path: root/arch/x86
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authorLen Brown <len.brown@intel.com>2013-12-18 16:44:57 -0500
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-01-09 12:24:21 -0800
commit024df8e28d40f2e264bd502060008cf5c0946b61 (patch)
tree6ed0f9002e67f624dedf4a597ffc856b5e3c3bc0 /arch/x86
parent6b584e0dafc57e99fcd888ca94c506f294f7a36a (diff)
x86 idle: Repair large-server 50-watt idle-power regression
commit 40e2d7f9b5dae048789c64672bf3027fbb663ffa upstream. Linux 3.10 changed the timing of how thread_info->flags is touched: x86: Use generic idle loop (7d1a941731fabf27e5fb6edbebb79fe856edb4e5) This caused Intel NHM-EX and WSM-EX servers to experience a large number of immediate MONITOR/MWAIT break wakeups, which caused cpuidle to demote from deep C-states to shallow C-states, which caused these platforms to experience a significant increase in idle power. Note that this issue was already present before the commit above, however, it wasn't seen often enough to be noticed in power measurements. Here we extend an errata workaround from the Core2 EX "Dunnington" to extend to NHM-EX and WSM-EX, to prevent these immediate returns from MWAIT, reducing idle power on these platforms. While only acpi_idle ran on Dunnington, intel_idle may also run on these two newer systems. As of today, there are no other models that are known to need this tweak. Link: http://lkml.kernel.org/r/CAJvTdK=%2BaNN66mYpCGgbHGCHhYQAKx-vB0kJSWjVpsNb_hOAtQ@mail.gmail.com Signed-off-by: Len Brown <len.brown@intel.com> Link: http://lkml.kernel.org/r/baff264285f6e585df757d58b17788feabc68918.1387403066.git.len.brown@intel.com Signed-off-by: H. Peter Anvin <hpa@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'arch/x86')
1 files changed, 2 insertions, 1 deletions
diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c
index 9b0c441c03f..32d37d9a778 100644
--- a/arch/x86/kernel/cpu/intel.c
+++ b/arch/x86/kernel/cpu/intel.c
@@ -387,7 +387,8 @@ static void __cpuinit init_intel(struct cpuinfo_x86 *c)
set_cpu_cap(c, X86_FEATURE_PEBS);
- if (c->x86 == 6 && c->x86_model == 29 && cpu_has_clflush)
+ if (c->x86 == 6 && cpu_has_clflush &&
+ (c->x86_model == 29 || c->x86_model == 46 || c->x86_model == 47))
set_cpu_cap(c, X86_FEATURE_CLFLUSH_MONITOR);
#ifdef CONFIG_X86_64