path: root/arch/x86/include
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authorBorislav Petkov <borislav.petkov@amd.com>2011-01-20 15:42:52 +0100
committerH. Peter Anvin <hpa@linux.intel.com>2011-01-21 18:14:54 -0800
commit93789b32dbf355e70f18b17a82e8661677a7f7fb (patch)
tree551a937a1f236118fd149cbbcc635ef283a7a94c /arch/x86/include
parentf21bbec9ffcaf73e99938209e52b757d93f9133b (diff)
x86, hotplug: Fix powersavings with offlined cores on AMD
ea53069231f9317062910d6e772cca4ce93de8c8 made a CPU use monitor/mwait when offline. This is not the optimal choice for AMD wrt to powersavings and we'd prefer our cores to halt (i.e. enter C1) instead. For this, the same selection whether to use monitor/mwait has to be used as when we select the idle routine for the machine. With this patch, offlining cores 1-5 on a X6 machine allows core0 to boost again. [ hpa: putting this in urgent since it is a (power) regression fix ] Reported-by: Andreas Herrmann <andreas.herrmann3@amd.com> Cc: stable@kernel.org # 37.x Cc: H. Peter Anvin <hpa@linux.intel.com> Cc: Arjan van de Ven <arjan@linux.intel.com> Cc: Len Brown <lenb@kernel.org> Cc: Venkatesh Pallipadi <venki@google.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.hl> Signed-off-by: Borislav Petkov <borislav.petkov@amd.com> LKML-Reference: <1295534572-10730-1-git-send-email-bp@amd64.org> Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Diffstat (limited to 'arch/x86/include')
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/x86/include/asm/cpu.h b/arch/x86/include/asm/cpu.h
index 4fab24de26b..6e6e7558e70 100644
--- a/arch/x86/include/asm/cpu.h
+++ b/arch/x86/include/asm/cpu.h
@@ -32,5 +32,6 @@ extern void arch_unregister_cpu(int);
DECLARE_PER_CPU(int, cpu_state);
+int __cpuinit mwait_usable(const struct cpuinfo_x86 *);
#endif /* _ASM_X86_CPU_H */