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From: "Chen, Kenneth W" <kenneth.w.chen@intel.com>
To: "'Keith Owens'" <kaos@ocs.com.au>, "Ingo Molnar" <mingo@elte.hu>
Cc: <David.Mosberger@acm.org>, "Andrew Morton" <akpm@osdl.org>,
       <linux-kernel@vger.kernel.org>, <linux-ia64@vger.kernel.org>
Subject: RE: Add prefetch switch stack hook in scheduler function 
Date: Fri, 29 Jul 2005 01:08:48 -0700
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Keith Owens wrote on Friday, July 29, 2005 12:38 AM
> BTW, for ia64 you may as well prefetch pt_regs, that is also quite
> large.
> 
> #define MIN_KERNEL_STACK_FOOTPRINT (IA64_SWITCH_STACK_SIZE + IA64_PT_REGS_SIZE)

This has to be carefully done, because you really don't want to overwhelm
number of outstanding L2 cache misses.  It only has a limited amount of
queue and once that is filled, cpu get into L2 recirculate state.  And that
is going to be very painful because it translate into cpu stall cycles.