Changing default module options

[Zhu Yi]

On Wed, 2010-03-24 at 17:49 +0800, Stanislaw Gruszka wrote:
> On Wed, Mar 24, 2010 at 09:30:24AM +0800, Zhu Yi wrote:
> > On Tue, 2010-03-23 at 19:03 +0800, Stanislaw Gruszka wrote:
> > > Ah, ok. So only additional cost with "paged Rx" and swcrypto is a
> > > memcpy, which is theoretically rather small cost compared with doing
> > > tx/rx cryptography in main cpu.
> > >       
> > > So, what about turn on swcrypto by default upstream? 
> > 
> > hwcrypto offloads cryptography to the device. It saves host CPU cycles
> > so it's a good thing to do. 
> 
> Have you did benchmarking ? :-P

Yeah, I remembered I did it on 3945 sometime (long) ago. It was about 5%
CPU cycles save for CCMP/AES. It should also save the system power. But
I forgot the number.

> Question is how swcrypto=1 hurts, does we have any valuable data
> for that?
> 
> > The bug #519154 doesn't affect most people
> > and only for 4965.
> Don't like logic in that sentence.

If I read the corresponding kernel bugzilla report correctly, this only
affect to small portion of people.

> >  #556990 doesn't look like swcrypto related, need to
> > do more investigation. 
> 
> User reported swcrypto=1 helps with it on 2.6.32.

See my comments in the bug. The issues should be both fixed in upstream.

> > So I don't think we should use swcrypto=1 by
> > default in upstream. Users are free to do so in their /etc/modprobe.d
> > though.
> 
> I think many users don't know about, and just live whit random crashes
> from time to time, or switch back to windows :-/

The windows driver also crashes. They just don't tell you about it. Do
you want a "feature" like that in Linux? ;-)

Thanks,
-yi