linux-kernel - Re: [PATCH net-next V2 0/3] rx busy polling support for virtio-net

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Date:	Mon, 21 Jul 2014 11:15:00 +0800
From:	Jason Wang <jasowang@...hat.com>
To:	"Michael S. Tsirkin" <mst@...hat.com>
CC:	rusty@...tcorp.com.au, virtualization@...ts.linux-foundation.org,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH net-next V2 0/3] rx busy polling support for virtio-net

On 07/21/2014 04:34 AM, Michael S. Tsirkin wrote:
> On Wed, Jul 16, 2014 at 02:21:44PM +0800, Jason Wang wrote:
>> Hi all:
>>
>> This series introduces the support for rx busy polling support. This
>> was useful for reduing the latency for a kvm guest. Patch 1-2
>> introduces helpers which is used for rx busy polling. Patch 3
>> implement the main function.
>>
>> Test was done between a kvm guest and an external host. Two hosts were
>> connected through 40gb mlx4 cards. With both busy_poll and busy_read are
>> set to 50 in guest, 1 byte netperf tcp_rr shows 116% improvement:
>> transaction rate was increased from 9151.94 to 19787.37.
>>
>> Changes from V1:
>> - split the patch info smaller ones
>> - add more details about test setup/configuration
>>
>> Please review.
> Generally I think we should let host know we are polling.
> For example, kick the rq or something. Or maybe add another
> io address.

Yes, I'm also working on busy polling for tun and vhost which may also
help here.
> Something like this would need a new feature flag though, so I'm fine
> with just polling in guest until that is available.

Yes.
>
>> Jason Wang (3):
>>   virtio-net: introduce helpers to enable and disable all NAPIs
>>   virtio-net: introduce virtnet_receive()
>>   virtio-net: rx busy polling support
>>
>>  drivers/net/virtio_net.c | 234 ++++++++++++++++++++++++++++++++++++++++++++---
>>  1 file changed, 221 insertions(+), 13 deletions(-)
>>
>> -- 
>> 1.8.3.1
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