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Mon, 11 Nov 2019 16:25:17 +0000 (UTC) Received: from dresden.str.redhat.com (ovpn-117-116.ams2.redhat.com [10.36.117.116]) by smtp.corp.redhat.com (Postfix) with ESMTPS id BB6314B4; Mon, 11 Nov 2019 16:25:05 +0000 (UTC) Subject: Re: [PATCH v2 03/15] block/block: add BDRV flag for io_uring To: Kevin Wolf , Stefan Hajnoczi References: <20191025160444.31632-1-stefanha@redhat.com> <20191025160444.31632-4-stefanha@redhat.com> <20191111105759.GB7297@linux.fritz.box> From: Max Reitz Autocrypt: addr=mreitz@redhat.com; prefer-encrypt=mutual; keydata= mQENBFXOJlcBCADEyyhOTsoa/2ujoTRAJj4MKA21dkxxELVj3cuILpLTmtachWj7QW+TVG8U /PsMCFbpwsQR7oEy8eHHZwuGQsNpEtNC2G/L8Yka0BIBzv7dEgrPzIu+W3anZXQW4702+uES U29G8TP/NGfXRRHGlbBIH9KNUnOSUD2vRtpOLXkWsV5CN6vQFYgQfFvmp5ZpPeUe6xNplu8V mcTw8OSEDW/ZnxJc8TekCKZSpdzYoxfzjm7xGmZqB18VFwgJZlIibt1HE0EB4w5GsD7x5ekh awIe3RwoZgZDLQMdOitJ1tUc8aqaxvgA4tz6J6st8D8pS//m1gAoYJWGwwIVj1DjTYLtABEB AAG0HU1heCBSZWl0eiA8bXJlaXR6QHJlZGhhdC5jb20+iQFTBBMBCAA9AhsDBQkSzAMABQsJ CAcCBhUICQoLAgQWAgMBAh4BAheABQJVzie5FRhoa3A6Ly9rZXlzLmdudXBnLm5ldAAKCRD0 B9sAYdXPQDcIB/9uNkbYEex1rHKz3mr12uxYMwLOOFY9fstP5aoVJQ1nWQVB6m2cfKGdcRe1 2/nFaHSNAzT0NnKz2MjhZVmcrpyd2Gp2QyISCfb1FbT82GMtXFj1wiHmPb3CixYmWGQUUh+I AvUqsevLA+WihgBUyaJq/vuDVM1/K9Un+w+Tz5vpeMidlIsTYhcsMhn0L9wlCjoucljvbDy/ 8C9L2DUdgi3XTa0ORKeflUhdL4gucWoAMrKX2nmPjBMKLgU7WLBc8AtV+84b9OWFML6NEyo4 4cP7cM/07VlJK53pqNg5cHtnWwjHcbpGkQvx6RUx6F1My3y52vM24rNUA3+ligVEgPYBuQEN BFXOJlcBCADAmcVUNTWT6yLWQHvxZ0o47KCP8OcLqD+67T0RCe6d0LP8GsWtrJdeDIQk+T+F xO7DolQPS6iQ6Ak2/lJaPX8L0BkEAiMuLCKFU6Bn3lFOkrQeKp3u05wCSV1iKnhg0UPji9V2 W5eNfy8F4ZQHpeGUGy+liGXlxqkeRVhLyevUqfU0WgNqAJpfhHSGpBgihUupmyUg7lfUPeRM DzAN1pIqoFuxnN+BRHdAecpsLcbR8sQddXmDg9BpSKozO/JyBmaS1RlquI8HERQoe6EynJhd 64aICHDfj61rp+/0jTIcevxIIAzW70IadoS/y3DVIkuhncgDBvGbF3aBtjrJVP+5ABEBAAGJ ASUEGAEIAA8FAlXOJlcCGwwFCRLMAwAACgkQ9AfbAGHVz0CbFwf9F/PXxQR9i4N0iipISYjU sxVdjJOM2TMut+ZZcQ6NSMvhZ0ogQxJ+iEQ5OjnIputKvPVd5U7WRh+4lF1lB/NQGrGZQ1ic alkj6ocscQyFwfib+xIe9w8TG1CVGkII7+TbS5pXHRxZH1niaRpoi/hYtgzkuOPp35jJyqT/ /ELbqQTDAWcqtJhzxKLE/ugcOMK520dJDeb6x2xVES+S5LXby0D4juZlvUj+1fwZu+7Io5+B bkhSVPb/QdOVTpnz7zWNyNw+OONo1aBUKkhq2UIByYXgORPFnbfMY7QWHcjpBVw9MgC4tGeF R4bv+1nAMMxKmb5VvQCExr0eFhJUAHAhVg== Message-ID: <6e8cf473-d3e9-c743-d2bd-75a0d955e6c6@redhat.com> Date: Mon, 11 Nov 2019 17:25:04 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.1.1 MIME-Version: 1.0 In-Reply-To: <20191111105759.GB7297@linux.fritz.box> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-Mimecast-Spam-Score: 0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="wv1QQczEPh1MLbDCfJNuUsLnsNefdwFAk" X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 207.211.31.120 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 Zheng , oleksandr@redhat.com, Maxim Levitsky , qemu-block@nongnu.org, Julia Suvorova , qemu-devel@nongnu.org, Markus Armbruster , Paolo Bonzini , Aarushi Mehta Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --wv1QQczEPh1MLbDCfJNuUsLnsNefdwFAk Content-Type: multipart/mixed; boundary="mTnm7e8iVeyIPpldY9ww7k1gXk60uVcjQ" --mTnm7e8iVeyIPpldY9ww7k1gXk60uVcjQ Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable On 11.11.19 11:57, Kevin Wolf wrote: > Am 25.10.2019 um 18:04 hat Stefan Hajnoczi geschrieben: >> From: Aarushi Mehta >> >> Signed-off-by: Aarushi Mehta >> Reviewed-by: Maxim Levitsky >> Signed-off-by: Stefan Hajnoczi >> --- >> include/block/block.h | 1 + >> 1 file changed, 1 insertion(+) >> >> diff --git a/include/block/block.h b/include/block/block.h >> index 89606bd9f8..bdb48dcd1b 100644 >> --- a/include/block/block.h >> +++ b/include/block/block.h >> @@ -126,6 +126,7 @@ typedef struct HDGeometry { >> ignoring the format layer */ >> #define BDRV_O_NO_IO 0x10000 /* don't initialize for I/O */ >> #define BDRV_O_AUTO_RDONLY 0x20000 /* degrade to read-only if opening r= ead-write fails */ >> +#define BDRV_O_IO_URING 0x40000 /* use io_uring instead of the threa= d pool */ >=20 > Why do we need a new (global!) flag rather than a driver-specific option > for file-posix? This looks wrong to me, the flag has no sensible meaning > for any other driver. >=20 > (Yes, BDRV_O_NATIVE_AIO is wrong, too, but compatibility means we can't > remove it easily.) To add to that, Kevin and me had a short talk on IRC, and it seemed like the reason would be that it=E2=80=99s easier to use this way than an option would be. To me, the problem seems to be that it=E2=80=99s only easier to use because= of the option inheritance we have in the block layer (so you can set this flag on a qcow2 node and its file node will have it, too). But naturally this inheritance is a bit of magic (because qemu has to guess where you probably want the flag to end up), so I=E2=80=99d too rather avoi= d adding to it. OTOH, I wonder whether ease of use is really that important here. Would people who want to use io_uring really care about a command line that=E2=80= =99s going to be a bit more complicated than just -drive file=3Dfoo.img,format=3D$imgfmt,aio=3Dio_uring,if=3D$interface? (Na= mely file.aio in this case, or maybe even a full-on block graph definition.) Max --mTnm7e8iVeyIPpldY9ww7k1gXk60uVcjQ-- --wv1QQczEPh1MLbDCfJNuUsLnsNefdwFAk Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEEkb62CjDbPohX0Rgp9AfbAGHVz0AFAl3Ji2AACgkQ9AfbAGHV z0DvCQf/dKHfQwr8HCfFXmjwU2FYvMTlPQPdr+zAeCUCqZ/GZN0/jEyYXlNzeEAP z68vOI/yFAW/TXTCS/xrS2upk4aBpZoaocP8fb7l+2x9qHDR77H2wIxZsS8YjL/G StLwODzcvCcGyj5iv/4TUyl9wJVqH/PD0Fz1C6H0ZsaMfWJCuLXVJ6n6COqDrzbg k+qwOjK4UxBL54RTfpa8cU4u6npb7Su45Vm6SfBv15IBC3et83txnbSKM5NAG5rH iWXA00z+JgmuaGkEonDW2wlEBIEqWFi1NVZKOo2FvZU571HDEJIYy4mMAokbhOv/ nG3Q3nh5JRXs1rVy7z/5uB0mIMNJ3Q== =Dbqd -----END PGP SIGNATURE----- --wv1QQczEPh1MLbDCfJNuUsLnsNefdwFAk--