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authorJan Beulich <JBeulich@suse.com>2012-06-11 09:52:27 +0000
committerMichael Roth <mdroth@linux.vnet.ibm.com>2012-06-25 09:00:42 -0500
commitc9c2479289fd1faf4a1a40db54cc255fbf03af21 (patch)
tree29b1756f47558ba263f6bf9750d6b5b9359af301
parentbuild: install qmp-commands.txt (diff)
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qemu/xendisk: set maximum number of grants to be used
Legacy (non-pvops) gntdev drivers may require this to be done when the number of grants intended to be used simultaneously exceeds a certain driver specific default limit. Signed-off-by: Jan Beulich <jbeulich@suse.com> Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com> (cherry picked from commit 64c27e5b1fdb6d94bdc0bda3b1869d7383a35c65) Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
-rw-r--r--hw/xen_disk.c14
1 files changed, 14 insertions, 0 deletions
diff --git a/hw/xen_disk.c b/hw/xen_disk.c
index 07594bc0c..de7e8a4a5 100644
--- a/hw/xen_disk.c
+++ b/hw/xen_disk.c
@@ -537,6 +537,15 @@ static void blk_bh(void *opaque)
blk_handle_requests(blkdev);
}
+/*
+ * We need to account for the grant allocations requiring contiguous
+ * chunks; the worst case number would be
+ * max_req * max_seg + (max_req - 1) * (max_seg - 1) + 1,
+ * but in order to keep things simple just use
+ * 2 * max_req * max_seg.
+ */
+#define MAX_GRANTS(max_req, max_seg) (2 * (max_req) * (max_seg))
+
static void blk_alloc(struct XenDevice *xendev)
{
struct XenBlkDev *blkdev = container_of(xendev, struct XenBlkDev, xendev);
@@ -548,6 +557,11 @@ static void blk_alloc(struct XenDevice *xendev)
if (xen_mode != XEN_EMULATE) {
batch_maps = 1;
}
+ if (xc_gnttab_set_max_grants(xendev->gnttabdev,
+ MAX_GRANTS(max_requests, BLKIF_MAX_SEGMENTS_PER_REQUEST)) < 0) {
+ xen_be_printf(xendev, 0, "xc_gnttab_set_max_grants failed: %s\n",
+ strerror(errno));
+ }
}
static int blk_init(struct XenDevice *xendev)