Re: [patch] x86, tlb: switch cr3 in leave_mm() only when needed

[H. Peter Anvin]

On 03/22/2012 05:01 PM, Suresh Siddha wrote:
> 
> Agreed. Updated patch appended. Thanks.
> ---
> From: Suresh Siddha <suresh.b.siddha@xxxxxxxxx>
> Subject: x86, tlb: switch cr3 in leave_mm() only when needed
> 
> Currently leave_mm() unconditionally switches the cr3 to swapper_pg_dir.
> But there is no need to change the cr3, if we already left that mm.
> 
> intel_idle() for example calls leave_mm() on every deep c-state entry where
> the CPU flushes the TLB for us. Similarly flush_tlb_all() was also calling
> leave_mm() whenever the TLB is in LAZY state. Both these paths will be
> improved with this change.
> 
> Signed-off-by: Suresh Siddha <suresh.b.siddha@xxxxxxxxx>
> 

Looks great to me.  Linus, do you want this one later in the window if
it tests out OK between now and then, or is it too late?

	-hpa

-- 
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.

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