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authorBorislav Petkov <borislav.petkov@amd.com>2011-01-20 09:42:52 -0500
committerH. Peter Anvin <hpa@linux.intel.com>2011-01-21 21:14:54 -0500
commit93789b32dbf355e70f18b17a82e8661677a7f7fb (patch)
tree551a937a1f236118fd149cbbcc635ef283a7a94c /arch/x86/kernel/smpboot.c
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/kernel/smpboot.c')
-rw-r--r--arch/x86/kernel/smpboot.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 763df77343dd..0cbe8c0b35ed 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -1402,8 +1402,9 @@ static inline void mwait_play_dead(void)
1402 unsigned int highest_subcstate = 0; 1402 unsigned int highest_subcstate = 0;
1403 int i; 1403 int i;
1404 void *mwait_ptr; 1404 void *mwait_ptr;
1405 struct cpuinfo_x86 *c = __this_cpu_ptr(&cpu_info);
1405 1406
1406 if (!cpu_has(__this_cpu_ptr(&cpu_info), X86_FEATURE_MWAIT)) 1407 if (!(cpu_has(c, X86_FEATURE_MWAIT) && mwait_usable(c)))
1407 return; 1408 return;
1408 if (!cpu_has(__this_cpu_ptr(&cpu_info), X86_FEATURE_CLFLSH)) 1409 if (!cpu_has(__this_cpu_ptr(&cpu_info), X86_FEATURE_CLFLSH))
1409 return; 1410 return;