netdev - Re: [PATCH net-next v5 0/4] net: vhost: improve performance when enable busyloop

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Date:   Thu, 12 Jul 2018 11:26:12 +0800
From:   Jason Wang <jasowang@...hat.com>
To:     "Michael S. Tsirkin" <mst@...hat.com>
Cc:     Tonghao Zhang <xiangxia.m.yue@...il.com>,
        makita.toshiaki@....ntt.co.jp,
        virtualization@...ts.linux-foundation.org,
        Linux Kernel Network Developers <netdev@...r.kernel.org>
Subject: Re: [PATCH net-next v5 0/4] net: vhost: improve performance when
 enable busyloop



On 2018年07月11日 19:59, Michael S. Tsirkin wrote:
> On Wed, Jul 11, 2018 at 01:12:59PM +0800, Jason Wang wrote:
>>
>> On 2018年07月11日 11:49, Tonghao Zhang wrote:
>>> On Wed, Jul 11, 2018 at 10:56 AM Jason Wang <jasowang@...hat.com> wrote:
>>>>
>>>> On 2018年07月04日 12:31, xiangxia.m.yue@...il.com wrote:
>>>>> From: Tonghao Zhang <xiangxia.m.yue@...il.com>
>>>>>
>>>>> This patches improve the guest receive and transmit performance.
>>>>> On the handle_tx side, we poll the sock receive queue at the same time.
>>>>> handle_rx do that in the same way.
>>>>>
>>>>> For more performance report, see patch 4.
>>>>>
>>>>> v4 -> v5:
>>>>> fix some issues
>>>>>
>>>>> v3 -> v4:
>>>>> fix some issues
>>>>>
>>>>> v2 -> v3:
>>>>> This patches are splited from previous big patch:
>>>>> http://patchwork.ozlabs.org/patch/934673/
>>>>>
>>>>> Tonghao Zhang (4):
>>>>>      vhost: lock the vqs one by one
>>>>>      net: vhost: replace magic number of lock annotation
>>>>>      net: vhost: factor out busy polling logic to vhost_net_busy_poll()
>>>>>      net: vhost: add rx busy polling in tx path
>>>>>
>>>>>     drivers/vhost/net.c   | 108 ++++++++++++++++++++++++++++----------------------
>>>>>     drivers/vhost/vhost.c |  24 ++++-------
>>>>>     2 files changed, 67 insertions(+), 65 deletions(-)
>>>>>
>>>> Hi, any progress on the new version?
>>>>
>>>> I plan to send a new series of packed virtqueue support of vhost. If you
>>>> plan to send it soon, I can wait. Otherwise, I will send my series.
>>> I rebase the codes. and find there is no improvement anymore, the
>>> patches of  makita  may solve the problem. jason you may send your
>>> patches, and I will do some research on busypoll.
>> I see. Maybe you can try some bi-directional traffic.
>>
>> Btw, lots of optimizations could be done for busy polling. E.g integrating
>> with host NAPI busy polling or a 100% busy polling vhost_net. You're welcome
>> to work or propose new ideas.
>>
>> Thanks
> It seems clear we do need adaptive polling.

Yes.

>   The difficulty with NAPI
> polling is it can't access guest memory easily. But maybe
> get_user_pages on the polled memory+NAPI polling can work.

You mean something like zerocopy? Looks like we can do busy polling 
without it. I mean something like 
https://patchwork.kernel.org/patch/8707511/.

Thanks

>
>>>> Thanks