On Thu, Sep 01, 2011 at 02:42:56PM -0600, Jim Fehlig wrote:
> From: Jim Fehlig <jfehlig@xxxxxxxxxx>
>
> The qemu migration speed default is 32MiB/s as defined in migration.c
>
> /* Migration speed throttling */
> static int64_t max_throttle = (32 << 20);
>
> There's no need to throttle migration when targeting a file, so set migration
> speed to unlimited prior to migration, and restore to libvirt default value
> after migration.
>
> Default units is MB for migrate_set_speed monitor command, so
> (INT64_MAX / (1024 * 1024)) is used for unlimited migration speed.
>
> Tested with both json and text monitors.
> ---
> src/qemu/qemu_migration.c | 17 +++++++++++++++++
> 1 files changed, 17 insertions(+), 0 deletions(-)
>
> diff --git a/src/qemu/qemu_migration.c b/src/qemu/qemu_migration.c
> index 38b05a9..ab38579 100644
> --- a/src/qemu/qemu_migration.c
> +++ b/src/qemu/qemu_migration.c
> @@ -2700,6 +2700,16 @@ qemuMigrationToFile(struct qemud_driver *driver, virDomainObjPtr vm,
> bool restoreLabel = false;
> virCommandPtr cmd = NULL;
> int pipeFD[2] = { -1, -1 };
> + unsigned long saveMigBandwidth = priv->migMaxBandwidth;
> +
> + /* Increase migration bandwidth to unlimited since target is a file.
> + * Failure to change migration speed is not fatal. */
> + if (qemuDomainObjEnterMonitorAsync(driver, vm, asyncJob) == 0) {
> + qemuMonitorSetMigrationSpeed(priv->mon,
> + QEMU_DOMAIN_FILE_MIG_BANDWIDTH_MAX);
> + priv->migMaxBandwidth = QEMU_DOMAIN_FILE_MIG_BANDWIDTH_MAX;
> + qemuDomainObjExitMonitorWithDriver(driver, vm);
> + }
>
> if (qemuCapsGet(priv->qemuCaps, QEMU_CAPS_MIGRATE_QEMU_FD) &&
> (!compressor || pipe(pipeFD) == 0)) {
> @@ -2808,6 +2818,13 @@ qemuMigrationToFile(struct qemud_driver *driver, virDomainObjPtr vm,
> ret = 0;
>
> cleanup:
> + /* Restore max migration bandwidth */
> + if (qemuDomainObjEnterMonitorAsync(driver, vm, asyncJob) == 0) {
> + qemuMonitorSetMigrationSpeed(priv->mon, saveMigBandwidth);
> + priv->migMaxBandwidth = saveMigBandwidth;
> + qemuDomainObjExitMonitorWithDriver(driver, vm);
> + }
> +
> VIR_FORCE_CLOSE(pipeFD[0]);
> VIR_FORCE_CLOSE(pipeFD[1]);
> virCommandFree(cmd);
ACK, makes sense, my only worry would be handling of errors, for
example if for some reason qemuMonitorSetMigrationSpeed() generate
a failure, we ignore it, which may make sense for some kind of errors
(like failure to understand the command) but I'm worried of more
complex scenarios. Since I don't have one handy, I'm giving the ACK :-)
Daniel
--
Daniel Veillard | libxml Gnome XML XSLT toolkit http://xmlsoft.org/
daniel@xxxxxxxxxxxx | Rpmfind RPM search engine http://rpmfind.net/
http://veillard.com/ | virtualization library http://libvirt.org/
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