On Tue, Jun 07, 2022 at 17:06:50 +0200, Peter Krempa wrote:
On Tue, Jun 07, 2022 at 14:52:55 +0200, Michal Privoznik wrote:
Introduced in previous commit, QEMU driver needs to be taught how to set VIR_DOMAIN_IOTHREAD_THREAD_POOL_MIN and VIR_DOMAIN_IOTHREAD_THREAD_POOL_MAX parameters on given IOThread. Fortunately, this is fairly trivial to do and since these two parameters are exposed in domain XML too the update of inactive XML can be wired up too.
Signed-off-by: Michal Privoznik <mprivozn@redhat.com> --- src/qemu/qemu_driver.c | 62 +++++++++++++++++++++++++++++++++--- src/qemu/qemu_monitor.h | 4 +++ src/qemu/qemu_monitor_json.c | 2 ++ 3 files changed, 63 insertions(+), 5 deletions(-)
diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c index 0c6645ed89..1770a1882b 100644 --- a/src/qemu/qemu_driver.c +++ b/src/qemu/qemu_driver.c
[...]
diff --git a/src/qemu/qemu_monitor_json.c b/src/qemu/qemu_monitor_json.c index dc05dfd047..e8fe1eceae 100644 --- a/src/qemu/qemu_monitor_json.c +++ b/src/qemu/qemu_monitor_json.c @@ -7431,6 +7431,8 @@ qemuMonitorJSONSetIOThread(qemuMonitor *mon, VIR_IOTHREAD_SET_PROP("poll-max-ns", poll_max_ns); VIR_IOTHREAD_SET_PROP("poll-grow", poll_grow); VIR_IOTHREAD_SET_PROP("poll-shrink", poll_shrink); + VIR_IOTHREAD_SET_PROP("thread-pool-min", thread_pool_min); + VIR_IOTHREAD_SET_PROP("thread-pool-max", thread_pool_max);
+/** + * VIR_DOMAIN_IOTHREAD_THREAD_POOL_MIN: + * + * Sets the lower bound for thread pool size. A value of -1 disables this bound + * leaving hypervisor use its default value. Accepted type is + * VIR_TYPED_PARAM_INT. + * + * Since: 8.5.0 + */ +# define VIR_DOMAIN_IOTHREAD_THREAD_POOL_MIN "thread_pool_min"
I've tried following:
$ virsh iothreadset cd --id 3 --thread-pool-min 123 error: internal error: unable to execute QEMU command 'qom-set': bad thread-pool-min/thread-pool-max values
$ virsh iothreadset cd --id 3 --thread-pool-max 123
$ virsh iothreadset cd --id 3 --thread-pool-min 2
$ virsh iothreadset cd --id 3 --thread-pool-min -1 error: internal error: unable to execute QEMU command 'qom-set': thread-pool-min value must be in range [0, 9223372036854775807]
There are two conclusions: - '-1' value simply doesn't work as documented - we'll need to document that when live-setting 'max' needs to be set first
So the second happens only if you pick a minimum which is greater than the maximum auto-picked by qemu. Also since VIR_IOTHREAD_SET_PROP is a discrete command the following compound operation doesn't work properly: virsh iothreadset cd --id 3 --thread-pool-max 1234 --thread-pool-min 123 error: internal error: unable to execute QEMU command 'qom-set': bad thread-pool-min/thread-pool-max values As it would IMO be a bit too overkill to try to order them properly when changing the size I suggest you ask users to do it sequentially in the docs.