[Http-crcsync] Fwd: Re: [Fwd: Re: Google summer of code : 'web pages over rsync']

[Rusty Russell]

On Mon, 22 Jun 2009 07:30:32 am Alex Wulms wrote:
> Hi,
>
> I have analyzed my logs. Here are the statistics:
> Number of responses containing some delta-data: 233
> Average size of response body: 3191 bytes
> Number of responses with a body smaller then 3000 bytes: 131
> Number of responses with a body smaller then 2500 bytes: 127
>
> I currently don't have statistics on the response header size. I realize
> that the body+header together should be less then 3000 bytes. That is why I
> also included the number of responses with a body smaller then 2500 bytes,
> assuming header will often be smaller then 500 bytes.

The critical number is actually 1408 * 2 (modern TCP uses timestamps, making 
it 12 bytes of option + 20 byte TCP hdr + 20 byte IP hdr, leaving 1408 bytes 
for data).

So you have 2416 bytes *total*.   I don't know we can do much about this on 
the response side except make our protocol tight.  We should, however, 
consider it on the request side, where we can control the number of blocks 
(ie. signatures)

Cheers,
Rusty.