• Venki Pallipadi's avatar
    x86: voluntary leave_mm before entering ACPI C3 · bde6f5f5
    Venki Pallipadi authored
    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: default avatarVenkatesh Pallipadi <venkatesh.pallipadi@intel.com>
    Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
    Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
    bde6f5f5
acpi.h 3.99 KB