Re: [patch 1/2] x86,fpu: split FPU state from task struct

["Siddha, Suresh B" <suresh.b.siddha@intel.com>]

On Sun, Feb 24, 2008 at 08:27:30AM +0100, Roger While wrote:
> 
> On Sat, Feb 23, 2008 at 06:34:38PM -0800, Suresh Siddha wrote:
> > Split the FPU save area from the task struct. This allows easy migration
> > of FPU context, and it's generally cleaner. It also allows the following
> > two optimizations:
> >
> > 1) only allocate when the application actually uses FPU, so in the first
> > lazy FPU trap. This could save memory for non-fpu using apps. Next patch
> > does this lazy allocation.
> >
> > 2) allocate the right size for the actual cpu rather than 512 bytes 
> always.
> > Patches enabling xsave/xrstor support (coming shortly) will take advantage
> > of this.
> 
> >  	if (next_p->fpu_counter>5)
> > -		prefetch(&next->i387.fxsave);
> > +		prefetch(FXSAVE(next_p));
> 
> Shouldn't that be  prefetch(FXSAVE(next));  ?

No. 'next_p' which is the task_struct is what FXSAVE macro takes.

thanks,
suresh