From: Venki Pallipadi Date: Wed, 30 Jan 2008 12:32:01 +0000 (+0100) Subject: x86: voluntary leave_mm before entering ACPI C3 X-Git-Tag: v2.6.25-rc1~1143^2~488 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=bde6f5f59c2b2b48a7a849c129d5b48838fe77ee;p=pandora-kernel.git 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 Signed-off-by: Ingo Molnar Signed-off-by: Thomas Gleixner --- Reading git-diff-tree failed