Huang Rui b466bdb614 x86/asm/delay: Introduce an MWAITX-based delay with a configurable timer ...

MWAITX can enable a timer and a corresponding timer value
specified in SW P0 clocks. The SW P0 frequency is the same as
TSC. The timer provides an upper bound on how long the
instruction waits before exiting.

This way, a delay function in the kernel can leverage that
MWAITX timer of MWAITX.

When a CPU core executes MWAITX, it will be quiesced in a
waiting phase, diminishing its power consumption. This way, we
can save power in comparison to our default TSC-based delays.

A simple test shows that:

	$ cat /sys/bus/pci/devices/0000\:00\:18.4/hwmon/hwmon0/power1_acc
	$ sleep 10000s
	$ cat /sys/bus/pci/devices/0000\:00\:18.4/hwmon/hwmon0/power1_acc

Results:

	* TSC-based default delay:      485115 uWatts average power
	* MWAITX-based delay:           252738 uWatts average power

Thus, that's about 240 milliWatts less power consumption. The
test method relies on the support of AMD CPU accumulated power
algorithm in fam15h_power for which patches are forthcoming.

Suggested-by: Andy Lutomirski <luto@amacapital.net>
Suggested-by: Borislav Petkov <bp@suse.de>
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Huang Rui <ray.huang@amd.com>
[ Fix delay truncation. ]
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Aaron Lu <aaron.lu@intel.com>
Cc: Andreas Herrmann <herrmann.der.user@gmail.com>
Cc: Aravind Gopalakrishnan <Aravind.Gopalakrishnan@amd.com>
Cc: Fengguang Wu <fengguang.wu@intel.com>
Cc: Frédéric Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Hector Marco-Gisbert <hecmargi@upv.es>
Cc: Jacob Shin <jacob.w.shin@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Len Brown <lenb@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Li <tony.li@amd.com>
Link: http://lkml.kernel.org/r/1438744732-1459-3-git-send-email-ray.huang@amd.com
Link: http://lkml.kernel.org/r/1439201994-28067-4-git-send-email-bp@alien8.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>

2015-08-22 14:52:16 +02:00

..

.gitignore

x86: Gitignore: arch/x86/lib/inat-tables.c

2009-11-04 13:11:28 +01:00

atomic64_32.c

x86: Adjust asm constraints in atomic64 wrappers

2012-01-20 17:29:31 -08:00

atomic64_386_32.S

x86/debug: Remove perpetually broken, unmaintainable dwarf annotations

2015-06-02 07:57:48 +02:00

atomic64_cx8_32.S

x86/debug: Remove perpetually broken, unmaintainable dwarf annotations

2015-06-02 07:57:48 +02:00

cache-smp.c

x86, lib: Add wbinvd smp helpers

2010-01-22 16:05:42 -08:00

checksum_32.S

x86/debug: Remove perpetually broken, unmaintainable dwarf annotations

2015-06-02 07:57:48 +02:00

clear_page_64.S

x86/debug: Remove perpetually broken, unmaintainable dwarf annotations

2015-06-02 07:57:48 +02:00

cmdline.c

x86, boot: Carve out early cmdline parsing function

2014-05-20 20:21:24 -07:00

cmpxchg8b_emu.S

x86/debug: Remove perpetually broken, unmaintainable dwarf annotations

2015-06-02 07:57:48 +02:00

cmpxchg16b_emu.S

x86/debug: Remove perpetually broken, unmaintainable dwarf annotations

2015-06-02 07:57:48 +02:00

copy_page_64.S

x86/debug: Remove perpetually broken, unmaintainable dwarf annotations

2015-06-02 07:57:48 +02:00

copy_user_64.S

x86/debug: Remove perpetually broken, unmaintainable dwarf annotations

2015-06-02 07:57:48 +02:00

csum-copy_64.S

x86/debug: Remove perpetually broken, unmaintainable dwarf annotations

2015-06-02 07:57:48 +02:00

csum-partial_64.c

x86: Fix common misspellings

2011-03-18 10:39:30 +01:00

csum-wrappers_64.c

x86-64: make csum_partial_copy_from_user() error handling consistent

2014-11-16 11:00:42 -08:00

delay.c

x86/asm/delay: Introduce an MWAITX-based delay with a configurable timer

2015-08-22 14:52:16 +02:00

getuser.S

x86/debug: Remove perpetually broken, unmaintainable dwarf annotations

2015-06-02 07:57:48 +02:00

inat.c

x86: Fix to decode grouped AVX with VEX pp bits

2012-02-11 15:11:35 +01:00

insn.c

x86/asm/decoder: Fix and enforce max instruction size in the insn decoder

2015-02-19 00:01:24 +01:00

iomap_copy_64.S

x86/debug: Remove perpetually broken, unmaintainable dwarf annotations

2015-06-02 07:57:48 +02:00

Makefile

x86/asm/entry: Move the 'thunk' functions to arch/x86/entry/

2015-06-04 07:37:33 +02:00

memcpy_32.c

asmlinkage, x86: Fix 32bit memcpy for LTO

2014-02-13 18:14:46 -08:00

memcpy_64.S

x86/debug: Remove perpetually broken, unmaintainable dwarf annotations

2015-06-02 07:57:48 +02:00

memmove_64.S

x86/debug: Remove perpetually broken, unmaintainable dwarf annotations

2015-06-02 07:57:48 +02:00

memset_64.S

x86/debug: Remove perpetually broken, unmaintainable dwarf annotations

2015-06-02 07:57:48 +02:00

misc.c

x86/boot: Further compress CPUs bootup message

2013-10-01 10:52:30 +02:00

mmx_32.c

x86/fpu: Rename i387.h to fpu/api.h

2015-05-19 15:47:30 +02:00

msr-reg-export.c

x86, pvops: Remove hooks for {rd,wr}msr_safe_regs

2012-06-07 11:41:08 -07:00

msr-reg.S

x86/debug: Remove perpetually broken, unmaintainable dwarf annotations

2015-06-02 07:57:48 +02:00

msr-smp.c

x86 / msr: add 64bit _on_cpu access functions

2013-10-17 00:36:06 +02:00

msr.c

x86: Fix typo preventing msr_set/clear_bit from having an effect

2014-05-09 08:42:32 -07:00

putuser.S

x86/debug: Remove perpetually broken, unmaintainable dwarf annotations

2015-06-02 07:57:48 +02:00

rwsem.S

x86/debug: Remove perpetually broken, unmaintainable dwarf annotations

2015-06-02 07:57:48 +02:00

string_32.c

x86/i386: Use less assembly in strlen(), speed things up a bit

2011-12-12 18:33:42 +01:00

strstr_32.c

x86: coding style fixes to arch/x86/lib/strstr_32.c

2008-08-15 16:53:24 +02:00

usercopy_32.c

mm/uaccess, mm/fault: Clarify that uaccess may only sleep if pagefaults are enabled

2015-05-19 08:39:14 +02:00

usercopy_64.c

x86: fix special __probe_kernel_write() tail zeroing case

2015-04-24 06:58:27 -07:00

usercopy.c

perf/x86: Fix copy_from_user_nmi() return if range is not ok

2015-07-06 14:09:27 +02:00

x86-opcode-map.txt

x86/asm/decoder: Explain CALLW discrepancy between Intel and AMD

2015-02-18 21:01:59 +01:00