x86, tlb: Switch cr3 in leave_mm() only when needed

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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@intel.com>
Link: http://lkml.kernel.org/r/1332460885.16101.147.camel@sbsiddha-desk.sc.intel.com
Signed-off-by: H. Peter Anvin <hpa@zytor.com>

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Suresh Siddha 2012-03-22 17:01:25 -07:00 • committed by H. Peter Anvin

parent 722bc6b167

commit a6fca40f1d

1 changed files with 5 additions and 3 deletions

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arch/x86/mm/tlb.c

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