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From:   Vitaly Mayatskih <v.mayatskih@gmail.com>
Date:   Sun, 4 Nov 2018 11:40:36 -0500
Message-ID: <CAGF4SLhxvC5WN8W_ApoqMTe1i1r8FwX92Bb9UewpNwkKCZepnQ@mail.gmail.com>
Subject: Re: [PATCH 0/1] vhost: add vhost_blk driver
To:     mlevitsk@redhat.com
Cc:     "Michael S . Tsirkin" <mst@redhat.com>,
        Jason Wang <jasowang@redhat.com>,
        Paolo Bonzini <pbonzini@redhat.com>, kvm@vger.kernel.org,
        virtualization@lists.linux-foundation.org,
        linux-kernel@vger.kernel.org
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On Sun, Nov 4, 2018 at 6:57 AM Maxim Levitsky <mlevitsk@redhat.com> wrote:

> Hi!
> I am also working in this area, and so I am very intersted in this driver.
>
> > 1  171k  151k  148k 151k 195k  187k  175k
> If I understand correctly this is fio --numjobs=1?
> It looks like you are getting better that native performance over bare metal in
> E,F,G (vhost-blk cases in fact). Is this correct?

Yes. At such speeds it is a matter of how the workers are scheduled,
i.e. how good is batching. There are other factors why vhost-blk is on
par or slightly higher than fio running in userspace on bare metal,
but from my observation the right batching all through the stack is
more important.

> Could you share the full fio command line you have used?

sysctl -w vm.nr_hugepages=8300; numactl -p 1 -N 1 ./qemu-system-x86_64
-enable-kvm -cpu host -smp 16 -mem-prealloc -mem-path
/dev/hugepages/foo -m 8G -nographic -drive
if=none,id=drive0,format=raw,file=/dev/mapper/mirror-hello,cache=none
-device virtio-blk-pci,id=blk0,drive=drive0,num-queues=16 -drive
if=none,id=drive1,format=raw,file=/dev/mapper/mirror-volume,cache=none
-device vhost-blk-pci,id=blk1,drive=drive1,num-queues=16

for i in `seq 1 16`; do echo -n "$i "; ./fio --direct=1 --rw=randread
--ioengine=libaio --bs=4k --iodepth=128 --numjobs=$i --name=foo
--time_based --runtime=15 --group_reporting --filename=/dev/vda
--size=10g | grep -Po 'IOPS=[0-9\.]*k'; done

> Which IO device did you use for the test? NVME?

That was LVM mirror over 2 network disks. On the target side it was
LVM stripe over few NVMe's.

> Which system (cpu model/number of cores/etc) did you test on?

Dual socket: "model name    : Intel(R) Xeon(R) Gold 6142 CPU @
2.60GHz" with HT enabled, so 64 logical cores in total. The network
was something from Intel with 53 Gbps PHY and served by fm10k driver.

-- 
wbr, Vitaly