[Top][All Lists]
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Qemu-devel] [PATCH, v3] qemu/xendisk: set maximum number of grants to b
From: |
Jan Beulich |
Subject: |
[Qemu-devel] [PATCH, v3] qemu/xendisk: set maximum number of grants to be used |
Date: |
Thu, 31 May 2012 12:23:46 +0100 |
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.
Change in v2: Double the number requested, as we need to account for
the allocations needing to happen in 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.
Change in v3: introduce MAX_GRANTS(), and add a comment explaining its
definition.
Signed-off-by: Jan Beulich <address@hidden>
--- 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 *
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)
qemu-xendisk-set-max-grants.patch
Description: Text document
- [Qemu-devel] [PATCH, v3] qemu/xendisk: set maximum number of grants to be used,
Jan Beulich <=