From: David Miller <davem@davemloft.net>
To: mst@redhat.com
Cc: yvugenfi@redhat.com, kvm@vger.kernel.org, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org,
virtualization@lists.linux-foundation.org,
herbert@gondor.hengli.com.au
Subject: Re: [PATCH] virtio_net: introduce VIRTIO_NET_HDR_F_DATA_VALID
Date: Sat, 11 Jun 2011 15:58:02 -0700 (PDT) [thread overview]
Message-ID: <20110611.155802.495936379311916892.davem__49496.077912818$1307833151$gmane$org@davemloft.net> (raw)
In-Reply-To: <20110610112828.GA21037@redhat.com>
From: "Michael S. Tsirkin" <mst@redhat.com>
Date: Fri, 10 Jun 2011 14:28:28 +0300
> On Fri, Jun 10, 2011 at 06:56:17PM +0800, Jason Wang wrote:
>> There's no need for the guest to validate the checksum if it have been
>> validated by host nics. So this patch introduces a new flag -
>> VIRTIO_NET_HDR_F_DATA_VALID which is used to bypass the checksum
>> examing in guest. The backend (tap/macvtap) may set this flag when
>> met skbs with CHECKSUM_UNNECESSARY to save cpu utilization.
>>
>> No feature negotiation is needed as old driver just ignore this flag.
>
> This wasn't required by the spec, but maybe it should be.
>
>> Iperf shows 12%-30% performance improvement for UDP traffic. For TCP,
>> when gro is on no difference as it produces skb with partial
>> checksum. But when gro is disabled, 20% or even higher improvement
>> could be measured by netperf.
>>
>> Signed-off-by: Jason Wang <jasowang@redhat.com>
>
>
> Acked-by: Michael S. Tsirkin <mst@redhat.com>
Applied to net-next-2.6
next prev parent reply other threads:[~2011-06-11 22:58 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-06-10 10:56 [PATCH] virtio_net: introduce VIRTIO_NET_HDR_F_DATA_VALID Jason Wang
2011-06-10 11:28 ` Michael S. Tsirkin
2011-06-11 22:58 ` David Miller
2011-06-11 22:58 ` David Miller [this message]
2011-06-10 11:28 ` Michael S. Tsirkin
2011-06-10 10:56 Jason Wang
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