Re: [ANNOUNCE] kvm-guest-drivers-windows-2

Anthony Liguori
2008-05-14T17:50:01Z

Dor Laor wrote:
> On Wed, 2008-05-14 at 17:49 +0200, Tomasz Chmielewski wrote:
>
>> Dor Laor schrieb:
>>
>> (...)
>>
>>
>>>> - PV Windows (network driver)
>>>>
>>> About 700Mb+-, there is currently extra copy that we need to omit.
>>> Thanks for Anthony, we just have to change the driver.
>>>
>>>
>>>> - non-PV Windows
>>>>
>>> What do you mean? Other fully emulated nics like e1000?
>>> It does not perform as pv but depending on the guest it can do up to
>>> 600Mb+-.
>>>
>> Just generally, how Windows PV drivers help to improve network performance.
>>
>> So, a PV network driver can do about 700Mb/s, and an emulated NIC can do about
>> 600 Mb/s, Windows guest to host?
>>
>> That would be about 20% improvement?
>>

FWIW, virtio-net is much better with my patches applied. The difference
between the e1000 and virtio-net is that e1000 consumes almost twice as
much CPU as virtio-net so in my testing, the performance improvement
with virtio-net is about 2x. We were loosing about 20-30% throughput
because of the delays in handling incoming packets.

Regards,

Anthony LIguori

>>
>
> It's work in progress, doing zero copy in the guest, adding TSO, using
> virtio'd tap will drastically boot performance. There is no reason the
> performance won't match Linux guest.
> Also I don't exactly remember the numbers but the gain in the tx pass is
> grater.
>
>
>
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