Re: [PATCH 01/70] cpufreq: interactive: New 'interactive' governor

From	"Rafael J. Wysocki" <rjw@rjwysocki.net>
Newsgroups	linux.kernel
Subject	Re: [PATCH 01/70] cpufreq: interactive: New 'interactive' governor
Date	2015-10-28 01:40 +0100
Message-ID	<qomWu-3K3-11@gated-at.bofh.it> (permalink)
References	<qogo1-84h-5@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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Hi,

On Tuesday, October 27, 2015 06:29:49 PM Bálint Czobor wrote:
> From: Mike Chan <mike@android.com>
> 
> This governor is designed for latency-sensitive workloads, such as
> interactive user interfaces.  The interactive governor aims to be
> significantly more responsive to ramp CPU quickly up when CPU-intensive
> activity begins.
> 
> Existing governors sample CPU load at a particular rate, typically
> every X ms.  This can lead to under-powering UI threads for the period of
> time during which the user begins interacting with a previously-idle system
> until the next sample period happens.
> 
> The 'interactive' governor uses a different approach. Instead of sampling
> the CPU at a specified rate, the governor will check whether to scale the
> CPU frequency up soon after coming out of idle.  When the CPU comes out of
> idle, a timer is configured to fire within 1-2 ticks.  If the CPU is very
> busy from exiting idle to when the timer fires then we assume the CPU is
> underpowered and ramp to MAX speed.
> 
> If the CPU was not sufficiently busy to immediately ramp to MAX speed, then
> the governor evaluates the CPU load since the last speed adjustment,
> choosing the highest value between that longer-term load or the short-term
> load since idle exit to determine the CPU speed to ramp to.
> 
> A realtime thread is used for scaling up, giving the remaining tasks the
> CPU performance benefit, unlike existing governors which are more likely to
> schedule rampup work to occur after your performance starved tasks have
> completed.
> 
> The tuneables for this governor are:
> /sys/devices/system/cpu/cpufreq/interactive/min_sample_time:
> 	The minimum amount of time to spend at the current frequency before
> 	ramping down. This is to ensure that the governor has seen enough
> 	historic CPU load data to determine the appropriate workload.
> 	Default is 80000 uS.
> /sys/devices/system/cpu/cpufreq/interactive/go_maxspeed_load
> 	The CPU load at which to ramp to max speed.  Default is 85.
> 
> Change-Id: Ib2b362607c62f7c56d35f44a9ef3280f98c17585
> Signed-off-by: Mike Chan <mike@android.com>
> Signed-off-by: Todd Poynor <toddpoynor@google.com>
> Bug: 3152864
> Signed-off-by: Bálint Czobor <czoborbalint@gmail.com>

It's good to see that submitted, but it'll have to go through a detailed
review which is going to take some time.

One my observation after a cursory look at it is that at least some later
patches of the series modify drivers/cpufreq/cpufreq_interactive.c which is
a new file added by the first patch.  Is there any particular reason to
avoid folding all of those patches into the first one?

Thanks,
Rafael

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Thread

[PATCH 01/70] cpufreq: interactive: New 'interactive' governor Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:40 +0100
  [PATCH 57/70] cpufreq: interactive: fix compiling warnings Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:40 +0100
  [PATCH 56/70] cpufreq: interactive: delete timers for GOV_START Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:40 +0100
  [PATCH 41/70] cpufreq: interactive: fix race on governor start/stop Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:40 +0100
  [PATCH 32/70] cpufreq: interactive: specify duration of CPU speed boost pulse Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:40 +0100
  [PATCH 43/70] cpufreq: interactive: add io_is_busy interface Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:40 +0100
  [PATCH 39/70] cpufreq: interactive: don't handle transition notification if not enabled Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:40 +0100
  [PATCH 51/70] cpufreq: interactive: resched timer if max freq raised Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:40 +0100
  [PATCH 09/70] cpufreq: interactive: Separate speed target revalidate time and initial set time Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:40 +0100
  [PATCH 60/70] cpufreq: interactive: hold reference on global cpufreq kobject if needed Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:40 +0100
  [PATCH 24/70] cpufreq: interactive: use deferrable timer by default Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:40 +0100
  [PATCH 61/70] cpufreq: interactive: restructure CPUFREQ_GOV_LIMITS Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:40 +0100
  [PATCH 27/70] cpufreq: interactive: change speed according to current speed and target load Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:40 +0100
  [PATCH 07/70] cpufreq: interactive: adjust code and documentation to match Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:40 +0100
  [PATCH 29/70] cpufreq: interactive: allow arbitrary speed / target load mappings Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:40 +0100
  [PATCH 48/70] cpufreq: interactive: reduce chance of zero time delta on load eval Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:40 +0100
  [PATCH 64/70] cpufreq: interactive: prevents the frequency to directly raise above the hispeed_freq from a lower frequency. Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:40 +0100
  [PATCH 65/70] cpufreq: interactive: make common_tunables static Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:40 +0100
  [PATCH 69/70] cpufreq: interactive: Don't set floor_validate_time during boost Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:40 +0100
  [PATCH 37/70] cpufreq: interactive: default go_hispeed_load 99%, doc updates Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:40 +0100
  [PATCH 58/70] cpufreq: interactive: fix NULL pointer dereference at sysfs ops Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:40 +0100
  [PATCH 66/70] cpufreq: interactive: Fix compile errors in accordance with changes from 3.14 to 3.18 Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:40 +0100
  [PATCH 17/70] cpufreq: interactive: take idle notifications only when active Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:40 +0100
  [PATCH 35/70] cpufreq: interactive: fix racy timer stopping Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:40 +0100
  [PATCH 67/70] cpufreq: interactive: Put global cpufreq kobject on failure Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:40 +0100
  [PATCH 70/70] cpufreq: interactive: Round up timer_rate to match jiffy Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:40 +0100
  [PATCH 20/70] cpufreq: interactive: remove input_boost handling Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:40 +0100
  [PATCH 12/70] cpufreq: interactive: Add sysfs boost interface for hints from userspace Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:40 +0100
  [PATCH 22/70] cpufreq: interactive: run at fraction of hispeed_freq when load is low Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:40 +0100
  [PATCH 68/70] subsystem: CPU FREQUENCY DRIVERS- Set cpu_load calculation on current frequency Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:40 +0100
  [PATCH 13/70] cpufreq: interactive: set floor for boosted speed Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:40 +0100
  [PATCH 55/70] cpufreq: Interactive: Implement per policy instances of governor Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:40 +0100
  [PATCH 52/70] cpufreq: interactive: fix show_target_loads and show_above_hispeed_delay Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:40 +0100
  [PATCH 10/70] cpufreq: interactive: Boost frequency on touchscreen input Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:40 +0100
  [PATCH 62/70] cpufreq: interactive: turn boost_pulse off on boost off Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:50 +0100
  [PATCH 59/70] cpufreq: interactive: Use generic get_cpu_idle_time() from cpufreq.c Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:50 +0100
  [PATCH 54/70] cpufreq: interactive: Move definition of cpufreq_gov_interactive downwards Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:50 +0100
  [PATCH 53/70] cpufreq: interactive: Remove unnecessary cpu_online() check Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:50 +0100
  [PATCH 25/70] cpufreq: interactive: kick timer on idle exit past expiry Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:50 +0100
  [PATCH 47/70] cpufreq: interactive: handle errors from cpufreq_frequency_table_target Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:50 +0100
  [PATCH 63/70] cpufreq: interactive: remove compilation error from commit 49cc72365fb7ee87762a7ccc6a32ef68627216c5 Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:50 +0100
  [PATCH 44/70] cpufreq: interactive: fix crash on error paths in get_tokenized_data Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:50 +0100
  [PATCH 50/70] cpufreq: interactive: fix race on cpufreq TRANSITION notifier Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:50 +0100
  [PATCH 49/70] cpufreq: interactive: avoid underflow on active time calculation Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:50 +0100
  [PATCH 45/70] cpufreq: interactive: base above_hispeed_delay on target freq, not current Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:50 +0100
  [PATCH 46/70] cpufreq: interactive: fix uninitialized spinlock Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 18:50 +0100
  [PATCH 34/70] cpufreq: interactive: fix boosting logic Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 19:00 +0100
  [PATCH 38/70] cpufreq: interactive: init default values at compile time Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 19:00 +0100
  [PATCH 16/70] cpufreq: interactive: restart above_hispeed_delay at each hispeed load Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 19:00 +0100
  [PATCH 28/70] cpufreq: interactive: apply above_hispeed_delay to each step above hispeed Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 19:00 +0100
  [PATCH 23/70] cpufreq: interactive: pin timers to associated CPU Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 19:00 +0100
  [PATCH 18/70] cpufreq: interactive: keep freezer happy when not current governor Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 19:00 +0100
  [PATCH 21/70] cpufreq: interactive: always limit initial speed bump to hispeed Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 19:00 +0100
  [PATCH 36/70] cpufreq: interactive: fix race on timer restart on governor start Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 19:00 +0100
  [PATCH 19/70] cpufreq: interactive: handle speed up and down in the realtime task Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 19:00 +0100
  [PATCH 42/70] cpufreq: interactive: allow arbitrary speed / delay mappings Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 19:00 +0100
  [PATCH 26/70] cpufreq: interactive: trace actual speed in target speed decisions Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 19:00 +0100
  [PATCH 30/70] cpufreq: interactive: remove load since last speed change Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 19:00 +0100
  [PATCH 40/70] cpufreq: interactive: fix deadlock on spinlock in timer Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 19:00 +0100
  [PATCH 33/70] cpufreq: interactive: add timer slack to limit idle at speed > min Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 19:00 +0100
  [PATCH 31/70] cpufreq: interactive: adjust load for changes in speed Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 19:00 +0100
  [PATCH 04/70] cpufreq: interactive: set at least hispeed when above hispeed load Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 19:10 +0100
  [PATCH 02/70] cpufreq interactive governor: event tracing Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 19:10 +0100
  [PATCH 11/70] cpufreq: interactive: remove unused target_validate_time_in_idle Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 19:10 +0100
  [PATCH 05/70] cpufreq: interactive: don't drop speed if recently at higher load Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 19:10 +0100
  [PATCH 06/70] cpufreq: interactive: configurable delay before raising above hispeed Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 19:10 +0100
  [PATCH 08/70] cpufreq: interactive: base hispeed bump on target freq, not actual Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 19:10 +0100
  [PATCH 15/70] cpufreq-interactive: Compile fixup Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 19:10 +0100
  [PATCH 14/70] cpufreq: interactive: add boost pulse interface Bálint Czobor <czoborbalint@gmail.com> - 2015-10-27 19:10 +0100
  Re: [PATCH 01/70] cpufreq: interactive: New 'interactive' governor "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2015-10-28 01:40 +0100
    Re: [PATCH 01/70] cpufreq: interactive: New 'interactive' governor Viresh Kumar <viresh.kumar@linaro.org> - 2015-10-28 04:10 +0100
      Re: [PATCH 01/70] cpufreq: interactive: New 'interactive' governor Viresh Kumar <viresh.kumar@linaro.org> - 2015-10-29 02:50 +0100

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