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| author | Chris Redpath <chris.redpath@arm.com> | 2012-11-16 10:03:00 +0000 |
|---|---|---|
| committer | Jon Medhurst <tixy@linaro.org> | 2013-07-17 11:12:27 +0100 |
| commit | 71b5dbd6d527d5de8aaef7e1f8658df95caf28aa (patch) | |
| tree | 58a0edceef4db340f35244e76e74d1206f2f315b /arch/arm | |
| parent | 0e48eed05c47aa2e00b772a519b36286e466621e (diff) | |
ARM: Experimental Frequency-Invariant Load Scaling Patch
Evaluation Patch to investigate using load as a representation of the
amount of POTENTIAL cpu compute capacity used rather than a representation
of the CURRENT cpu compute capacity.
If CPUFreq is enabled, scales load in accordance with frequency.
Powersave/performance CPUFreq governors are detected and scaling is
disabled while these governors are in use. This is because when a
single-frequency governor is in use, potential CPU capacity is static.
So long as the governors and CPUFreq subsystem correctly report the
frequencies available, the scaling should self tune.
Adds an additional file to sysfs to allow this feature to be disabled
for experimentation.
/sys/kernel/hmp/frequency_invariant_load_scale
write 0 to disable, 1 to enable.
Signed-off-by: Chris Redpath <chris.redpath@arm.com>
Diffstat (limited to 'arch/arm')
| -rw-r--r-- | arch/arm/Kconfig | 15 |
1 files changed, 15 insertions, 0 deletions
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig index f0a5a0787ea6..bc79c57d78c4 100644 --- a/arch/arm/Kconfig +++ b/arch/arm/Kconfig @@ -1564,6 +1564,21 @@ config HMP_VARIABLE_SCALE (1002/1024)^(LOAD_AVG_PERIOD/load_avg_period_ms) but it remove intermadiate overflows in computation. +config HMP_FREQUENCY_INVARIANT_SCALE + bool "(EXPERIMENTAL) Frequency-Invariant Tracked Load for HMP" + depends on HMP_VARIABLE_SCALE && CPU_FREQ + help + Scales the current load contribution in line with the frequency + of the CPU that the task was executed on. + In this version, we use a simple linear scale derived from the + maximum frequency reported by CPUFreq. + Restricting tracked load to be scaled by the CPU's frequency + represents the consumption of possible compute capacity + (rather than consumption of actual instantaneous capacity as + normal) and allows the HMP migration's simple threshold + migration strategy to interact more predictably with CPUFreq's + asynchronous compute capacity changes. + config HAVE_ARM_SCU bool help |