Eric Lee / smarc-fsl-linux-kernel

05 Oct, 2017

1 commit

  • bbaa715da   cpufreq: Add android's 'interactive' governor ... Browse Code »

    Interactive governor has lived in Android sources for a very long time
    and this commit is based on the code present in following branch:

    https://android.googlesource.com/kernel/common android-4.4

    The Interactive governor is designed for latency-sensitive workloads,
    such as interactive user interfaces like the mobile phones and tablets.
    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 and then update the frequency from a work-handler. 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.

    A real-time thread is used for scaling up, giving the remaining tasks
    the CPU performance benefit, unlike existing governors which are more
    likely to schedule ramp-up work to occur after your performance starved
    tasks have completed.

    The Android version of interactive governor also checks whether to scale
    the CPU frequency up soon after coming out of idle. When the CPU comes
    out of idle, the governor check if the CPU sampling is overdue or not.
    If yes, it immediately starts the sampling. Otherwise, the utilization
    hooks from the scheduler handle the sampling later. If the CPU is very
    busy from exiting idle to when the evaluation happens, then it assumes
    that the CPU is under-powered and ramps it 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.

    Idle notifiers will be be handled later and are not included for now.

    The core of this code is written and maintained (in Android
    repositories) by Mike Chan and Todd Poyner over a long period of time.

    Vireshk has made changes to to the governor to align it with the current
    practices followed with mainline governors, like using utilization hooks
    from the scheduler and handling kobject (for governor's sysfs directory)
    in a race free manner. And of course this included general cleanup of
    the governor as well.

    Signed-off-by: Mike Chan
    Signed-off-by: Todd Poynor
    Signed-off-by: Viresh Kumar

    ---
    V1->V2:
    - Changes to fix compilation issues with updated mainline
    - Timer APIs got updated
    - s/mod_timer_pinned/mod_timer
    - s/init_timer/init_timer_pinned
    - Updated prototypes of cpufreq_frequency_table_target() and
    update_util_handler()

    Viresh Kumar
     

05 Jun, 2015

1 commit

  • 1df1b3618   Documentation, intel_pstate: Improve legacy mode internal governors description ... Browse Code »

    The current documentation is incomplete wrt the intel_pstate legacy
    internal governors. The confusion comes from the general cpufreq
    governors which also use the names performance and powersave. This patch
    better differentiates between the two sets of governors and gives an
    explanation of how the internal P-state governors behave differently from
    one another.

    Also fix two minor typos.

    Cc: Prarit Bhargava
    Cc: "Rafael J. Wysocki"
    Cc: Kristen Carlson Accardi
    Cc: Dirk Brandewie
    Cc: x86@kernel.org
    Acked-by: Viresh Kumar
    Signed-off-by: Prarit Bhargava
    Signed-off-by: Jonathan Corbet

    Prarit Bhargava
     

26 Oct, 2013

1 commit

  • 9c0ebcf78   cpufreq: Implement light weight ->target_index() routine ... Browse Code »

    Currently, the prototype of cpufreq_drivers target routines is:

    int target(struct cpufreq_policy *policy, unsigned int target_freq,
    unsigned int relation);

    And most of the drivers call cpufreq_frequency_table_target() to get a valid
    index of their frequency table which is closest to the target_freq. And they
    don't use target_freq and relation after that.

    So, it makes sense to just do this work in cpufreq core before calling
    cpufreq_frequency_table_target() and simply pass index instead. But this can be
    done only with drivers which expose their frequency table with cpufreq core. For
    others we need to stick with the old prototype of target() until those drivers
    are converted to expose frequency tables.

    This patch implements the new light weight prototype for target_index() routine.
    It looks like this:

    int target_index(struct cpufreq_policy *policy, unsigned int index);

    CPUFreq core will call cpufreq_frequency_table_target() before calling this
    routine and pass index to it. Because CPUFreq core now requires to call routines
    present in freq_table.c CONFIG_CPU_FREQ_TABLE must be enabled all the time.

    This also marks target() interface as deprecated. So, that new drivers avoid
    using it. And Documentation is updated accordingly.

    It also converts existing .target() to newly defined light weight
    .target_index() routine for many driver.

    Acked-by: Hans-Christian Egtvedt
    Acked-by: Jesper Nilsson
    Acked-by: Linus Walleij
    Acked-by: Russell King
    Acked-by: David S. Miller
    Tested-by: Andrew Lunn
    Signed-off-by: Viresh Kumar
    Signed-off-by: Rafael J. Wysocki

    Viresh Kumar
     

06 May, 2013

1 commit

  • 534c97b09   Merge branch 'timers-nohz-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip ... Browse Code »

    Pull 'full dynticks' support from Ingo Molnar:
    "This tree from Frederic Weisbecker adds a new, (exciting! :-) core
    kernel feature to the timer and scheduler subsystems: 'full dynticks',
    or CONFIG_NO_HZ_FULL=y.

    This feature extends the nohz variable-size timer tick feature from
    idle to busy CPUs (running at most one task) as well, potentially
    reducing the number of timer interrupts significantly.

    This feature got motivated by real-time folks and the -rt tree, but
    the general utility and motivation of full-dynticks runs wider than
    that:

    - HPC workloads get faster: CPUs running a single task should be able
    to utilize a maximum amount of CPU power. A periodic timer tick at
    HZ=1000 can cause a constant overhead of up to 1.0%. This feature
    removes that overhead - and speeds up the system by 0.5%-1.0% on
    typical distro configs even on modern systems.

    - Real-time workload latency reduction: CPUs running critical tasks
    should experience as little jitter as possible. The last remaining
    source of kernel-related jitter was the periodic timer tick.

    - A single task executing on a CPU is a pretty common situation,
    especially with an increasing number of cores/CPUs, so this feature
    helps desktop and mobile workloads as well.

    The cost of the feature is mainly related to increased timer
    reprogramming overhead when a CPU switches its tick period, and thus
    slightly longer to-idle and from-idle latency.

    Configuration-wise a third mode of operation is added to the existing
    two NOHZ kconfig modes:

    - CONFIG_HZ_PERIODIC: [formerly !CONFIG_NO_HZ], now explicitly named
    as a config option. This is the traditional Linux periodic tick
    design: there's a HZ tick going on all the time, regardless of
    whether a CPU is idle or not.

    - CONFIG_NO_HZ_IDLE: [formerly CONFIG_NO_HZ=y], this turns off the
    periodic tick when a CPU enters idle mode.

    - CONFIG_NO_HZ_FULL: this new mode, in addition to turning off the
    tick when a CPU is idle, also slows the tick down to 1 Hz (one
    timer interrupt per second) when only a single task is running on a
    CPU.

    The .config behavior is compatible: existing !CONFIG_NO_HZ and
    CONFIG_NO_HZ=y settings get translated to the new values, without the
    user having to configure anything. CONFIG_NO_HZ_FULL is turned off by
    default.

    This feature is based on a lot of infrastructure work that has been
    steadily going upstream in the last 2-3 cycles: related RCU support
    and non-periodic cputime support in particular is upstream already.

    This tree adds the final pieces and activates the feature. The pull
    request is marked RFC because:

    - it's marked 64-bit only at the moment - the 32-bit support patch is
    small but did not get ready in time.

    - it has a number of fresh commits that came in after the merge
    window. The overwhelming majority of commits are from before the
    merge window, but still some aspects of the tree are fresh and so I
    marked it RFC.

    - it's a pretty wide-reaching feature with lots of effects - and
    while the components have been in testing for some time, the full
    combination is still not very widely used. That it's default-off
    should reduce its regression abilities and obviously there are no
    known regressions with CONFIG_NO_HZ_FULL=y enabled either.

    - the feature is not completely idempotent: there is no 100%
    equivalent replacement for a periodic scheduler/timer tick. In
    particular there's ongoing work to map out and reduce its effects
    on scheduler load-balancing and statistics. This should not impact
    correctness though, there are no known regressions related to this
    feature at this point.

    - it's a pretty ambitious feature that with time will likely be
    enabled by most Linux distros, and we'd like you to make input on
    its design/implementation, if you dislike some aspect we missed.
    Without flaming us to crisp! :-)

    Future plans:

    - there's ongoing work to reduce 1Hz to 0Hz, to essentially shut off
    the periodic tick altogether when there's a single busy task on a
    CPU. We'd first like 1 Hz to be exposed more widely before we go
    for the 0 Hz target though.

    - once we reach 0 Hz we can remove the periodic tick assumption from
    nr_running>=2 as well, by essentially interrupting busy tasks only
    as frequently as the sched_latency constraints require us to do -
    once every 4-40 msecs, depending on nr_running.

    I am personally leaning towards biting the bullet and doing this in
    v3.10, like the -rt tree this effort has been going on for too long -
    but the final word is up to you as usual.

    More technical details can be found in Documentation/timers/NO_HZ.txt"

    * 'timers-nohz-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (39 commits)
    sched: Keep at least 1 tick per second for active dynticks tasks
    rcu: Fix full dynticks' dependency on wide RCU nocb mode
    nohz: Protect smp_processor_id() in tick_nohz_task_switch()
    nohz_full: Add documentation.
    cputime_nsecs: use math64.h for nsec resolution conversion helpers
    nohz: Select VIRT_CPU_ACCOUNTING_GEN from full dynticks config
    nohz: Reduce overhead under high-freq idling patterns
    nohz: Remove full dynticks' superfluous dependency on RCU tree
    nohz: Fix unavailable tick_stop tracepoint in dynticks idle
    nohz: Add basic tracing
    nohz: Select wide RCU nocb for full dynticks
    nohz: Disable the tick when irq resume in full dynticks CPU
    nohz: Re-evaluate the tick for the new task after a context switch
    nohz: Prepare to stop the tick on irq exit
    nohz: Implement full dynticks kick
    nohz: Re-evaluate the tick from the scheduler IPI
    sched: New helper to prevent from stopping the tick in full dynticks
    sched: Kick full dynticks CPU that have more than one task enqueued.
    perf: New helper to prevent full dynticks CPUs from stopping tick
    perf: Kick full dynticks CPU if events rotation is needed
    ...

    Linus Torvalds
     

10 Apr, 2013

1 commit

  • 9c5320c8e   cpufreq: AMD "frequency sensitivity feedback" powersave bias for ondemand governor ... Browse Code »

    Future AMD processors, starting with Family 16h, can provide software
    with feedback on how the workload may respond to frequency change --
    memory-bound workloads will not benefit from higher frequency, where
    as compute-bound workloads will. This patch enables this "frequency
    sensitivity feedback" to aid the ondemand governor to make better
    frequency change decisions by hooking into the powersave bias.

    Signed-off-by: Jacob Shin
    Acked-by: Thomas Renninger
    Acked-by: Borislav Petkov
    Acked-by: Viresh Kumar
    Signed-off-by: Rafael J. Wysocki

    Jacob Shin
     

03 Apr, 2013

1 commit

  • 3451d0243   nohz: Rename CONFIG_NO_HZ to CONFIG_NO_HZ_COMMON ... Browse Code »

    We are planning to convert the dynticks Kconfig options layout
    into a choice menu. The user must be able to easily pick
    any of the following implementations: constant periodic tick,
    idle dynticks, full dynticks.

    As this implies a mutual exclusion, the two dynticks implementions
    need to converge on the selection of a common Kconfig option in order
    to ease the sharing of a common infrastructure.

    It would thus seem pretty natural to reuse CONFIG_NO_HZ to
    that end. It already implements all the idle dynticks code
    and the full dynticks depends on all that code for now.
    So ideally the choice menu would propose CONFIG_NO_HZ_IDLE and
    CONFIG_NO_HZ_EXTENDED then both would select CONFIG_NO_HZ.

    On the other hand we want to stay backward compatible: if
    CONFIG_NO_HZ is set in an older config file, we want to
    enable CONFIG_NO_HZ_IDLE by default.

    But we can't afford both at the same time or we run into
    a circular dependency:

    1) CONFIG_NO_HZ_IDLE and CONFIG_NO_HZ_EXTENDED both select
    CONFIG_NO_HZ
    2) If CONFIG_NO_HZ is set, we default to CONFIG_NO_HZ_IDLE

    We might be able to support that from Kconfig/Kbuild but it
    may not be wise to introduce such a confusing behaviour.

    So to solve this, create a new CONFIG_NO_HZ_COMMON option
    which gathers the common code between idle and full dynticks
    (that common code for now is simply the idle dynticks code)
    and select it from their referring Kconfig.

    Then we'll later create CONFIG_NO_HZ_IDLE and map CONFIG_NO_HZ
    to it for backward compatibility.

    Signed-off-by: Frederic Weisbecker
    Cc: Andrew Morton
    Cc: Chris Metcalf
    Cc: Christoph Lameter
    Cc: Geoff Levand
    Cc: Gilad Ben Yossef
    Cc: Hakan Akkan
    Cc: Ingo Molnar
    Cc: Kevin Hilman
    Cc: Li Zhong
    Cc: Namhyung Kim
    Cc: Paul E. McKenney
    Cc: Paul Gortmaker
    Cc: Peter Zijlstra
    Cc: Steven Rostedt
    Cc: Thomas Gleixner

    Frederic Weisbecker
     

01 Apr, 2013

1 commit

08 Nov, 2011

1 commit

  • e7cbb5b56   Doc: cpufreq: Fix typo and outdated line ... Browse Code »

    'sampling_rate_max' was removed with commit ef598549 ("[...] Remove
    deprecated sysfs file sampling_rate_max"), so its line can be dropped
    from governors.txt. And 'show_sampling_rate_min' is a typo: the sysfs
    file is called 'sampling_rate_min'.

    Signed-off-by: Paul Bolle
    Signed-off-by: Jiri Kosina

    Paul Bolle
     

09 Aug, 2011

1 commit

17 Mar, 2011

1 commit

13 Jan, 2010

1 commit

15 Jun, 2009

1 commit

25 Feb, 2009

2 commits

27 Jul, 2008

1 commit

21 May, 2008

1 commit

04 Oct, 2006

3 commits

01 Dec, 2005

1 commit

26 Jun, 2005

1 commit

  • 594dd2c98   [PATCH] cpufreq: governors documentation fixes ... Browse Code »

    I corrected a small error and enhanced the govenor.txt file with the
    ondemand daemon because the kernel configs link to the documentation but
    ondemand wasn't documentated. Feel free to include the patch in the
    attachment.

    Cc: Dominik Brodowski
    Cc: Dave Jones
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Nico Golde
     

17 Apr, 2005

1 commit

  • 1da177e4c   Linux-2.6.12-rc2 ... Browse Code »

    Initial git repository build. I'm not bothering with the full history,
    even though we have it. We can create a separate "historical" git
    archive of that later if we want to, and in the meantime it's about
    3.2GB when imported into git - space that would just make the early
    git days unnecessarily complicated, when we don't have a lot of good
    infrastructure for it.

    Let it rip!

    Linus Torvalds