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| author | Nicolas Saenz Julienne <nsaenzju@redhat.com> | 2022-04-25 09:57:23 +0200 |
|---|---|---|
| committer | Stefan Hajnoczi <stefanha@redhat.com> | 2022-05-09 10:43:23 +0100 |
| commit | 71ad4713cc1d7fca24388b828ef31ae6cb38a31c (patch) | |
| tree | baf49f521c85ffa4551b2cb73083562570b3c857 /qapi | |
| parent | 70ac26b9e5ca8374bb3ef3f30b871726673c9f27 (diff) | |
| download | qemu-71ad4713cc1d7fca24388b828ef31ae6cb38a31c.zip qemu-71ad4713cc1d7fca24388b828ef31ae6cb38a31c.tar.gz qemu-71ad4713cc1d7fca24388b828ef31ae6cb38a31c.tar.bz2 | |
util/event-loop-base: Introduce options to set the thread pool size
The thread pool regulates itself: when idle, it kills threads until
empty, when in demand, it creates new threads until full. This behaviour
doesn't play well with latency sensitive workloads where the price of
creating a new thread is too high. For example, when paired with qemu's
'-mlock', or using safety features like SafeStack, creating a new thread
has been measured take multiple milliseconds.
In order to mitigate this let's introduce a new 'EventLoopBase'
property to set the thread pool size. The threads will be created during
the pool's initialization or upon updating the property's value, remain
available during its lifetime regardless of demand, and destroyed upon
freeing it. A properly characterized workload will then be able to
configure the pool to avoid any latency spikes.
Signed-off-by: Nicolas Saenz Julienne <nsaenzju@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Acked-by: Markus Armbruster <armbru@redhat.com>
Message-id: 20220425075723.20019-4-nsaenzju@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Diffstat (limited to 'qapi')
| -rw-r--r-- | qapi/qom.json | 10 |
1 files changed, 9 insertions, 1 deletions
diff --git a/qapi/qom.json b/qapi/qom.json index 7d4a2ac..6a653c6 100644 --- a/qapi/qom.json +++ b/qapi/qom.json @@ -508,10 +508,18 @@ # 0 means that the engine will use its default. # (default: 0) # +# @thread-pool-min: minimum number of threads reserved in the thread pool +# (default:0) +# +# @thread-pool-max: maximum number of threads the thread pool can contain +# (default:64) +# # Since: 7.1 ## { 'struct': 'EventLoopBaseProperties', - 'data': { '*aio-max-batch': 'int' } } + 'data': { '*aio-max-batch': 'int', + '*thread-pool-min': 'int', + '*thread-pool-max': 'int' } } ## # @IothreadProperties: |