Re: [hybi] Upgrade Mechanism and HasMat (was Re: Extensibility mechanisms?)

[Dave Cridland <[e-mail]>]

On Thu Jul 22 13:13:17 2010, Willy Tarreau wrote:
> The only fear I have right now with the nonce as defined by the WS  
> draft
> is that it makes use of MD5 which comes with a cost. I know at  
> least one
> site dealing with more than 300k concurrent connections at a rate  
> between
> 12 and 18k per second (long polling right now), and I think that  
> computing
> MD5 hashes can significantly impact performance at these rates. If  
> the
> goal is to ensure the response header depends on the request  
> header, we
> may reliably make use of cheaper algorithms.

I'd assume that an actual server can do faster than my cheap  
workstation:

$ openssl speed md5
Doing md5 for 3s on 16 size blocks: 7765276 md5's in 3.00s
Doing md5 for 3s on 64 size blocks: 6086328 md5's in 3.00s
Doing md5 for 3s on 256 size blocks: 3674140 md5's in 3.00s
Doing md5 for 3s on 1024 size blocks: 1420165 md5's in 3.00s
Doing md5 for 3s on 8192 size blocks: 212112 md5's in 3.00s

FWIW, SHA-1 is only slightly slower. If you had 300k all join at  
once, then it still seems to be this would be a drop in the ocean in  
terms of loading.

Dave.
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