[libvirt] [PATCH v2 4/4] qemu: Allow use of iothreads for disk definitions

[Martin Kletzander]

On Tue, Aug 26, 2014 at 06:15:49PM -0400, John Ferlan wrote:
>For virtio-blk-pci disks with the disk iothread attribute that are
>running the correct emulator, add the "iothread=iothread#" to the
>-device command line in order to enable iothreads for the disk.
>
>This code will check both the "start" and "hotplug" paths for the capability,
>whether the iothreadsmap has been defined, and whether there's an available
>iothread to be used for the disk.
>
>Signed-off-by: John Ferlan <jferlan at redhat.com>
>---
> src/qemu/qemu_command.c                            | 51 ++++++++++++++++++++++
> src/qemu/qemu_hotplug.c                            |  6 +++
> .../qemuxml2argv-iothreads-disk.args               | 17 ++++++++
> .../qemuxml2argv-iothreads-disk.xml                | 40 +++++++++++++++++
> tests/qemuxml2argvtest.c                           |  2 +
> tests/qemuxml2xmltest.c                            |  1 +
> 6 files changed, 117 insertions(+)
> create mode 100644 tests/qemuxml2argvdata/qemuxml2argv-iothreads-disk.args
> create mode 100644 tests/qemuxml2argvdata/qemuxml2argv-iothreads-disk.xml
>
>diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c
>index ba0b977..763bb74 100644
>--- a/src/qemu/qemu_command.c
>+++ b/src/qemu/qemu_command.c
>@@ -3673,6 +3673,49 @@ qemuBuildDriveStr(virConnectPtr conn,
>     return NULL;
> }
>
>+
>+static bool
>+qemuCheckIothreads(virDomainDefPtr def,
>+                   virQEMUCapsPtr qemuCaps,
>+                   virDomainDiskDefPtr disk)
>+{
>+    bool inuse;
>+
>+    /* Have capability */
>+    if (!virQEMUCapsGet(qemuCaps, QEMU_CAPS_OBJECT_IOTHREAD)) {
>+        virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
>+                       _("IOThreads not supported for this QEMU"));
>+        return false;
>+    }
>+
>+    /* Right "type" of disk" */
>+    if (disk->bus != VIR_DOMAIN_DISK_BUS_VIRTIO &&
>+        disk->info.type != VIR_DOMAIN_DEVICE_ADDRESS_TYPE_PCI) {
>+        virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
>+                       _("IOThreads not available for this disk"));

Sorry to say that, but this is like another extreme, it feels too
generic.  If there are multiple disks, the user might not be sure
which one you mean.  Listing the allowed ones is fine, I'd say
something like "IOThreads only available for virtio pci disk" is
enough.

ACK with that changed.

Martin
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