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

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Date:	Sun, 24 Feb 2008 08:27:30 +0100
From:	Roger While <simrw@...-basis.de>
To:	linux-kernel@...r.kernel.org
Cc:	suresh.b.siddha@...el.com
Subject: Re: [patch 1/2] x86,fpu: split FPU state from task struct


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));  ?

Roger


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