Re: 2.6.0-test3-mm1: scheduling while atomic (ext3?)

[Alan Cox <alan@lxorguk.ukuu.org.uk>]

On Mer, 2003-08-13 at 16:32, Andi Kleen wrote:
> The AMD slides assume all very big data sets ;-)
> 
> I would recommend to remove it.

I'll do some timings when I get a moment - the prefetching mmx copy
was a win (and faster than the others for small data as well as large
on the K7-550 (really a K7 not "Athlon" 8)) way back when.

> > What else checks the 3Dnow bit ?
> 
> Nothing in kernel AFAIK, but it's possible that it is used by user space
> reading /proc/cpuinfo.

DaveJ and your docs are right on 3dnow it turns out so sorry about that
and ignore me on prefetchw, its just the prefetch side thats 3 way.

> BTW we saw it mainly in the x86-64 copy_*_user and csum_copy_* functions
> which do also prefetches. LTP would sometimes trigger it when it tests
> how the kernel behaves with invalid addresses. But it happened very
> rarely in the dcache hash too. But still it's hard to trigger, the
> linked list one is very hard to hit. I tried to reproduce it in user space,
> but failed. The LTP one is much easier, but still not that common.

Thanks