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authorPallipadi, Venkatesh <venkatesh.pallipadi@intel.com>2009-05-21 17:09:10 -0700
committerLen Brown <len.brown@intel.com>2009-05-27 21:57:30 -0400
commitee1ca48fae7e575d5e399d4fdcfe0afc1212a64c (patch)
treed2d8c9bd4a806e603ba272a7f71644af1fdb16a3 /arch
parentcd86a536c81e9300d984327517548ca0652eebf9 (diff)
downloadop-kernel-dev-ee1ca48fae7e575d5e399d4fdcfe0afc1212a64c.zip
op-kernel-dev-ee1ca48fae7e575d5e399d4fdcfe0afc1212a64c.tar.gz
ACPI: Disable ARB_DISABLE on platforms where it is not needed
ARB_DISABLE is a NOP on all of the recent Intel platforms. For such platforms, reduce contention on c3_lock by skipping the fake ARB_DISABLE. Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com> Signed-off-by: Len Brown <len.brown@intel.com>
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/kernel/acpi/cstate.c16
1 files changed, 13 insertions, 3 deletions
diff --git a/arch/x86/kernel/acpi/cstate.c b/arch/x86/kernel/acpi/cstate.c
index bbbe4bb..8c44c23 100644
--- a/arch/x86/kernel/acpi/cstate.c
+++ b/arch/x86/kernel/acpi/cstate.c
@@ -34,12 +34,22 @@ void acpi_processor_power_init_bm_check(struct acpi_processor_flags *flags,
flags->bm_check = 1;
else if (c->x86_vendor == X86_VENDOR_INTEL) {
/*
- * Today all CPUs that support C3 share cache.
- * TBD: This needs to look at cache shared map, once
- * multi-core detection patch makes to the base.
+ * Today all MP CPUs that support C3 share cache.
+ * And caches should not be flushed by software while
+ * entering C3 type state.
*/
flags->bm_check = 1;
}
+
+ /*
+ * On all recent Intel platforms, ARB_DISABLE is a nop.
+ * So, set bm_control to zero to indicate that ARB_DISABLE
+ * is not required while entering C3 type state on
+ * P4, Core and beyond CPUs
+ */
+ if (c->x86_vendor == X86_VENDOR_INTEL &&
+ (c->x86 > 0x6 || (c->x86 == 6 && c->x86_model >= 14)))
+ flags->bm_control = 0;
}
EXPORT_SYMBOL(acpi_processor_power_init_bm_check);
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