improve DMA transfers by increasing the size of DMA buffers.

Signed-off-by: Samuel Thibault <samuel.thibault@eu.citrix.com>
Cross-ported from xen-unstable f4a92f0db20fda98a633c149e3396c005a759a77

diff --git a/hw/scsi-disk.c b/hw/scsi-disk.c
index 91fcc70a04dd9babf9db869aab831c66529fd831..3f781666380f8d598e09feaa34b93366682e1c85 100644 (file)
--- a/hw/scsi-disk.c
+++ b/hw/scsi-disk.c
@@ -34,7 +34,12 @@ do { fprintf(stderr, "scsi-disk: " fmt , ##args); } while (0)
 #define SENSE_HARDWARE_ERROR  4
 #define SENSE_ILLEGAL_REQUEST 5
 
-#define SCSI_DMA_BUF_SIZE    65536
+#ifdef CONFIG_STUBDOM
+#include <xen/io/blkif.h>
+#define SCSI_DMA_BUF_SIZE    (BLKIF_MAX_SEGMENTS_PER_REQUEST * TARGET_PAGE_SIZE)
+#else
+#define SCSI_DMA_BUF_SIZE    131072
+#endif
 
 typedef struct SCSIRequest {
     SCSIDeviceState *dev;