 was really not enough to keep them busy. > > Changes in v2: > - Rebased to 4.0-rc6. > - Document on how multi-page ring feature working to linux io/blkif.h. > > Changes in v3: > - Remove changes to linux io/blkif.h and follow the protocol defined > in io/blkif.h of XEN tree. > - Rebased to 4.1-rc3 > > Changes in v4: > - Turn to use 'ring-page-order' and 'max-ring-page-order'. > - A few comments from Roger. > > Changes in v5: > - Clarify with 4k granularity to comment > - Address more comments from Roger > > Signed-off-by: Bob Liu <bob.liu@xxxxxxxxxx> Also tested the windows PV driver which also works fine when multi-page ring feature was enabled in Linux backend. http://www.xenproject.org/downloads/windows-pv-drivers.html Regards, -Bob > --- > drivers/block/xen-blkback/blkback.c | 13 ++++ > drivers/block/xen-blkback/common.h | 2 + > drivers/block/xen-blkback/xenbus.c | 89 +++++++++++++++++------ > drivers/block/xen-blkfront.c | 135 > +++++++++++++++++++++++++---------- > 4 files changed, 180 insertions(+), 59 deletions(-) > > diff --git a/drivers/block/xen-blkback/blkback.c > b/drivers/block/xen-blkback/blkback.c > index 713fc9f..2126842 100644 > --- a/drivers/block/xen-blkback/blkback.c > +++ b/drivers/block/xen-blkback/blkback.c > @@ -84,6 +84,13 @@ MODULE_PARM_DESC(max_persistent_grants, > "Maximum number of grants to map persistently"); > > /* > + * Maximum order of pages to be used for the shared ring between front and > + * backend, 4KB page granularity is used. > + */ > +unsigned int xen_blkif_max_ring_order = XENBUS_MAX_RING_PAGE_ORDER; > +module_param_named(max_ring_page_order, xen_blkif_max_ring_order, int, > S_IRUGO); > +MODULE_PARM_DESC(max_ring_page_order, "Maximum order of pages to be used for > the shared ring"); > +/* > * The LRU mechanism to clean the lists of persistent grants needs to > * be executed periodically. The time interval between consecutive executions > * of the purge mechanism is set in ms. > @@ -1438,6 +1445,12 @@ static int __init xen_blkif_init(void) > if (!xen_domain()) > return -ENODEV; > > + if (xen_blkif_max_ring_order > XENBUS_MAX_RING_PAGE_ORDER) { > + pr_info("Invalid max_ring_order (%d), will use default max: > %d.\n", > + xen_blkif_max_ring_order, XENBUS_MAX_RING_PAGE_ORDER); > + xen_blkif_max_ring_order = XENBUS_MAX_RING_PAGE_ORDER; > + } > + > 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 043f13b..8ccc49d 100644 > --- a/drivers/block/xen-blkback/common.h > +++ b/drivers/block/xen-blkback/common.h > @@ -44,6 +44,7 @@ > #include <xen/interface/io/blkif.h> > #include <xen/interface/io/protocols.h> > > +extern unsigned int xen_blkif_max_ring_order; > /* > * This is the maximum number of segments that would be allowed in indirect > * requests. This value will also be passed to the frontend. > @@ -320,6 +321,7 @@ struct xen_blkif { > struct work_struct free_work; > /* Thread shutdown wait queue. */ > wait_queue_head_t shutdown_wq; > + unsigned int nr_ring_pages; > }; > > struct seg_buf { > diff --git a/drivers/block/xen-blkback/xenbus.c > b/drivers/block/xen-blkback/xenbus.c > index c212d41..deb3f00 100644 > --- a/drivers/block/xen-blkback/xenbus.c > +++ b/drivers/block/xen-blkback/xenbus.c > @@ -25,6 +25,7 @@ > > /* Enlarge the array size in order to fully show blkback name. */ > #define BLKBACK_NAME_LEN (20) > +#define RINGREF_NAME_LEN (20) > > struct backend_info { > struct xenbus_device *dev; > @@ -156,8 +157,8 @@ static struct xen_blkif *xen_blkif_alloc(domid_t domid) > return blkif; > } > > -static int xen_blkif_map(struct xen_blkif *blkif, grant_ref_t gref, > - unsigned int evtchn) > +static int xen_blkif_map(struct xen_blkif *blkif, grant_ref_t *gref, > + unsigned int nr_grefs, unsigned int evtchn) > { > int err; > > @@ -165,7 +166,7 @@ static int xen_blkif_map(struct xen_blkif *blkif, > grant_ref_t gref, > if (blkif->irq) > return 0; > > - err = xenbus_map_ring_valloc(blkif->be->dev, &gref, 1, > + err = xenbus_map_ring_valloc(blkif->be->dev, gref, nr_grefs, > &blkif->blk_ring); > if (err < 0) > return err; > @@ -175,21 +176,21 @@ static int xen_blkif_map(struct xen_blkif *blkif, > grant_ref_t gref, > { > struct blkif_sring *sring; > sring = (struct blkif_sring *)blkif->blk_ring; > - BACK_RING_INIT(&blkif->blk_rings.native, sring, PAGE_SIZE); > + BACK_RING_INIT(&blkif->blk_rings.native, sring, PAGE_SIZE * > nr_grefs); > break; > } > case BLKIF_PROTOCOL_X86_32: > { > struct blkif_x86_32_sring *sring_x86_32; > sring_x86_32 = (struct blkif_x86_32_sring *)blkif->blk_ring; > - BACK_RING_INIT(&blkif->blk_rings.x86_32, sring_x86_32, > PAGE_SIZE); > + BACK_RING_INIT(&blkif->blk_rings.x86_32, sring_x86_32, > PAGE_SIZE * nr_grefs); > break; > } > case BLKIF_PROTOCOL_X86_64: > { > struct blkif_x86_64_sring *sring_x86_64; > sring_x86_64 = (struct blkif_x86_64_sring *)blkif->blk_ring; > - BACK_RING_INIT(&blkif->blk_rings.x86_64, sring_x86_64, > PAGE_SIZE); > + BACK_RING_INIT(&blkif->blk_rings.x86_64, sring_x86_64, > PAGE_SIZE * nr_grefs); > break; > } > default: > @@ -270,7 +271,7 @@ static void xen_blkif_free(struct xen_blkif *blkif) > i++; > } > > - WARN_ON(i != XEN_BLKIF_REQS_PER_PAGE); > + WARN_ON(i != (XEN_BLKIF_REQS_PER_PAGE * blkif->nr_ring_pages)); > > kmem_cache_free(xen_blkif_cachep, blkif); > } > @@ -555,6 +556,11 @@ static int xen_blkbk_probe(struct xenbus_device *dev, > if (err) > goto fail; > > + err = xenbus_printf(XBT_NIL, dev->nodename, "max-ring-page-order", "%u", > + xen_blkif_max_ring_order); > + if (err) > + pr_warn("%s write out 'max-ring-page-order' failed\n", > __func__); > + > err = xenbus_switch_state(dev, XenbusStateInitWait); > if (err) > goto fail; > @@ -818,8 +824,8 @@ again: > static int connect_ring(struct backend_info *be) > { > struct xenbus_device *dev = be->dev; > - unsigned long ring_ref; > - unsigned int evtchn; > + unsigned int ring_ref[XENBUS_MAX_RING_PAGES]; > + unsigned int evtchn, nr_grefs, ring_page_order; > unsigned int pers_grants; > char protocol[64] = ""; > struct pending_req *req, *n; > @@ -827,14 +833,57 @@ static int connect_ring(struct backend_info *be) > > pr_debug("%s %s\n", __func__, dev->otherend); > > - err = xenbus_gather(XBT_NIL, dev->otherend, "ring-ref", "%lu", > - &ring_ref, "event-channel", "%u", &evtchn, NULL); > - if (err) { > - xenbus_dev_fatal(dev, err, > - "reading %s/ring-ref and event-channel", > + err = xenbus_scanf(XBT_NIL, dev->otherend, "event-channel", "%u", > + &evtchn); > + if (err != 1) { > + err = -EINVAL; > + xenbus_dev_fatal(dev, err, "reading %s/event-channel", > dev->otherend); > return err; > } > + pr_info("event-channel %u\n", evtchn); > + > + err = xenbus_scanf(XBT_NIL, dev->otherend, "ring-page-order", "%u", > + &ring_page_order); > + if (err != 1) { > + err = xenbus_scanf(XBT_NIL, dev->otherend, "ring-ref", > + "%u", &ring_ref[0]); > + if (err != 1) { > + err = -EINVAL; > + xenbus_dev_fatal(dev, err, "reading %s/ring-ref", > + dev->otherend); > + return err; > + } > + nr_grefs = 1; > + pr_info("%s:using single page: ring-ref %d\n", dev->otherend, > + ring_ref[0]); > + } else { > + unsigned int i; > + > + if (ring_page_order > xen_blkif_max_ring_order) { > + err = -EINVAL; > + xenbus_dev_fatal(dev, err, "%s/request %d ring page > order exceed max:%d", > + dev->otherend, ring_page_order, > + xen_blkif_max_ring_order); > + return err; > + } > + > + nr_grefs = 1 << ring_page_order; > + for (i = 0; i < nr_grefs; i++) { > + char ring_ref_name[RINGREF_NAME_LEN]; > + > + snprintf(ring_ref_name, RINGREF_NAME_LEN, "ring-ref%u", > i); > + err = xenbus_scanf(XBT_NIL, dev->otherend, > ring_ref_name, > + "%u", &ring_ref[i]); > + if (err != 1) { > + err = -EINVAL; > + xenbus_dev_fatal(dev, err, "reading %s/%s", > + dev->otherend, ring_ref_name); > + return err; > + } > + pr_info("ring-ref%u: %u\n", i, ring_ref[i]); > + } > + } > > be->blkif->blk_protocol = BLKIF_PROTOCOL_DEFAULT; > err = xenbus_gather(XBT_NIL, dev->otherend, "protocol", > @@ -859,12 +908,13 @@ static int connect_ring(struct backend_info *be) > > be->blkif->vbd.feature_gnt_persistent = pers_grants; > be->blkif->vbd.overflow_max_grants = 0; > + be->blkif->nr_ring_pages = nr_grefs; > > - pr_info("ring-ref %ld, event-channel %d, protocol %d (%s) %s\n", > - ring_ref, evtchn, be->blkif->blk_protocol, protocol, > + pr_info("ring-pages:%d, event-channel %d, protocol %d (%s) %s\n", > + nr_grefs, evtchn, be->blkif->blk_protocol, protocol, > pers_grants ? "persistent grants" : ""); > > - for (i = 0; i < XEN_BLKIF_REQS_PER_PAGE; i++) { > + for (i = 0; i < nr_grefs * XEN_BLKIF_REQS_PER_PAGE; i++) { > req = kzalloc(sizeof(*req), GFP_KERNEL); > if (!req) > goto fail; > @@ -883,10 +933,9 @@ static int connect_ring(struct backend_info *be) > } > > /* Map the shared frame, irq etc. */ > - err = xen_blkif_map(be->blkif, ring_ref, evtchn); > + err = xen_blkif_map(be->blkif, ring_ref, nr_grefs, evtchn); > if (err) { > - xenbus_dev_fatal(dev, err, "mapping ring-ref %lu port %u", > - ring_ref, evtchn); > + xenbus_dev_fatal(dev, err, "mapping ring-ref port %u", evtchn); > return err; > } > > diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c > index 88e23fd..d3c1a95 100644 > --- a/drivers/block/xen-blkfront.c > +++ b/drivers/block/xen-blkfront.c > @@ -98,7 +98,21 @@ static unsigned int xen_blkif_max_segments = 32; > module_param_named(max, xen_blkif_max_segments, int, S_IRUGO); > MODULE_PARM_DESC(max, "Maximum amount of segments in indirect requests > (default is 32)"); > > -#define BLK_RING_SIZE __CONST_RING_SIZE(blkif, PAGE_SIZE) > +/* > + * Maximum order of pages to be used for the shared ring between front and > + * backend, 4KB page granularity is used. > + */ > +static unsigned int xen_blkif_max_ring_order; > +module_param_named(max_ring_page_order, xen_blkif_max_ring_order, int, > S_IRUGO); > +MODULE_PARM_DESC(max_ring_page_order, "Maximum order of pages to be used for > the shared ring"); > + > +#define BLK_RING_SIZE(info) __CONST_RING_SIZE(blkif, PAGE_SIZE * > (info)->nr_ring_pages) > +#define BLK_MAX_RING_SIZE __CONST_RING_SIZE(blkif, PAGE_SIZE * > XENBUS_MAX_RING_PAGES) > +/* > + * ring-ref%i i=(-1UL) would take 11 characters + 'ring-ref' is 8, so 19 > + * characters are enough. Define to 20 to keep consist with backend. > + */ > +#define RINGREF_NAME_LEN (20) > > /* > * We have one of these per vbd, whether ide, scsi or 'other'. They > @@ -114,13 +128,14 @@ struct blkfront_info > int vdevice; > blkif_vdev_t handle; > enum blkif_state connected; > - int ring_ref; > + int ring_ref[XENBUS_MAX_RING_PAGES]; > + unsigned int nr_ring_pages; > struct blkif_front_ring ring; > unsigned int evtchn, irq; > struct request_queue *rq; > struct work_struct work; > struct gnttab_free_callback callback; > - struct blk_shadow shadow[BLK_RING_SIZE]; > + struct blk_shadow shadow[BLK_MAX_RING_SIZE]; > struct list_head grants; > struct list_head indirect_pages; > unsigned int persistent_gnts_c; > @@ -139,8 +154,6 @@ static unsigned int nr_minors; > static unsigned long *minors; > static DEFINE_SPINLOCK(minor_lock); > > -#define MAXIMUM_OUTSTANDING_BLOCK_REQS \ > - (BLKIF_MAX_SEGMENTS_PER_REQUEST * BLK_RING_SIZE) > #define GRANT_INVALID_REF 0 > > #define PARTS_PER_DISK 16 > @@ -170,7 +183,7 @@ static int blkfront_setup_indirect(struct blkfront_info > *info); > static int get_id_from_freelist(struct blkfront_info *info) > { > unsigned long free = info->shadow_free; > - BUG_ON(free >= BLK_RING_SIZE); > + BUG_ON(free >= BLK_RING_SIZE(info)); > info->shadow_free = info->shadow[free].req.u.rw.id; > info->shadow[free].req.u.rw.id = 0x0fffffee; /* debug */ > return free; > @@ -983,7 +996,7 @@ static void blkif_free(struct blkfront_info *info, int > suspend) > } > } > > - for (i = 0; i < BLK_RING_SIZE; i++) { > + for (i = 0; i < BLK_RING_SIZE(info); i++) { > /* > * Clear persistent grants present in requests already > * on the shared ring > @@ -1033,12 +1046,15 @@ free_shadow: > flush_work(&info->work); > > /* Free resources associated with old device channel. */ > - if (info->ring_ref != GRANT_INVALID_REF) { > - gnttab_end_foreign_access(info->ring_ref, 0, > - (unsigned long)info->ring.sring); > - info->ring_ref = GRANT_INVALID_REF; > - info->ring.sring = NULL; > + for (i = 0; i < info->nr_ring_pages; i++) { > + if (info->ring_ref[i] != GRANT_INVALID_REF) { > + gnttab_end_foreign_access(info->ring_ref[i], 0, 0); > + info->ring_ref[i] = GRANT_INVALID_REF; > + } > } > + free_pages((unsigned long)info->ring.sring, > get_order(info->nr_ring_pages * PAGE_SIZE)); > + info->ring.sring = NULL; > + > if (info->irq) > unbind_from_irqhandler(info->irq, info); > info->evtchn = info->irq = 0; > @@ -1157,7 +1173,7 @@ static irqreturn_t blkif_interrupt(int irq, void > *dev_id) > * never have given to it (we stamp it up to BLK_RING_SIZE - > * look in get_id_from_freelist. > */ > - if (id >= BLK_RING_SIZE) { > + if (id >= BLK_RING_SIZE(info)) { > WARN(1, "%s: response to %s has incorrect id (%ld)\n", > info->gd->disk_name, op_name(bret->operation), id); > /* We can't safely get the 'struct request' as > @@ -1245,26 +1261,30 @@ static int setup_blkring(struct xenbus_device *dev, > struct blkfront_info *info) > { > struct blkif_sring *sring; > - grant_ref_t gref; > - int err; > + int err, i; > + unsigned long ring_size = info->nr_ring_pages * PAGE_SIZE; > + grant_ref_t gref[XENBUS_MAX_RING_PAGES]; > > - info->ring_ref = GRANT_INVALID_REF; > + for (i = 0; i < info->nr_ring_pages; i++) > + info->ring_ref[i] = GRANT_INVALID_REF; > > - sring = (struct blkif_sring *)__get_free_page(GFP_NOIO | __GFP_HIGH); > + sring = (struct blkif_sring *)__get_free_pages(GFP_NOIO | __GFP_HIGH, > + get_order(ring_size)); > if (!sring) { > xenbus_dev_fatal(dev, -ENOMEM, "allocating shared ring"); > return -ENOMEM; > } > SHARED_RING_INIT(sring); > - FRONT_RING_INIT(&info->ring, sring, PAGE_SIZE); > + FRONT_RING_INIT(&info->ring, sring, ring_size); > > - err = xenbus_grant_ring(dev, info->ring.sring, 1, &gref); > + err = xenbus_grant_ring(dev, info->ring.sring, info->nr_ring_pages, > gref); > if (err < 0) { > - free_page((unsigned long)sring); > + free_pages((unsigned long)sring, get_order(ring_size)); > info->ring.sring = NULL; > goto fail; > } > - info->ring_ref = gref; > + for (i = 0; i < info->nr_ring_pages; i++) > + info->ring_ref[i] = gref[i]; > > err = xenbus_alloc_evtchn(dev, &info->evtchn); > if (err) > @@ -1292,7 +1312,18 @@ static int talk_to_blkback(struct xenbus_device *dev, > { > const char *message = NULL; > struct xenbus_transaction xbt; > - int err; > + int err, i; > + unsigned int max_page_order = 0; > + unsigned int ring_page_order = 0; > + > + err = xenbus_scanf(XBT_NIL, info->xbdev->otherend, > + "max-ring-page-order", "%u", &max_page_order); > + if (err != 1) > + info->nr_ring_pages = 1; > + else { > + ring_page_order = min(xen_blkif_max_ring_order, max_page_order); > + info->nr_ring_pages = 1 << ring_page_order; > + } > > /* Create shared ring, alloc event channel. */ > err = setup_blkring(dev, info); > @@ -1306,11 +1337,32 @@ again: > goto destroy_blkring; > } > > - err = xenbus_printf(xbt, dev->nodename, > - "ring-ref", "%u", info->ring_ref); > - if (err) { > - message = "writing ring-ref"; > - goto abort_transaction; > + if (info->nr_ring_pages == 1) { > + err = xenbus_printf(xbt, dev->nodename, > + "ring-ref", "%u", info->ring_ref[0]); > + if (err) { > + message = "writing ring-ref"; > + goto abort_transaction; > + } > + } else { > + err = xenbus_printf(xbt, dev->nodename, > + "ring-page-order", "%u", ring_page_order); > + if (err) { > + message = "writing ring-page-order"; > + goto abort_transaction; > + } > + > + for (i = 0; i < info->nr_ring_pages; i++) { > + char ring_ref_name[RINGREF_NAME_LEN]; > + > + snprintf(ring_ref_name, RINGREF_NAME_LEN, "ring-ref%u", > i); > + err = xenbus_printf(xbt, dev->nodename, ring_ref_name, > + "%u", info->ring_ref[i]); > + if (err) { > + message = "writing ring-ref"; > + goto abort_transaction; > + } > + } > } > err = xenbus_printf(xbt, dev->nodename, > "event-channel", "%u", info->evtchn); > @@ -1338,6 +1390,9 @@ again: > goto destroy_blkring; > } > > + for (i = 0; i < BLK_RING_SIZE(info); i++) > + info->shadow[i].req.u.rw.id = i+1; > + info->shadow[BLK_RING_SIZE(info)-1].req.u.rw.id = 0x0fffffff; > xenbus_switch_state(dev, XenbusStateInitialised); > > return 0; > @@ -1361,7 +1416,7 @@ again: > static int blkfront_probe(struct xenbus_device *dev, > const struct xenbus_device_id *id) > { > - int err, vdevice, i; > + int err, vdevice; > struct blkfront_info *info; > > /* FIXME: Use dynamic device id if this is not set. */ > @@ -1422,10 +1477,6 @@ static int blkfront_probe(struct xenbus_device *dev, > info->connected = BLKIF_STATE_DISCONNECTED; > INIT_WORK(&info->work, blkif_restart_queue); > > - for (i = 0; i < BLK_RING_SIZE; i++) > - info->shadow[i].req.u.rw.id = i+1; > - info->shadow[BLK_RING_SIZE-1].req.u.rw.id = 0x0fffffff; > - > /* Front end dir is a number, which is used as the id. */ > info->handle = simple_strtoul(strrchr(dev->nodename, '/')+1, NULL, 0); > dev_set_drvdata(&dev->dev, info); > @@ -1469,10 +1520,10 @@ static int blkif_recover(struct blkfront_info *info) > > /* Stage 2: Set up free list. */ > memset(&info->shadow, 0, sizeof(info->shadow)); > - for (i = 0; i < BLK_RING_SIZE; i++) > + for (i = 0; i < BLK_RING_SIZE(info); i++) > info->shadow[i].req.u.rw.id = i+1; > info->shadow_free = info->ring.req_prod_pvt; > - info->shadow[BLK_RING_SIZE-1].req.u.rw.id = 0x0fffffff; > + info->shadow[BLK_RING_SIZE(info)-1].req.u.rw.id = 0x0fffffff; > > rc = blkfront_setup_indirect(info); > if (rc) { > @@ -1484,7 +1535,7 @@ static int blkif_recover(struct blkfront_info *info) > blk_queue_max_segments(info->rq, segs); > bio_list_init(&bio_list); > INIT_LIST_HEAD(&requests); > - for (i = 0; i < BLK_RING_SIZE; i++) { > + for (i = 0; i < BLK_RING_SIZE(info); i++) { > /* Not in use? */ > if (!copy[i].request) > continue; > @@ -1690,7 +1741,7 @@ static int blkfront_setup_indirect(struct blkfront_info > *info) > segs = info->max_indirect_segments; > } > > - err = fill_grant_buffer(info, (segs + INDIRECT_GREFS(segs)) * > BLK_RING_SIZE); > + err = fill_grant_buffer(info, (segs + INDIRECT_GREFS(segs)) * > BLK_RING_SIZE(info)); > if (err) > goto out_of_memory; > > @@ -1700,7 +1751,7 @@ static int blkfront_setup_indirect(struct blkfront_info > *info) > * grants, we need to allocate a set of pages that can be > * used for mapping indirect grefs > */ > - int num = INDIRECT_GREFS(segs) * BLK_RING_SIZE; > + int num = INDIRECT_GREFS(segs) * BLK_RING_SIZE(info); > > BUG_ON(!list_empty(&info->indirect_pages)); > for (i = 0; i < num; i++) { > @@ -1711,7 +1762,7 @@ static int blkfront_setup_indirect(struct blkfront_info > *info) > } > } > > - for (i = 0; i < BLK_RING_SIZE; i++) { > + for (i = 0; i < BLK_RING_SIZE(info); i++) { > info->shadow[i].grants_used = kzalloc( > sizeof(info->shadow[i].grants_used[0]) * segs, > GFP_NOIO); > @@ -1733,7 +1784,7 @@ static int blkfront_setup_indirect(struct blkfront_info > *info) > return 0; > > out_of_memory: > - for (i = 0; i < BLK_RING_SIZE; i++) { > + for (i = 0; i < BLK_RING_SIZE(info); i++) { > kfree(info->shadow[i].grants_used); > info->shadow[i].grants_used = NULL; > kfree(info->shadow[i].sg); > @@ -2089,6 +2140,12 @@ static int __init xlblk_init(void) > if (!xen_domain()) > return -ENODEV; > > + if (xen_blkif_max_ring_order > XENBUS_MAX_RING_PAGE_ORDER) { > + pr_info("Invalid max_ring_order (%d), will use default max: > %d.\n", > + xen_blkif_max_ring_order, XENBUS_MAX_RING_PAGE_ORDER); > + xen_blkif_max_ring_order = 0; > + } > + > if (!xen_has_pv_disk_devices()) > return -ENODEV; > > _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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