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Re: Asynchronous crypto layer.

To: Eugene Surovegin <ebs@xxxxxxxxxxx>
Subject: Re: Asynchronous crypto layer.
From: Evgeniy Polyakov <johnpol@xxxxxxxxxxx>
Date: Sun, 31 Oct 2004 01:24:23 +0400
Cc: hadi@xxxxxxxxxx, netdev@xxxxxxxxxxx, cryptoapi@xxxxxxxxxxxxxx
In-reply-to: <20041030205630.GD6256@xxxxxxxxxxxxxxxx>
Organization: MIPT
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On Sat, 30 Oct 2004 13:56:31 -0700
Eugene Surovegin <ebs@xxxxxxxxxxx> wrote:

> On Sun, Oct 31, 2004 at 01:04:15AM +0400, Evgeniy Polyakov wrote:
> > On Sat, 30 Oct 2004 13:35:50 -0700
> > Eugene Surovegin <ebs@xxxxxxxxxxx> wrote:
> > 
> > > On Fri, Oct 29, 2004 at 06:06:52PM +0400, Evgeniy Polyakov wrote:
> > > > If we have a hardware accelerator chip, than we _already_ have 
> > > > improvements 
> > > > with even the worst async crypto layer, since software and hardware 
> > > > will work in parrallel.
> > > 
> > > This is not true. 
> > > 
> > > For example, if chip request setup and PCI transfer takes more than 
> > > just using sw implementation. This is reality for AES and short 
> > > packets.
> > 
> > You have dataflow of packets, if invoce expenses take less time
> > then you will win.
> 
> Yes, but as I said for short packets, AES and fast box for example 
> this might not be true.
> 
> > More than 1kbyte of data to be encrypted already beats time
> > need for software encryption on 266 mhz.
> 
> OK, what about 64 byte packets? I'm not saying hw crypto is useless, 
> what I'm saying is it's not that obvious that having hw crypto will 
> help in _all_ situations.

Sure.
For such cases I offered "rate" or "speed" parameter in my first e-mail, 
but it can be implicitly implemented by queue length.
With 1 big datflow of packets with high priority and little dataflow of
packets with little priority if we will catch high priority packets by SW
and thus can have situation when we will _never_ catch low-priority packets, 
with even very slow HW we can route all those low-priority packets into it, 
at least they will be processed sometimes...

> > And what about asynchronous crypto? 
> 
> Asynchronous? Never heard of it. Did you mean asymmetric?

:)
 
> If yes, ok, I _think_ hw crypto will help, provided we have kernel API 
> for such stuff.
> 
> --
> Eugene


        Evgeniy Polyakov

Only failure makes us experts. -- Theo de Raadt

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