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Thu, 24 Jul 2025 20:36:06 +0000 (UTC) Received: from localhost (unknown [10.2.16.247]) by mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 323371956089; Thu, 24 Jul 2025 20:36:04 +0000 (UTC) Date: Thu, 24 Jul 2025 16:36:03 -0400 From: Stefan Hajnoczi To: Bernd Schubert Cc: Brian Song , "qemu-block@nongnu.org" , "qemu-devel@nongnu.org" , "armbru@redhat.com" , "fam@euphon.net" , "hreitz@redhat.com" , "kwolf@redhat.com" Subject: Re: [PATCH RFC 1/1] block/export: FUSE-over-io_uring Support for QEMU FUSE Exports Message-ID: <20250724203603.GA573965@fedora> References: <20250716183824.216257-1-hibriansong@gmail.com> <20250716183824.216257-2-hibriansong@gmail.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="CZFVtOZlLmvJyApo" Content-Disposition: inline In-Reply-To: X-Scanned-By: MIMEDefang 3.0 on 10.30.177.15 Received-SPF: pass client-ip=170.10.129.124; envelope-from=stefanha@redhat.com; helo=us-smtp-delivery-124.mimecast.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=-0.45, 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_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, SPF_HELO_PASS=-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: 2.1.29 Precedence: list List-Id: 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 --CZFVtOZlLmvJyApo Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, Jul 21, 2025 at 01:51:44PM +0000, Bernd Schubert wrote: > On 7/16/25 20:38, Brian Song wrote: > > - ret =3D io_uring_queue_init(FDMON_IO_URING_ENTRIES, &ctx->fdmon_io= _uring, 0); > > + ret =3D io_uring_queue_init(FDMON_IO_URING_ENTRIES, > > + &ctx->fdmon_io_uring, flags); > > if (ret !=3D 0) { > > error_setg_errno(errp, -ret, "Failed to initialize io_uring"); > > return; >=20 > I need test these flags again, might be worthful for qemu as well >=20 > /* These flags should help to increase performance, but actually > * make it a bit slower - reason should get investigated. > */ > if (0) { > /* Has the main slow down effect */ > params.flags |=3D IORING_SETUP_SINGLE_ISSUER; >=20 > // params.flags |=3D IORING_SETUP_DEFER_TASKRUN; > params.flags |=3D IORING_SETUP_TASKRUN_FLAG; >=20 > /* Second main effect to make it slower */ > params.flags |=3D IORING_SETUP_COOP_TASKRUN; > } I measured the following using fio bs=3D4k in a 4 vCPU guest with 1 IOThread using a virtio-blk disk backed by a local NVMe drive: IOPS IOPS Benchmark SINGLE_ISSUER SINGLE_ISSUER|COOP_TASKRUN|TASKRUN= _FLAG randread iodepth=3D1 54,045 (+1.2%) 54,189 (+1.5%) randread iodepth=3D64 318,135 (+0.1%) 315,632 (-0.68%) randwrite iodepth=3D1 141,918 (-0.44%) 143,337 (+0.55%) randwrite iodepth=3D64 323,948 (-0.015%) 322,755 (-0.38%) The differences are so small that I'd rather not merge the code changes. I will post an RFC series just to archive the patches in case they are needed again in the future. You can find detailed benchmarking results here including the fio output, fio command-line, and guest libvirt domain XML: https://gitlab.com/stefanha/virt-playbooks/-/tree/io_uring-flags/notebook/f= io-output https://gitlab.com/stefanha/virt-playbooks/-/blob/io_uring-flags/files/fio.= sh https://gitlab.com/stefanha/virt-playbooks/-/blob/io_uring-flags/files/test= =2Exml.j2 Stefan --CZFVtOZlLmvJyApo Content-Type: application/pgp-signature; name=signature.asc -----BEGIN PGP SIGNATURE----- iQEzBAEBCgAdFiEEhpWov9P5fNqsNXdanKSrs4Grc8gFAmiCmTMACgkQnKSrs4Gr c8i5UAf/cmTZvXwKqKW9K3WDBgvxgjhteqGzKC7HcG6CIDNDHnMrssTlB27fp3om buhiwYtpWYgVAxGJbzwa7X5N+i1d2gL92oov7VIYP/gqLtrOwQIdsdt9UVW/le2i F4MTUvNXEzvPBp5aRiSrtSrW5boEcijFnkG5jF74o7sAJDmn2UIxkFNLVA5OEjHP WZzF4awZDKPPWJAxXTv3EAbgQHAVN0Gydd6aPpjv56AJ6dHgDtRREfuvH6yPUN8l 55cPf714lGWNGhocNBEPTLxNJcqjwU+AWEiLOzHhBndZMp9Q/PqvX3T34UHiyUNo aW053cQMjhsGS5Tnbw6Lcd22IZNqwQ== =cmZF -----END PGP SIGNATURE----- --CZFVtOZlLmvJyApo--