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Commit ee1ca48f authored by Pallipadi, Venkatesh's avatar Pallipadi, Venkatesh Committed by Len Brown
Browse files

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: default avatarVenkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: default avatarLen Brown <len.brown@intel.com>
parent cd86a536

arch/x86/kernel/acpi/cstate.c

+13 −3
Original line number Diff line number Diff line
@@ -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);

drivers/acpi/processor_idle.c

+5 −2
Original line number Diff line number Diff line
@@ -512,7 +512,8 @@ static void acpi_processor_power_verify_c2(struct acpi_processor_cx *cx) 
static void acpi_processor_power_verify_c3(struct acpi_processor *pr,

					   struct acpi_processor_cx *cx)

{

	static int bm_check_flag;

	static int bm_check_flag = -1;

	static int bm_control_flag = -1;





	if (!cx->address)
@@ -542,12 +543,14 @@ static void acpi_processor_power_verify_c3(struct acpi_processor *pr, 
	}



	/* All the logic here assumes flags.bm_check is same across all CPUs */

	if (!bm_check_flag) {

	if (bm_check_flag == -1) {

		/* Determine whether bm_check is needed based on CPU  */

		acpi_processor_power_init_bm_check(&(pr->flags), pr->id);

		bm_check_flag = pr->flags.bm_check;

		bm_control_flag = pr->flags.bm_control;

	} else {

		pr->flags.bm_check = bm_check_flag;

		pr->flags.bm_control = bm_control_flag;

	}



	if (pr->flags.bm_check) {