Re: [hybi] hum #3: Message

[Douglas Otis <[e-mail]>]

On 8/5/10 11:42 AM, John Tamplin wrote:
> On Thu, Aug 5, 2010 at 2:22 PM, Ian Hickson <[e-mail] 
> <mailto:[e-mail]>> wrote:
>
>     When transfering large blocks of data, chunking is quite
>     inefficient. This
>     means that we'd need to make sure that the fixed width field is at
>     least
>     long enough to handle large chunks of data.
>
>     At terabit Ethernet speeds, 32 bits is not enough since you could
>     transfer
>     that much in mere seconds, so presumably we'll use 64 bits.
>
>     Do we really want a length that long?
>
>
> Let's assume the most recent proposal, which is a 4-byte header 
> including a 2-byte length field.  So, if you need to send a message of 
> 2^32 bytes, it will be sent as a 65538 frames, incurring an overhead 
> of 262152 bytes for header overhead, or a total of 4295229448 bytes 
> with .0006% overhead over the payload data.  It is true that this is 
> higher overhead than a single large frame with a variable-length 
> length field, but it hardly rises to "quite inefficient".  Also, other 
> reasons have been given for why you don't want to send a single frame 
> that long anyway, and for why you don't want to have to keep an 
> arbitrarily large buffer in the sender just so you can count the bytes 
> of the entire message before you send it.
+1

-Doug