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authorVenki Pallipadi <venkatesh.pallipadi@intel.com>2008-01-30 07:32:01 -0500
committerIngo Molnar <mingo@elte.hu>2008-01-30 07:32:01 -0500
commitbde6f5f59c2b2b48a7a849c129d5b48838fe77ee (patch)
tree4fa3befdfa227db56770a0dc85b8fc18be232f70 /include/asm-x86/mmu.h
parent7d409d6057c7244f8757ce15245f6df27271be0c (diff)
x86: voluntary leave_mm before entering ACPI C3
Aviod TLB flush IPIs during C3 states by voluntary leave_mm() before entering C3. The performance impact of TLB flush on C3 should not be significant with respect to C3 wakeup latency. Also, CPUs tend to flush TLB in hardware while in C3 anyways. On a 8 logical CPU system, running make -j2, the number of tlbflush IPIs goes down from 40 per second to ~ 0. Total number of interrupts during the run of this workload was ~1200 per second, which makes it ~3% savings in wakeups. There was no measurable performance or power impact however. [ akpm@linux-foundation.org: symbol export fixes. ] Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'include/asm-x86/mmu.h')
-rw-r--r--include/asm-x86/mmu.h8
1 files changed, 8 insertions, 0 deletions
diff --git a/include/asm-x86/mmu.h b/include/asm-x86/mmu.h
index 3f922c8e1c88..efa962c38897 100644
--- a/include/asm-x86/mmu.h
+++ b/include/asm-x86/mmu.h
@@ -20,4 +20,12 @@ typedef struct {
20 void *vdso; 20 void *vdso;
21} mm_context_t; 21} mm_context_t;
22 22
23#ifdef CONFIG_SMP
24void leave_mm(int cpu);
25#else
26static inline void leave_mm(int cpu)
27{
28}
29#endif
30
23#endif /* _ASM_X86_MMU_H */ 31#endif /* _ASM_X86_MMU_H */