From 25b8b7b8813f849c132db597510c4d61c47566fa Mon Sep 17 00:00:00 2001 From: Duncan Laurie Date: Fri, 19 Apr 2013 10:02:23 -0700 Subject: haswell: Put each logical processor in its own P-state domain The recommendation from Intel is to report each core as a separate logical domain in the _PSD table. This goes against the recommendation in the ACPI specification because all of these cores are on the same package and share a VR so they will do voltage transitions together. The reasoning is that with a larger number of logical processors the P-state often ramps too quickly resulting in higher power consumption. By exposing each core as a separate domain the OS can manage them individually allowing the socket to select the optimum frequency. $ cat /sys/firmware/acpi/tables/SSDT > /tmp/SSDT $ iasl -d /tmp/SSDT Processor (\_PR.CPU0, 0x00, 0x00000000, 0x00) { Name (_PSD, Package (0x01) { Package (0x05) { 0x05, 0x00, 0x00000000, 0x000000FE, 0x00000001 } }) } Processor (\_PR.CPU1, 0x01, 0x00000000, 0x00) { Name (_PSD, Package (0x01) { Package (0x05) { 0x05, 0x00, 0x00000001, 0x000000FE, 0x00000001 } }) } Processor (\_PR.CPU2, 0x02, 0x00000000, 0x00) { Name (_PSD, Package (0x01) { Package (0x05) { 0x05, 0x00, 0x00000002, 0x000000FE, 0x00000001 } }) } Processor (\_PR.CPU3, 0x03, 0x00000000, 0x00) { Name (_PSD, Package (0x01) { Package (0x05) { 0x05, 0x00, 0x00000003, 0x000000FE, 0x00000001 } }) } Change-Id: I5ef41b6ead4d88e9ba117003293dbc629c376803 Signed-off-by: Duncan Laurie Reviewed-on: https://gerrit.chromium.org/gerrit/48662 Reviewed-by: Aaron Durbin Reviewed-on: http://review.coreboot.org/4130 Tested-by: build bot (Jenkins) Reviewed-by: Ronald G. Minnich --- src/cpu/intel/haswell/acpi.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/src/cpu/intel/haswell/acpi.c b/src/cpu/intel/haswell/acpi.c index a4d9cd9292..9e10c7527a 100644 --- a/src/cpu/intel/haswell/acpi.c +++ b/src/cpu/intel/haswell/acpi.c @@ -254,7 +254,7 @@ static int generate_P_state_entries(int core, int cores_per_package) len += acpigen_write_PPC_NVS(); /* Write PSD indicating configured coordination type */ - len += acpigen_write_PSD_package(core, cores_per_package, coord_type); + len += acpigen_write_PSD_package(core, 1, coord_type); /* Add P-state entries in _PSS table */ len += acpigen_write_name("_PSS"); @@ -346,7 +346,7 @@ void generate_cpu_entries(void) /* Generate P-state tables */ len_pr += generate_P_state_entries( - cpuID-1, cores_per_package); + coreID-1, cores_per_package); /* Generate C-state tables */ len_pr += generate_C_state_entries(); -- cgit v1.2.3