From 1793ad0247cad35db1ebbc04fbea0446c30a27ca Mon Sep 17 00:00:00 2001 From: Stefano Garzarella Date: Wed, 21 Jul 2021 11:42:10 +0200 Subject: iothread: add aio-max-batch parameter The `aio-max-batch` parameter will be propagated to AIO engines and it will be used to control the maximum number of queued requests. When there are in queue a number of requests equal to `aio-max-batch`, the engine invokes the system call to forward the requests to the kernel. This parameter allows us to control the maximum batch size to reduce the latency that requests might accumulate while queued in the AIO engine queue. If `aio-max-batch` is equal to 0 (default value), the AIO engine will use its default maximum batch size value. Signed-off-by: Stefano Garzarella Message-id: 20210721094211.69853-3-sgarzare@redhat.com Signed-off-by: Stefan Hajnoczi --- qemu-options.hx | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) (limited to 'qemu-options.hx') diff --git a/qemu-options.hx b/qemu-options.hx index 0c9ddc0..99ed5ec 100644 --- a/qemu-options.hx +++ b/qemu-options.hx @@ -5301,7 +5301,7 @@ SRST CN=laptop.example.com,O=Example Home,L=London,ST=London,C=GB - ``-object iothread,id=id,poll-max-ns=poll-max-ns,poll-grow=poll-grow,poll-shrink=poll-shrink`` + ``-object iothread,id=id,poll-max-ns=poll-max-ns,poll-grow=poll-grow,poll-shrink=poll-shrink,aio-max-batch=aio-max-batch`` Creates a dedicated event loop thread that devices can be assigned to. This is known as an IOThread. By default device emulation happens in vCPU threads or the main event loop thread. @@ -5337,7 +5337,11 @@ SRST the polling time when the algorithm detects it is spending too long polling without encountering events. - The polling parameters can be modified at run-time using the + The ``aio-max-batch`` parameter is the maximum number of requests + in a batch for the AIO engine, 0 means that the engine will use + its default. + + The IOThread parameters can be modified at run-time using the ``qom-set`` command (where ``iothread1`` is the IOThread's ``id``): -- cgit v1.1