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David Alan Gilbert" , Eric Blake Subject: Re: [PATCH V2 4/4] qemu-options: Introduce new flag for iothread In-Reply-To: <20260121064110.28760-4-zhangckid@gmail.com> (Zhang Chen's message of "Wed, 21 Jan 2026 14:41:10 +0800") References: <20260121064110.28760-1-zhangckid@gmail.com> <20260121064110.28760-4-zhangckid@gmail.com> Date: Fri, 23 Jan 2026 14:04:15 +0100 Message-ID: <87ldhoa3ao.fsf@pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) MIME-Version: 1.0 Content-Type: text/plain X-Scanned-By: MIMEDefang 3.0 on 10.30.177.12 Received-SPF: pass client-ip=170.10.129.124; envelope-from=armbru@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: 12 X-Spam_score: 1.2 X-Spam_bar: + X-Spam_report: (1.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.079, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=0.001, RCVD_IN_SBL_CSS=3.335, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=no autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: qemu development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Zhang Chen writes: > This demand comes from Cloud Native ecosystem. > User want to manage resources more flexible like containers (Kata container). > The real workload maybe changed(runc) in the VM without VM reboot, > It may need hotplug/unplug different multi disks with multi iothreads to meet > high level scheduler's needs(like K8s). > > Signed-off-by: Zhang Chen > --- > qemu-options.hx | 9 ++++++++- > 1 file changed, 8 insertions(+), 1 deletion(-) > > diff --git a/qemu-options.hx b/qemu-options.hx > index ec92723f10..9afe9d4ebb 100644 > --- a/qemu-options.hx > +++ b/qemu-options.hx > @@ -6352,7 +6352,7 @@ 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,aio-max-batch=aio-max-batch`` > + ``-object iothread,id=id,attached=attached,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. > @@ -6376,6 +6376,13 @@ SRST > for many cases but can be adjusted based on knowledge of the > workload and/or host device latency. > > + The ``attached`` parameter is a flag to show whether the iothread > + is attached to an actual device(for example virtio-blk). In hotplug > + scenario, user can add multiple "-object iothread" and multiple > + devices (like virtio-blk). When user hotunplug the devices can keep > + the iothreads as a thread pool, following the new hotplug devices can > + attach to the released iothread. > + > The ``poll-max-ns`` parameter is the maximum number of > nanoseconds to busy wait for events. Polling can be disabled by > setting this value to 0. You're documenting something that does not exist: $ qemu-system-aarch64 -object iothread,id=iot0,attached=off upstream-qemu: -object iothread,id=iot0,attached=off: Invalid parameter 'attached' The properties of iothread objects are defined in type IothreadProperties in qapi/qom.json.