netdev - Re: [PATCH net-next v2] net: vhost: improve performance when enable busyloop

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Date:   Thu, 28 Jun 2018 14:44:09 +0800
From:   Tonghao Zhang <xiangxia.m.yue@...il.com>
To:     mst@...hat.com
Cc:     jasowang@...hat.com, virtualization@...ts.linux-foundation.org,
        Linux Kernel Network Developers <netdev@...r.kernel.org>,
        Tonghao Zhang <zhangtonghao@...ichuxing.com>
Subject: Re: [PATCH net-next v2] net: vhost: improve performance when enable busyloop

On Wed, Jun 27, 2018 at 11:58 PM Michael S. Tsirkin <mst@...hat.com> wrote:
>
> On Wed, Jun 27, 2018 at 10:24:43PM +0800, Jason Wang wrote:
> >
> >
> > On 2018年06月26日 13:17, xiangxia.m.yue@...il.com wrote:
> > > From: Tonghao Zhang <xiangxia.m.yue@...il.com>
> > >
> > > This patch improves the guest receive performance from
> > > host. On the handle_tx side, we poll the sock receive
> > > queue at the same time. handle_rx do that in the same way.
> > >
> > > For avoiding deadlock, change the code to lock the vq one
> > > by one and use the VHOST_NET_VQ_XX as a subclass for
> > > mutex_lock_nested. With the patch, qemu can set differently
> > > the busyloop_timeout for rx or tx queue.
> > >
> > > We set the poll-us=100us and use the iperf3 to test
> > > its throughput. The iperf3 command is shown as below.
> > >
> > > on the guest:
> > > iperf3  -s -D
> > >
> > > on the host:
> > > iperf3  -c 192.168.1.100 -i 1 -P 10 -t 10 -M 1400
> > >
> > > * With the patch:     23.1 Gbits/sec
> > > * Without the patch:  12.7 Gbits/sec
> > >
> > > Signed-off-by: Tonghao Zhang <zhangtonghao@...ichuxing.com>
> >
> > Thanks a lot for the patch. Looks good generally, but please split this big
> > patch into separate ones like:
> >
> > patch 1: lock vqs one by one
> > patch 2: replace magic number of lock annotation
> > patch 3: factor out generic busy polling logic to vhost_net_busy_poll()
> > patch 4: add rx busy polling in tx path.
> >
> > And please cc Michael in v3.
> >
> > Thanks
>
> Pls include host CPU utilization numbers. You can get them e.g. using
> vmstat.
OK, thanks.
> I suspect we also want the polling controllable e.g. through
> an ioctl.
>
> --
> MST