From: "Michael S. Tsirkin" <mst@redhat.com>
To: Shirley Ma <mashirle@us.ibm.com>
Cc: Sridhar Samudrala <sri@us.ibm.com>,
Steve Dobbelstein <steved@us.ibm.com>,
David Miller <davem@davemloft.net>,
kvm@vger.kernel.org, mashirle@linux.vnet.ibm.com,
netdev@vger.kernel.org
Subject: Re: Network performance with small packets
Date: Wed, 2 Feb 2011 12:48:43 +0200 [thread overview]
Message-ID: <20110202104843.GB8505@redhat.com> (raw)
In-Reply-To: <1296630891.26937.870.camel@localhost.localdomain>
On Tue, Feb 01, 2011 at 11:14:51PM -0800, Shirley Ma wrote:
> On Wed, 2011-02-02 at 08:29 +0200, Michael S. Tsirkin wrote:
> > On Tue, Feb 01, 2011 at 10:19:09PM -0800, Shirley Ma wrote:
> > > On Tue, 2011-02-01 at 22:05 -0800, Shirley Ma wrote:
> > > >
> > > > The way I am changing is only when netif queue has stopped, then
> > we
> > > > start to count num_free descriptors to send the signal to wake
> > netif
> > > > queue.
> > >
> > > I forgot to mention, the code change I am making is in guest kernel,
> > in
> > > xmit call back only wake up the queue when it's stopped && num_free
> > >=
> > > 1/2 *vq->num, I add a new API in virtio_ring.
> >
> > Interesting. Yes, I agree an API extension would be helpful. However,
> > wouldn't just the signaling reduction be enough, without guest
> > changes?
>
> w/i guest change, I played around the parameters,for example: I could
> get 3.7Gb/s with 42% CPU BW increasing from 2.5Gb/s for 1K message size,
> w/i dropping packet, I was able to get up to 6.2Gb/s with similar CPU
> usage.
We need to consider them separately IMO. What's the best we can get
without guest change? And which parameters give it?
There will always be old guests, and as far as I can tell
it should work better from host.
> > > However vhost signaling reduction is needed as well. The patch I
> > > submitted a while ago showed both CPUs and BW improvement.
> > >
> > > Thanks
> > > Shirley
> >
> > Which patch was that?
>
> The patch was called "vhost: TX used buffer guest signal accumulation".
Yes, a somewhat similar idea.
> You suggested to split add_used_bufs and signal.
Exactly. And this is basically what this patch does.
> I am still thinking
> what's the best approach to cooperate guest (virtio_kick) and
> vhost(handle_tx), vhost(signaling) and guest (xmit callback) to reduce
> the overheads, so I haven't submit the new patch yet.
>
> Thanks
> Shirley
--
MST
next prev parent reply other threads:[~2011-02-02 10:48 UTC|newest]
Thread overview: 79+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <OFD293DCD2.7F0260F0-ON86257823.0061DC39-86257823.00743BB3@us.ibm.com>
[not found] ` <20110126151700.GA14113@redhat.com>
[not found] ` <1296153874.1640.27.camel@localhost.localdomain>
[not found] ` <20110127190031.GC5228@redhat.com>
[not found] ` <1296155340.1640.34.camel@localhost.localdomain>
[not found] ` <20110127193131.GD5228@redhat.com>
[not found] ` <1296157547.1640.45.camel@localhost.localdomain>
2011-01-27 20:05 ` Network performance with small packets Michael S. Tsirkin
2011-01-27 20:15 ` Shirley Ma
2011-01-28 18:29 ` Steve Dobbelstein
2011-01-28 22:51 ` Steve Dobbelstein
2011-02-01 15:52 ` [PATCHv2 dontapply] vhost-net tx tuning Michael S. Tsirkin
2011-02-01 23:07 ` Sridhar Samudrala
2011-02-01 23:27 ` Shirley Ma
2011-02-02 4:36 ` Michael S. Tsirkin
2011-01-27 21:02 ` Network performance with small packets David Miller
2011-01-27 21:30 ` Shirley Ma
2011-01-28 12:16 ` Michael S. Tsirkin
2011-02-01 0:24 ` Steve Dobbelstein
2011-02-01 1:30 ` Sridhar Samudrala
2011-02-01 5:56 ` Michael S. Tsirkin
2011-02-01 21:09 ` Shirley Ma
2011-02-01 21:24 ` Michael S. Tsirkin
2011-02-01 21:32 ` Shirley Ma
2011-02-01 21:42 ` Michael S. Tsirkin
2011-02-01 21:53 ` Shirley Ma
2011-02-01 21:56 ` Michael S. Tsirkin
2011-02-01 22:59 ` Shirley Ma
2011-02-02 4:40 ` Michael S. Tsirkin
2011-02-02 6:05 ` Shirley Ma
2011-02-02 6:19 ` Shirley Ma
2011-02-02 6:29 ` Michael S. Tsirkin
2011-02-02 7:14 ` Shirley Ma
2011-02-02 7:33 ` Shirley Ma
2011-02-02 10:49 ` Michael S. Tsirkin
2011-02-02 15:42 ` Shirley Ma
2011-02-02 15:48 ` Michael S. Tsirkin
2011-02-02 17:12 ` Shirley Ma
2011-02-02 18:20 ` Michael S. Tsirkin
2011-02-02 18:26 ` Shirley Ma
2011-02-02 10:48 ` Michael S. Tsirkin [this message]
2011-02-02 6:34 ` Krishna Kumar2
2011-02-02 7:03 ` Shirley Ma
2011-02-02 7:37 ` Krishna Kumar2
2011-02-02 10:48 ` Michael S. Tsirkin
2011-02-02 15:39 ` Shirley Ma
2011-02-02 15:47 ` Michael S. Tsirkin
2011-02-02 17:10 ` Shirley Ma
2011-02-02 17:32 ` Michael S. Tsirkin
2011-02-02 18:11 ` Shirley Ma
2011-02-02 18:27 ` Michael S. Tsirkin
2011-02-02 19:29 ` Shirley Ma
2011-02-02 20:17 ` Michael S. Tsirkin
2011-02-02 21:03 ` Shirley Ma
2011-02-02 21:20 ` Michael S. Tsirkin
2011-02-02 21:41 ` Shirley Ma
2011-02-03 5:59 ` Michael S. Tsirkin
2011-02-03 6:09 ` Shirley Ma
2011-02-03 6:16 ` Michael S. Tsirkin
2011-02-03 5:05 ` Shirley Ma
2011-02-03 6:13 ` Michael S. Tsirkin
2011-02-03 15:58 ` Shirley Ma
2011-02-03 16:20 ` Michael S. Tsirkin
2011-02-03 17:18 ` Shirley Ma
2011-02-01 5:54 ` Michael S. Tsirkin
2011-02-01 17:23 ` Michael S. Tsirkin
[not found] ` <1296590943.26937.797.camel@localhost.localdomain>
[not found] ` <20110201201715.GA30050@redhat.com>
2011-02-01 20:25 ` Shirley Ma
2011-02-01 21:21 ` Michael S. Tsirkin
2011-02-01 21:28 ` Shirley Ma
2011-02-01 21:41 ` Michael S. Tsirkin
2011-02-02 4:39 ` Krishna Kumar2
2011-02-02 4:42 ` Michael S. Tsirkin
2011-02-09 0:37 ` Rusty Russell
2011-02-09 0:53 ` Michael S. Tsirkin
2011-02-09 1:39 ` Rusty Russell
2011-02-09 1:55 ` Michael S. Tsirkin
2011-02-09 7:43 ` Stefan Hajnoczi
2011-03-08 21:57 ` Shirley Ma
2011-03-09 2:21 ` Andrew Theurer
2011-03-09 15:42 ` Shirley Ma
2011-03-10 1:49 ` Rusty Russell
2011-04-12 20:01 ` Michael S. Tsirkin
2011-04-14 11:28 ` Rusty Russell
2011-04-14 12:40 ` Michael S. Tsirkin
2011-04-14 16:03 ` Michael S. Tsirkin
2011-04-19 0:33 ` Rusty Russell
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