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Mon, 10 Aug 2020 15:38:12 +0000 (UTC) Date: Mon, 10 Aug 2020 17:38:11 +0200 From: Kevin Wolf To: Zhenyu Ye Subject: Re: [PATCH v1 0/2] Add timeout mechanism to qmp actions Message-ID: <20200810153811.GF14538@linux.fritz.box> References: <20200810145246.1049-1-yezhenyu2@huawei.com> MIME-Version: 1.0 In-Reply-To: <20200810145246.1049-1-yezhenyu2@huawei.com> X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=kwolf@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Received-SPF: pass client-ip=207.211.31.120; envelope-from=kwolf@redhat.com; helo=us-smtp-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/08/10 03:31:01 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -30 X-Spam_score: -3.1 X-Spam_bar: --- X-Spam_report: (-3.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1, 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_H3=-0.01, RCVD_IN_MSPIKE_WL=-0.01, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: fam@euphon.net, qemu-block@nongnu.org, armbru@redhat.com, xiexiangyou@huawei.com, qemu-devel@nongnu.org, stefanha@redhat.com, pbonzini@redhat.com, mreitz@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Am 10.08.2020 um 16:52 hat Zhenyu Ye geschrieben: > Before doing qmp actions, we need to lock the qemu_global_mutex, > so the qmp actions should not take too long time. > > Unfortunately, some qmp actions need to acquire aio context and > this may take a long time. The vm will soft lockup if this time > is too long. Do you have a specific situation in mind where getting the lock of an AioContext can take a long time? I know that the main thread can block for considerable time, but QMP commands run in the main thread, so this patch doesn't change anything for this case. It would be effective if an iothread blocks, but shouldn't everything running in an iothread be asynchronous and therefore keep the AioContext lock only for a short time? Kevin