[Xen-devel] [PATCH 1/1] libxl: use qemu-xen with PV guests by default

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

qemu-xen offers better disk performances than qemu-xen-traditional
because it supports Linux native AIO: use it for PV guests if it is
available.

Changes in v2:
- check for the existence of the qemu-xen binary before setting qemu-xen
as the default device model for PV guests.

Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
---
 tools/libxl/libxl_create.c |   29 ++++++++++++++++++++++++-----
 1 files changed, 24 insertions(+), 5 deletions(-)

diff --git a/tools/libxl/libxl_create.c b/tools/libxl/libxl_create.c
index e63c7bd..b71524e 100644
--- a/tools/libxl/libxl_create.c
+++ b/tools/libxl/libxl_create.c
@@ -71,9 +71,30 @@ int libxl__domain_build_info_setdefault(libxl__gc *gc,
         b_info->type != LIBXL_DOMAIN_TYPE_PV)
         return ERROR_INVAL;
 
-    if (!b_info->device_model_version)
-        b_info->device_model_version =
-            LIBXL_DEVICE_MODEL_VERSION_QEMU_XEN_TRADITIONAL;
+    libxl_defbool_setdefault(&b_info->device_model_stubdomain, false);
+
+    if (!b_info->device_model_version) {
+        if (b_info->type == LIBXL_DOMAIN_TYPE_HVM)
+            b_info->device_model_version =
+                LIBXL_DEVICE_MODEL_VERSION_QEMU_XEN_TRADITIONAL;
+        else {
+            const char *dm;
+            struct stat buf;
+            int rc;
+
+            b_info->device_model_version =
+                LIBXL_DEVICE_MODEL_VERSION_QEMU_XEN;
+            dm = libxl__domain_device_model(gc, b_info);
+            rc = stat(dm, &buf);
+            /* qemu-xen unavailable, use qemu-xen-traditional */
+            if (rc != 0) {
+                LIBXL__LOG(CTX, XTL_VERBOSE, "setting device model to "
+                        "qemu-xen-traditional because qemu-xen is 
unavailable");
+                b_info->device_model_version =
+                    LIBXL_DEVICE_MODEL_VERSION_QEMU_XEN_TRADITIONAL;
+            }
+        }
+    }
 
     if (b_info->type == LIBXL_DOMAIN_TYPE_HVM) {
         if (!b_info->u.hvm.bios)
@@ -99,8 +120,6 @@ int libxl__domain_build_info_setdefault(libxl__gc *gc,
         }
     }
 
-    libxl_defbool_setdefault(&b_info->device_model_stubdomain, false);
-
     if (b_info->type == LIBXL_DOMAIN_TYPE_HVM &&
         b_info->device_model_version !=
             LIBXL_DEVICE_MODEL_VERSION_QEMU_XEN_TRADITIONAL &&
-- 
1.7.2.5


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel