lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  PHC 
Open Source and information security mailing list archives
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:   Thu, 12 Jul 2018 13:21:03 +0800
From:   Jason Wang <>
To:     "Michael S. Tsirkin" <>
Cc:     Tonghao Zhang <>,,,
        Linux Kernel Network Developers <>
Subject: Re: [PATCH net-next v5 0/4] net: vhost: improve performance when
 enable busyloop

On 2018年07月12日 11:34, Michael S. Tsirkin wrote:
> On Thu, Jul 12, 2018 at 11:26:12AM +0800, Jason Wang wrote:
>> 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 <> wrote:
>>>>>> On 2018年07月04日 12:31, wrote:
>>>>>>> From: Tonghao Zhang <>
>>>>>>> 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:
>>>>>>> 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
>> Thanks
> How does this patch work? vhost_vq_avail_empty can sleep,
> you are calling it within an rcu read side critical section.

Ok, I get your meaning. I have patches to access vring through 
get_user_pages + vmap() which should help here. (And it increase PPS 
about 10%-20%).

> That's not the only problem btw, another one is that the
> CPU time spent polling isn't accounted with the VM.

Yes, but it's not the 'issue' of this patch. And I believe cgroup can help?


>>>>>> Thanks

Powered by blists - more mailing lists