[libvirt] [PATCHv4 4/4] qemu aio: enable support

[Eric Blake]

From: Matthias Dahl <mdvirt at designassembly.de>

qemu allows the user to choose what io storage api should be used, either the
default (threads) or native (linux aio) which in the latter case can result in
better performance.

Thanks a lot to Eric Blake and Matthias Bolte for their comments.

Red Hat Bugzilla #591703
Signed-off-by: Eric Blake <eblake at redhat.com>
---

This is so simple, maybe it's worth squashing into 3/4?

 src/qemu/qemu_conf.c |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)

diff --git a/src/qemu/qemu_conf.c b/src/qemu/qemu_conf.c
index 9f84988..87998c1 100644
--- a/src/qemu/qemu_conf.c
+++ b/src/qemu/qemu_conf.c
@@ -2526,6 +2526,11 @@ qemuBuildDriveStr(virDomainDiskDefPtr disk,
         }
     }

+    if (disk->aiomode && (qemuCmdFlags & QEMUD_CMD_FLAG_DRIVE_AIO)) {
+        virBufferVSprintf(&opt, ",aio=%s",
+                          qemuDiskAIOTypeToString(disk->aiomode));
+    }
+
     if (virBufferError(&opt)) {
         virReportOOMError();
         goto error;
-- 
1.7.0.1