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([2001:b07:6468:f312:c8dd:75d4:99ab:290a]) by smtp.gmail.com with ESMTPSA id a17sm18478050wra.29.2020.10.19.06.25.24 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 19 Oct 2020 06:25:25 -0700 (PDT) Subject: Re: [PATCH v1 0/2] Add timeout mechanism to qmp actions To: Zhenyu Ye , Stefan Hajnoczi References: <20200810153811.GF14538@linux.fritz.box> <20200914132738.GL579094@stefanha-x1.localdomain> <7ad220bd-7ee5-1f66-b2e5-7dc57d72eb2e@huawei.com> <20200917154415.GB839531@stefanha-x1.localdomain> <20200917160054.GA2453251@dev> <5a5822ec-f3bc-a247-2b5a-f764b941c820@huawei.com> <20200918140628.GA2509473@dev> <1ba06b0d-3fcf-3676-f9e0-52875851ff19@huawei.com> <20200921111435.GA2524022@dev> <20201013100033.GB164611@stefanha-x1.localdomain> From: Paolo Bonzini Message-ID: <6fd02e2b-50fa-b667-efc6-47d1765bdd8c@redhat.com> Date: Mon, 19 Oct 2020 15:25:24 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.3.1 MIME-Version: 1.0 In-Reply-To: Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=pbonzini@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=windows-1252 Content-Language: en-US Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=216.205.24.124; envelope-from=pbonzini@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/10/19 01:44:30 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, NICE_REPLY_A=-0.001, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, 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, Kevin Wolf , Zhanghailiang , qemu-block@nongnu.org, qemu-devel@nongnu.org, xiexiangyou@huawei.com, armbru@redhat.com, mreitz@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 19/10/20 14:40, Zhenyu Ye wrote: > The kernel backtrace for io_submit in GUEST is: > > guest# ./offcputime -K -p `pgrep -nx fio` > b'finish_task_switch' > b'__schedule' > b'schedule' > b'io_schedule' > b'blk_mq_get_tag' > b'blk_mq_get_request' > b'blk_mq_make_request' > b'generic_make_request' > b'submit_bio' > b'blkdev_direct_IO' > b'generic_file_read_iter' > b'aio_read' > b'io_submit_one' > b'__x64_sys_io_submit' > b'do_syscall_64' > b'entry_SYSCALL_64_after_hwframe' > - fio (1464) > 40031912 > > And Linux io_uring can avoid the latency problem. What filesystem are you using? Paolo