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authorDuncan Laurie <dlaurie@chromium.org>2013-04-19 10:02:23 -0700
committerAlexandru Gagniuc <mr.nuke.me@gmail.com>2013-11-24 05:34:25 +0100
commit25b8b7b8813f849c132db597510c4d61c47566fa (patch)
tree0fd3218e0c3314338b670d604d3cb61c8f9b88c0 /Makefile
parent77647b33cf33e882a0a21f7d46c42b54945e8045 (diff)
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 <dlaurie@chromium.org> Reviewed-on: https://gerrit.chromium.org/gerrit/48662 Reviewed-by: Aaron Durbin <adurbin@chromium.org> Reviewed-on: http://review.coreboot.org/4130 Tested-by: build bot (Jenkins) Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>
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