Re: accessed/dirty bit handler tuning

[Zoltan Menyhart <Zoltan.Menyhart@bull.net>]

Christoph Lameter wrote:

> Could you measure the effect that this has? We seem to be getting into 
> some special processor behavior here.

Telling the truth: I cannot measure it.

The architecture ia64 defines some hints which *may* increase the performance.

If you have a sequence that does not cost a penny and may run faster...
If you have a shorter and somewhat faster sequence because of the elimination
of "cmp" that had to wait the completion the "cmpxchg"...
... why not?

> The last that I heard about nta was that it just skips the marking of a 
> cacheline as recent. Thus the cacheline will be a more likely candidate to 
> be evicted from the caches. Are you sure that the processors can bypass 
> the L1D and L3?

Please refer to e.g. the I2 Proc. Ref. Man. for SW Dev. & Opt. - may 2004
table 5-4 on page 41.

Thanks,

Zoltan