Re: [PATCH v2 11/15] qemu: Wire up new virDomainSetIOThreadParams parameters
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(a)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