Subject: Re: [PATCH] powerpc: save trap number in bad_stack

From: Segher Boessenkool <[email-masked]>
Date: Fri, 20 Apr 2007 10:51:06 +0200

>>> +	u64 trap_save;			/* Used when bad stack is encountered */
>>
>> Can you put it elsewhere in the PACA (around less frequently used
>> bits) ? This is a pretty hot area of the PACA...
>
> It's only set in the bad_stack case though.
>
> You should put it after cpu_start, there's a bit hole there, and
> trap_save is readonly during normal operation, so it shouldn't be a
> performance hit.

That's not a performance hit compared to the current
state of the code, sure; but that "hot slot" could
be used for a hotter variable, instead.

Segher