[libvirt] [PATCH 3/3] qemu aio: enable support

[Eric Blake]

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.

Based on a patch originally by Matthias Dahl.

Red Hat Bugzilla #591703
Signed-off-by: Eric Blake <eblake at redhat.com>
---
 src/qemu/qemu_command.c                           |   17 +++++++++++
 tests/qemuxml2argvdata/qemuxml2argv-disk-aio.args |    1 +
 tests/qemuxml2argvdata/qemuxml2argv-disk-aio.xml  |   33 +++++++++++++++++++++
 tests/qemuxml2argvtest.c                          |    2 +
 tests/qemuxml2xmltest.c                           |    1 +
 5 files changed, 54 insertions(+), 0 deletions(-)
 create mode 100644 tests/qemuxml2argvdata/qemuxml2argv-disk-aio.args
 create mode 100644 tests/qemuxml2argvdata/qemuxml2argv-disk-aio.xml

diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c
index fff1f74..c93de0b 100644
--- a/src/qemu/qemu_command.c
+++ b/src/qemu/qemu_command.c
@@ -1328,6 +1328,18 @@ qemuBuildDriveStr(virDomainDiskDefPtr disk,
         }
     }

+    if (disk->iomode) {
+        if (qemuCmdFlags & QEMUD_CMD_FLAG_DRIVE_AIO) {
+            virBufferVSprintf(&opt, ",aio=%s",
+                              virDomainDiskIoTypeToString(disk->iomode));
+        } else {
+            qemuReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+                            _("disk aio mode not supported with this "
+                              "QEMU binary"));
+            goto error;
+        }
+    }
+
     if (virBufferError(&opt)) {
         virReportOOMError();
         goto error;
@@ -4426,6 +4438,11 @@ qemuParseCommandLineDisk(virCapsPtr caps,
         } else if (STREQ(keywords[i], "readonly")) {
             if ((values[i] == NULL) || STREQ(values[i], "on"))
                 def->readonly = 1;
+        } else if (STREQ(keywords[i], "aio")) {
+            if ((def->iomode = virDomainDiskIoTypeFromString(values[i])) < 0) {
+                qemuReportError(VIR_ERR_INTERNAL_ERROR,
+                                _("cannot parse io mode '%s'"), values[i]);
+            }
         }
     }

diff --git a/tests/qemuxml2argvdata/qemuxml2argv-disk-aio.args b/tests/qemuxml2argvdata/qemuxml2argv-disk-aio.args
new file mode 100644
index 0000000..15d2a1b
--- /dev/null
+++ b/tests/qemuxml2argvdata/qemuxml2argv-disk-aio.args
@@ -0,0 +1 @@
+LC_ALL=C PATH=/bin HOME=/home/test USER=test LOGNAME=test /usr/bin/qemu -S -M pc -m 214 -smp 1 -nographic -monitor unix:/tmp/test-monitor,server,nowait -no-acpi -boot c -drive file=/dev/HostVG/QEMUGuest1,if=ide,bus=0,unit=0,format=qcow2,cache=none,aio=native -drive file=/dev/HostVG/QEMUGuest2,if=ide,media=cdrom,bus=1,unit=0,format=raw,aio=threads -net none -serial none -parallel none -usb
diff --git a/tests/qemuxml2argvdata/qemuxml2argv-disk-aio.xml b/tests/qemuxml2argvdata/qemuxml2argv-disk-aio.xml
new file mode 100644
index 0000000..d893736
--- /dev/null
+++ b/tests/qemuxml2argvdata/qemuxml2argv-disk-aio.xml
@@ -0,0 +1,33 @@
+<domain type='qemu'>
+  <name>QEMUGuest1</name>
+  <uuid>c7a5fdbd-edaf-9455-926a-d65c16db1809</uuid>
+  <memory>219200</memory>
+  <currentMemory>219200</currentMemory>
+  <vcpu>1</vcpu>
+  <os>
+    <type arch='i686' machine='pc'>hvm</type>
+    <boot dev='hd'/>
+  </os>
+  <clock offset='utc'/>
+  <on_poweroff>destroy</on_poweroff>
+  <on_reboot>restart</on_reboot>
+  <on_crash>destroy</on_crash>
+  <devices>
+    <emulator>/usr/bin/qemu</emulator>
+    <disk type='block' device='disk'>
+      <driver name='qemu' type='qcow2' cache='none' io='native'/>
+      <source dev='/dev/HostVG/QEMUGuest1'/>
+      <target dev='hda' bus='ide'/>
+      <address type='drive' controller='0' bus='0' unit='0'/>
+    </disk>
+    <disk type='block' device='cdrom'>
+      <driver name='qemu' type='raw' io='threads'/>
+      <source dev='/dev/HostVG/QEMUGuest2'/>
+      <target dev='hdc' bus='ide'/>
+      <readonly/>
+      <address type='drive' controller='0' bus='1' unit='0'/>
+    </disk>
+    <controller type='ide' index='0'/>
+    <memballoon model='virtio'/>
+  </devices>
+</domain>
diff --git a/tests/qemuxml2argvtest.c b/tests/qemuxml2argvtest.c
index d7951df..07f8b60 100644
--- a/tests/qemuxml2argvtest.c
+++ b/tests/qemuxml2argvtest.c
@@ -314,6 +314,8 @@ mymain(int argc, char **argv)
             QEMUD_CMD_FLAG_DEVICE | QEMUD_CMD_FLAG_NODEFCONFIG, false);
     DO_TEST("disk-scsi-device-auto", QEMUD_CMD_FLAG_DRIVE |
             QEMUD_CMD_FLAG_DEVICE | QEMUD_CMD_FLAG_NODEFCONFIG, false);
+    DO_TEST("disk-aio", QEMUD_CMD_FLAG_DRIVE | QEMUD_CMD_FLAG_DRIVE_AIO |
+            QEMUD_CMD_FLAG_DRIVE_CACHE_V2 | QEMUD_CMD_FLAG_DRIVE_FORMAT, false);
     DO_TEST("graphics-vnc", 0, false);

     driver.vncSASL = 1;
diff --git a/tests/qemuxml2xmltest.c b/tests/qemuxml2xmltest.c
index 326a1f1..fd981e8 100644
--- a/tests/qemuxml2xmltest.c
+++ b/tests/qemuxml2xmltest.c
@@ -131,6 +131,7 @@ mymain(int argc, char **argv)
     DO_TEST("clock-utc");
     DO_TEST("clock-localtime");
     DO_TEST("hugepages");
+    DO_TEST("disk-aio");
     DO_TEST("disk-cdrom");
     DO_TEST("disk-floppy");
     DO_TEST("disk-many");
-- 
1.7.3.4