From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id A7481C433F5 for ; Sat, 8 Oct 2022 08:43:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229782AbiJHIn6 (ORCPT ); Sat, 8 Oct 2022 04:43:58 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38670 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229539AbiJHIn5 (ORCPT ); Sat, 8 Oct 2022 04:43:57 -0400 Received: from out30-44.freemail.mail.aliyun.com (out30-44.freemail.mail.aliyun.com [115.124.30.44]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C9C1F56BBE; Sat, 8 Oct 2022 01:43:53 -0700 (PDT) X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R171e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=ay29a033018046049;MF=ziyangzhang@linux.alibaba.com;NM=1;PH=DS;RN=8;SR=0;TI=SMTPD_---0VRbkghb_1665218629; Received: from 30.97.56.201(mailfrom:ZiyangZhang@linux.alibaba.com fp:SMTPD_---0VRbkghb_1665218629) by smtp.aliyun-inc.com; Sat, 08 Oct 2022 16:43:50 +0800 Message-ID: <50827796-af93-4af5-4121-dc13c31a67fc@linux.alibaba.com> Date: Sat, 8 Oct 2022 16:43:47 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:91.0) Gecko/20100101 Thunderbird/91.13.0 Subject: Re: ublk-qcow2: ublk-qcow2 is available Content-Language: en-US To: Ming Lei , Stefan Hajnoczi Cc: Stefan Hajnoczi , io-uring@vger.kernel.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, "Denis V. Lunev" , Xiaoguang Wang References: From: Ziyang Zhang In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org On 2022/10/5 12:18, Ming Lei wrote: > On Tue, Oct 04, 2022 at 09:53:32AM -0400, Stefan Hajnoczi wrote: >> On Tue, 4 Oct 2022 at 05:44, Ming Lei wrote: >>> >>> On Mon, Oct 03, 2022 at 03:53:41PM -0400, Stefan Hajnoczi wrote: >>>> On Fri, Sep 30, 2022 at 05:24:11PM +0800, Ming Lei wrote: >>>>> ublk-qcow2 is available now. >>>> >>>> Cool, thanks for sharing! >>>> >>>>> >>>>> So far it provides basic read/write function, and compression and snapshot >>>>> aren't supported yet. The target/backend implementation is completely >>>>> based on io_uring, and share the same io_uring with ublk IO command >>>>> handler, just like what ublk-loop does. >>>>> >>>>> Follows the main motivations of ublk-qcow2: >>>>> >>>>> - building one complicated target from scratch helps libublksrv APIs/functions >>>>> become mature/stable more quickly, since qcow2 is complicated and needs more >>>>> requirement from libublksrv compared with other simple ones(loop, null) >>>>> >>>>> - there are several attempts of implementing qcow2 driver in kernel, such as >>>>> ``qloop`` [2], ``dm-qcow2`` [3] and ``in kernel qcow2(ro)`` [4], so ublk-qcow2 >>>>> might useful be for covering requirement in this field >>>>> >>>>> - performance comparison with qemu-nbd, and it was my 1st thought to evaluate >>>>> performance of ublk/io_uring backend by writing one ublk-qcow2 since ublksrv >>>>> is started >>>>> >>>>> - help to abstract common building block or design pattern for writing new ublk >>>>> target/backend >>>>> >>>>> So far it basically passes xfstest(XFS) test by using ublk-qcow2 block >>>>> device as TEST_DEV, and kernel building workload is verified too. Also >>>>> soft update approach is applied in meta flushing, and meta data >>>>> integrity is guaranteed, 'make test T=qcow2/040' covers this kind of >>>>> test, and only cluster leak is reported during this test. >>>>> >>>>> The performance data looks much better compared with qemu-nbd, see >>>>> details in commit log[1], README[5] and STATUS[6]. And the test covers both >>>>> empty image and pre-allocated image, for example of pre-allocated qcow2 >>>>> image(8GB): >>>>> >>>>> - qemu-nbd (make test T=qcow2/002) >>>> >>>> Single queue? >>> >>> Yeah. >>> >>>> >>>>> randwrite(4k): jobs 1, iops 24605 >>>>> randread(4k): jobs 1, iops 30938 >>>>> randrw(4k): jobs 1, iops read 13981 write 14001 >>>>> rw(512k): jobs 1, iops read 724 write 728 >>>> >>>> Please try qemu-storage-daemon's VDUSE export type as well. The >>>> command-line should be similar to this: >>>> >>>> # modprobe virtio_vdpa # attaches vDPA devices to host kernel >>> >>> Not found virtio_vdpa module even though I enabled all the following >>> options: >>> >>> --- vDPA drivers >>> vDPA device simulator core >>> vDPA simulator for networking device >>> vDPA simulator for block device >>> VDUSE (vDPA Device in Userspace) support >>> Intel IFC VF vDPA driver >>> Virtio PCI bridge vDPA driver >>> vDPA driver for Alibaba ENI >>> >>> BTW, my test environment is VM and the shared data is done in VM too, and >>> can virtio_vdpa be used inside VM? >> >> I hope Xie Yongji can help explain how to benchmark VDUSE. >> >> virtio_vdpa is available inside guests too. Please check that >> VIRTIO_VDPA ("vDPA driver for virtio devices") is enabled in "Virtio >> drivers" menu. >> >>> >>>> # modprobe vduse >>>> # qemu-storage-daemon \ >>>> --blockdev file,filename=test.qcow2,cache.direct=of|off,aio=native,node-name=file \ >>>> --blockdev qcow2,file=file,node-name=qcow2 \ >>>> --object iothread,id=iothread0 \ >>>> --export vduse-blk,id=vduse0,name=vduse0,num-queues=$(nproc),node-name=qcow2,writable=on,iothread=iothread0 >>>> # vdpa dev add name vduse0 mgmtdev vduse >>>> >>>> A virtio-blk device should appear and xfstests can be run on it >>>> (typically /dev/vda unless you already have other virtio-blk devices). >>>> >>>> Afterwards you can destroy the device using: >>>> >>>> # vdpa dev del vduse0 >>>> >>>>> >>>>> - ublk-qcow2 (make test T=qcow2/022) >>>> >>>> There are a lot of other factors not directly related to NBD vs ublk. In >>>> order to get an apples-to-apples comparison with qemu-* a ublk export >>>> type is needed in qemu-storage-daemon. That way only the difference is >>>> the ublk interface and the rest of the code path is identical, making it >>>> possible to compare NBD, VDUSE, ublk, etc more precisely. >>> >>> Maybe not true. >>> >>> ublk-qcow2 uses io_uring to handle all backend IO(include meta IO) completely, >>> and so far single io_uring/pthread is for handling all qcow2 IOs and IO >>> command. >> >> qemu-nbd doesn't use io_uring to handle the backend IO, so we don't > > I tried to use it via --aio=io_uring for setting up qemu-nbd, but not succeed. > >> know whether the benchmark demonstrates that ublk is faster than NBD, >> that the ublk-qcow2 implementation is faster than qemu-nbd's qcow2, >> whether there are miscellaneous implementation differences between >> ublk-qcow2 and qemu-nbd (like using the same io_uring context for both >> ublk and backend IO), or something else. > > The theory shouldn't be too complicated: > > 1) io uring passthough(pt) communication is fast than socket, and io command > is carried over io_uring pt commands, and should be fast than virio > communication too. > > 2) io uring io handling is fast than libaio which is taken in the > test on qemu-nbd, and all qcow2 backend io(include meta io) is handled > by io_uring. > > https://github.com/ming1/ubdsrv/blob/master/tests/common/qcow2_common > > 3) ublk uses one single io_uring to handle all io commands and qcow2 > backend IOs, so batching handling is common, and it is easy to see > dozens of IOs/io commands handled in single syscall, or even more. > >> >> I'm suggesting measuring changes to just 1 variable at a time. >> Otherwise it's hard to reach a conclusion about the root cause of the >> performance difference. Let's learn why ublk-qcow2 performs well. > > Turns out the latest Fedora 37-beta doesn't support vdpa yet, so I built > qemu from the latest github tree, and finally it starts to work. And test kernel > is v6.0 release. > > Follows the test result, and all three devices are setup as single > queue, and all tests are run in single job, still done in one VM, and > the test images are stored on XFS/virito-scsi backed SSD. > > The 1st group tests all three block device which is backed by empty > qcow2 image. > > The 2nd group tests all the three block devices backed by pre-allocated > qcow2 image. > > Except for big sequential IO(512K), there is still not small gap between > vdpa-virtio-blk and ublk. > > 1. run fio on block device over empty qcow2 image > 1) qemu-nbd > running qcow2/001 > run perf test on empty qcow2 image via nbd > fio (nbd(/mnt/data/ublk_null_8G_nYbgF.qcow2), libaio, bs 4k, dio, hw queues:1)... > randwrite: jobs 1, iops 8549 > randread: jobs 1, iops 34829 > randrw: jobs 1, iops read 11363 write 11333 > rw(512k): jobs 1, iops read 590 write 597 > > > 2) ublk-qcow2 > running qcow2/021 > run perf test on empty qcow2 image via ublk > fio (ublk/qcow2( -f /mnt/data/ublk_null_8G_s761j.qcow2), libaio, bs 4k, dio, hw queues:1, uring_comp: 0, get_data: 0). > randwrite: jobs 1, iops 16086 > randread: jobs 1, iops 172720 > randrw: jobs 1, iops read 35760 write 35702 > rw(512k): jobs 1, iops read 1140 write 1149 > > 3) vdpa-virtio-blk > running debug/test_dev > run io test on specified device > fio (vdpa(/dev/vdc), libaio, bs 4k, dio, hw queues:1)... > randwrite: jobs 1, iops 8626 > randread: jobs 1, iops 126118 > randrw: jobs 1, iops read 17698 write 17665 > rw(512k): jobs 1, iops read 1023 write 1031 > > > 2. run fio on block device over pre-allocated qcow2 image > 1) qemu-nbd > running qcow2/002 > run perf test on pre-allocated qcow2 image via nbd > fio (nbd(/mnt/data/ublk_data_8G_sc0SB.qcow2), libaio, bs 4k, dio, hw queues:1)... > randwrite: jobs 1, iops 21439 > randread: jobs 1, iops 30336 > randrw: jobs 1, iops read 11476 write 11449 > rw(512k): jobs 1, iops read 718 write 722 > > 2) ublk-qcow2 > running qcow2/022 > run perf test on pre-allocated qcow2 image via ublk > fio (ublk/qcow2( -f /mnt/data/ublk_data_8G_yZiaJ.qcow2), libaio, bs 4k, dio, hw queues:1, uring_comp: 0, get_data: 0). > randwrite: jobs 1, iops 98757 > randread: jobs 1, iops 110246 > randrw: jobs 1, iops read 47229 write 47161 > rw(512k): jobs 1, iops read 1416 write 1427 > > 3) vdpa-virtio-blk > running debug/test_dev > run io test on specified device > fio (vdpa(/dev/vdc), libaio, bs 4k, dio, hw queues:1)... > randwrite: jobs 1, iops 47317 > randread: jobs 1, iops 74092 > randrw: jobs 1, iops read 27196 write 27234 > rw(512k): jobs 1, iops read 1447 write 1458 > > Hi All, We are interested in VDUSE vs UBLK, too. And I have tested them with nullblk backend. Let me share some results here. I setup UBLK with: ublk add -t loop -f /dev/nullb0 -d QUEUE_DEPTH -q NR_QUEUE I setup VDUSE with: qemu-storage-daemon \ --chardev socket,id=charmonitor,path=/tmp/qmp.sock,server=on,wait=off \ --monitor chardev=charmonitor \ --blockdev driver=host_device,cache.direct=on,filename=/dev/nullb0,node-name=disk0 \ --export vduse-blk,id=test,node-name=disk0,name=vduse_test,writable=on,num-queues=NR_QUEUE,queue-size=QUEUE_DEPTH Here QUEUE_DEPTH is 1, 32 or 128 and NR_QUEUE is 1 or 4. Note: (1) VDUSE requires QUEUE_DEPTH >= 2. I cannot setup QUEUE_DEPTH to 1. (2) I use qemu 7.1.0-rc3. It supports vduse-blk. (3) I do not use ublk null target so that the test is fair. (4) I setup fio with direct=1, bs=4k. ------------------------------ 1 job 1 iodepth, lat（usec) vduse ublk seq-read 22.55 11.15 rand-read 22.49 11.17 seq-write 25.67 10.25 rand-write 24.13 10.16 ------------------------------ 1 job 32 iodepth, iops（k) vduse ublk seq-read 166 207 rand-read 150 204 seq-write 131 359 rand-write 129 363 ------------------------------ 4job 128 iodepth, iops (k) vduse ublk seq-read 318 984 rand-read 307 929 seq-write 221 924 rand-write 217 917 Regards, Zhang