Subject: Re: [RFC PATCH v8 00/16] Provide a zero-copy method on KVM
 virtio-net.
From: Shirley Ma <mashirle@us.ibm.com>
To: Avi Kivity <avi@redhat.com>
Cc: xiaohui.xin@intel.com, netdev@vger.kernel.org, kvm@vger.kernel.org,
        linux-kernel@vger.kernel.org, mst@redhat.com, mingo@elte.hu,
        davem@davemloft.net, herbert@gondor.hengli.com.au,
        jdike@linux.intel.com
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Date: Tue, 10 Aug 2010 20:28:02 -0700
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Hello Avi,

On Mon, 2010-08-02 at 19:32 +0300, Avi Kivity wrote:
> When are you seeing gup_fast() fall back to gup()?  It should be at
> most 
> once per page (when a guest starts up none of its pages are mapped,
> it 
> faults them in on demand). 

netperf/netserver latency results are pretty good for message size
between 1 bytes and 512 bytes when I have 64 bytes small copy.

However if I don't have any small copy , the ping RTT time is
unreasonable huge. Since we think it's better to have small message with
copy, so there will be no issue.

Thanks
Shirley

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