Re: [PATCH 0/15] KVM: optimize for MMIO handled

Takuya Yoshikawa
2011-06-08T03:44:56Z

On Wed, 08 Jun 2011 11:32:12 +0800
Xiao Guangrong <xiaoguangrong@cn.fujitsu.com> wrote:

> On 06/08/2011 11:25 AM, Xiao Guangrong wrote:
> > On 06/08/2011 11:11 AM, Takuya Yoshikawa wrote:
> >> On Tue, 07 Jun 2011 20:58:06 +0800
> >> Xiao Guangrong <xiaoguangrong@cn.fujitsu.com> wrote:
> >>
> >>> The performance test result:
> >>>
> >>> Netperf (TCP_RR):
> >>> ===========================
> >>> ept is enabled:
> >>>
> >>> Before After
> >>> 1st 709.58 734.60
> >>> 2nd 715.40 723.75
> >>> 3rd 713.45 724.22
> >>>
> >>> ept=0 bypass_guest_pf=0:
> >>>
> >>> Before After
> >>> 1st 706.10 709.63
> >>> 2nd 709.38 715.80
> >>> 3rd 695.90 710.70
> >>>
> >>
> >> In what condition, does TCP_RR perform so bad?
> >>
> >> On 1Gbps network, directly connecting two Intel servers,
> >> I got 20 times better result before.
> >>
> >> Even when I used a KVM guest as the netperf client,
> >> I got more than 10 times better result.
> >>
> >
> > Um, which case did you test? ept = 1 or ept=0 bypass_guest_pf=0 or both?
> >

ept = 1 only.

> >> Could you tell me a bit more details of your test?
> >>
> >
> > Sure, KVM guest is the client, and it uses e1000 NIC, and uses NAT
> > network connect to the netperf server, the bandwidth of our network
> > is 100M.
> >

I see the reason, thank you!

I used virtio-net and you used e1000.
You are using e1000 to see the MMIO performance change, right?

Takuya

>
> And this is my test script:
>
> #!/bin/sh
>
> echo 3 > /proc/sys/vm/drop_caches
> ./netperf -H $HOST_NAME -p $PORT -t TCP_RR -l 60
>