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Wed, 8 Sep 2021 15:21:19 +0000 From: John Levon To: Stefan Hajnoczi Subject: Re: [PATCH RFC server v2 05/11] vfio-user: run vfio-user context Thread-Topic: [PATCH RFC server v2 05/11] vfio-user: run vfio-user context Thread-Index: AQHXm2yIPjWEzOwcWUWSWCWzNjp1MquaK6sAgAAK7oCAABebAIAABUaA Date: Wed, 8 Sep 2021 15:21:19 +0000 Message-ID: References: <3c043becf2b6e820f5392e0cadb465d5d9b9e6f8.1630084211.git.jag.raman@oracle.com> In-Reply-To: Accept-Language: en-GB, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: authentication-results: redhat.com; dkim=none (message not signed) header.d=none;redhat.com; dmarc=none action=none header.from=nutanix.com; x-ms-publictraffictype: Email x-ms-office365-filtering-correlation-id: 43924f1e-3c4c-4241-2e1e-08d972dc4f37 x-ms-traffictypediagnostic: MN2PR02MB6416: x-ms-exchange-transport-forked: True x-microsoft-antispam-prvs: x-proofpoint-crosstenant: true x-ms-oob-tlc-oobclassifiers: OLM:8882; x-ms-exchange-senderadcheck: 1 x-ms-exchange-antispam-relay: 0 x-microsoft-antispam: BCL:0; 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envelope-from=john.levon@nutanix.com; helo=mx0b-002c1b01.pphosted.com X-Spam_score_int: -24 X-Spam_score: -2.5 X-Spam_bar: -- X-Spam_report: (-2.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.393, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, 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: "elena.ufimtseva@oracle.com" , "john.g.johnson@oracle.com" , "thuth@redhat.com" , Jagannathan Raman , Swapnil Ingle , "philmd@redhat.com" , "qemu-devel@nongnu.org" , "alex.williamson@redhat.com" , "marcandre.lureau@gmail.com" , Thanos Makatos , "alex.bennee@linaro.org" Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Wed, Sep 08, 2021 at 04:02:22PM +0100, Stefan Hajnoczi wrote: > > We'd have to have a whole separate API to do that, so a separate thread= seems a > > better approach? >=20 > Whether to support non-blocking properly in libvfio-user is a decision > for you. If libvfio-user doesn't support non-blocking, then QEMU should > run a dedicated thread instead of the partially non-blocking approach in > this patch. Right, sure. At this point we don't have any plans to implement a separate = async API due to the amount of work involved.=20 > A non-blocking approach is nice when there are many devices hosted in a > single process or a lot of async replies (which requires extra thread > synchronization with the blocking approach). I suppose this would be more of a problem with devices where the I/O path h= as to be handled via the socket. regards john=