From 64c27e5b1fdb6d94bdc0bda3b1869d7383a35c65 Mon Sep 17 00:00:00 2001 From: Jan Beulich Date: Mon, 11 Jun 2012 09:52:27 +0000 Subject: 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 Signed-off-by: Stefano Stabellini --- hw/xen_disk.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) (limited to 'hw/xen_disk.c') diff --git a/hw/xen_disk.c b/hw/xen_disk.c index 07594bc..de7e8a4 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) -- cgit v1.1