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Marked deprecated for quite a while now...
Signed-off-by: Thomas Renninger <[email protected]>
Signed-off-by: Dave Jones <[email protected]>
CC: [email protected]
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calculate ondemand delay after dbs_check_cpu call because it can
modify rate_mult value
use freq_lo_jiffies value for the sub sample period of powersave_bias mode
Signed-off-by: Vincent Guittot <[email protected]>
Signed-off-by: Dave Jones <[email protected]>
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With cmwq, there's no reason for cpufreq drivers to use separate
workqueues. Remove the dedicated workqueues from cpufreq_conservative
and cpufreq_ondemand and use system_wq instead. The work items are
already sync canceled on stop, so it's already guaranteed that no work
is running on module exit.
Signed-off-by: Tejun Heo <[email protected]>
Acked-by: Dave Jones <[email protected]>
Cc: [email protected]
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Adds a new global tunable, sampling_down_factor. Set to 1 it makes no
changes from existing behavior, but set to greater than 1 (e.g. 100)
it acts as a multiplier for the scheduling interval for reevaluating
load when the CPU is at its top speed due to high load. This improves
performance by reducing the overhead of load evaluation and helping
the CPU stay at its top speed when truly busy, rather than shifting
back and forth in speed. This tunable has no effect on behavior at
lower speeds/lower CPU loads.
This patch is against 2.6.36-rc6.
This patch should help solve kernel bug 19672 "ondemand is slow".
Signed-off-by: David Niemi <[email protected]>
Acked-by: Venkatesh Pallipadi <[email protected]>
CC: Daniel Hollocher <[email protected]>
CC: <[email protected]>
CC: <[email protected]>
Signed-off-by: Dave Jones <[email protected]>
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For UP systems this is not required, and results in a more consistent
sample interval.
[[email protected]: coding-style fixes]
Signed-off-by: Jocelyn Falempe <[email protected]>
Signed-off-by: Mike Chan <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Dave Jones <[email protected]>
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Make simpler to read and call.
*** v3 - Always call when powersave_bias is enabled.
Acked-by: Venkatesh Pallipadi <[email protected]>
Signed-off-by: Mike Chan <[email protected]>
Signed-off-by: Dave Jones <[email protected]>
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'x86-cpu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
x86, hypervisor: add missing <linux/module.h>
Modify the VMware balloon driver for the new x86_hyper API
x86, hypervisor: Export the x86_hyper* symbols
x86: Clean up the hypervisor layer
x86, HyperV: fix up the license to mshyperv.c
x86: Detect running on a Microsoft HyperV system
x86, cpu: Make APERF/MPERF a normal table-driven flag
x86, k8: Fix build error when K8_NB is disabled
x86, cacheinfo: Disable index in all four subcaches
x86, cacheinfo: Make L3 cache info per node
x86, cacheinfo: Reorganize AMD L3 cache structure
x86, cacheinfo: Turn off L3 cache index disable feature in virtualized environments
x86, cacheinfo: Unify AMD L3 cache index disable checking
cpufreq: Unify sysfs attribute definition macros
powernow-k8: Fix frequency reporting
x86, cpufreq: Add APERF/MPERF support for AMD processors
x86: Unify APERF/MPERF support
powernow-k8: Add core performance boost support
x86, cpu: Add AMD core boosting feature flag to /proc/cpuinfo
Fix up trivial conflicts in arch/x86/kernel/cpu/intel_cacheinfo.c and
drivers/cpufreq/cpufreq_ondemand.c
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Pavel Machek pointed out that not all CPUs have an efficient
idle at high frequency. Specifically, older Intel and various
AMD cpus would get a higher powerusage when copying files from
USB.
Mike Chan pointed out that the same is true for various ARM
chips as well.
Thomas Renninger suggested to make this a sysfs tunable with a
reasonable default.
This patch adds a sysfs tunable for the new behavior, and uses
a very simple function to determine a reasonable default,
depending on the CPU vendor/type.
Signed-off-by: Arjan van de Ven <[email protected]>
Acked-by: Rik van Riel <[email protected]>
Acked-by: Pavel Machek <[email protected]>
Acked-by: Peter Zijlstra <[email protected]>
Cc: [email protected]
LKML-Reference: <[email protected]>
[ minor tidyup ]
Signed-off-by: Ingo Molnar <[email protected]>
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The ondemand cpufreq governor uses CPU busy time (e.g. not-idle
time) as a measure for scaling the CPU frequency up or down.
If the CPU is busy, the CPU frequency scales up, if it's idle,
the CPU frequency scales down. Effectively, it uses the CPU busy
time as proxy variable for the more nebulous "how critical is
performance right now" question.
This algorithm falls flat on its face in the light of workloads
where you're alternatingly disk and CPU bound, such as the ever
popular "git grep", but also things like startup of programs and
maildir using email clients... much to the chagarin of Andrew
Morton.
This patch changes the ondemand algorithm to count iowait time
as busy, not idle, time. As shown in the breakdown cases above,
iowait is performance critical often, and by counting iowait,
the proxy variable becomes a more accurate representation of the
"how critical is performance" question.
The problem and fix are both verified with the "perf timechar"
tool.
Signed-off-by: Arjan van de Ven <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Dave Jones <[email protected]>
Reviewed-by: Rik van Riel <[email protected]>
Acked-by: Peter Zijlstra <[email protected]>
LKML-Reference: <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
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Multiple modules used to define those which are with identical
functionality and were needlessly replicated among the different cpufreq
drivers. Push them into the header and remove duplication.
Signed-off-by: Borislav Petkov <[email protected]>
LKML-Reference: <[email protected]>
Reviewed-by: Thomas Renninger <[email protected]>
Signed-off-by: H. Peter Anvin <[email protected]>
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Dominik said:
target_freq cannot be below policy->min or above policy->max.
If it were, the whole cpufreq subsystem is broken.
But (answer):
I think the "ondemand" governor can ask for a target frequency that is
below policy->min.
...
A patch such as below may be needed to sanitize the target frequency
requested by "ondemand". The "conservative" governor already has this check:
Signed-off-by: Thomas Renninger <[email protected]>
Signed-off-by: Dave Jones <[email protected]>
# diff -bur x/drivers/cpufreq/cpufreq_ondemand.c.orig y/drivers/cpufreq/cpufreq_ondemand.c
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ondemand and conservative governors are messing up time units in the
code path where NO_HZ is not enabled and ignore_nice is set. The walltime
idletime stored is in jiffies and nice time calculation is happening in
microseconds.
The problem was reported and diagnosed by Alexander here.
http://marc.info/?l=linux-kernel&m=125752550404513&w=2
The patch below fixes this thinko.
Reported-by: Alexander Miller <[email protected]>
Tested-by: Alexander Miller <[email protected]>
Signed-off-by: Venkatesh Pallipadi <[email protected]>
Signed-off-by: Dave Jones <[email protected]>
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git://git.kernel.org/pub/scm/linux/kernel/git/davej/cpufreq
* 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/davej/cpufreq:
[CPUFREQ] Fix NULL ptr regression in powernow-k8
[CPUFREQ] Create a blacklist for processors that should not load the acpi-cpufreq module.
[CPUFREQ] Powernow-k8: Enable more than 2 low P-states
[CPUFREQ] remove rwsem lock from CPUFREQ_GOV_STOP call (second call site)
[CPUFREQ] ondemand - Use global sysfs dir for tuning settings
[CPUFREQ] Introduce global, not per core: /sys/devices/system/cpu/cpufreq
[CPUFREQ] Bail out of cpufreq_add_dev if the link for a managed CPU got created
[CPUFREQ] Factor out policy setting from cpufreq_add_dev
[CPUFREQ] Factor out interface creation from cpufreq_add_dev
[CPUFREQ] Factor out symlink creation from cpufreq_add_dev
[CPUFREQ] cleanup up -ENOMEM handling in cpufreq_add_dev
[CPUFREQ] Reduce scope of cpu_sys_dev in cpufreq_add_dev
[CPUFREQ] update Doc for cpuinfo_cur_freq and scaling_cur_freq
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Ondemand has only global variables for userspace tunings via sysfs.
But they were exposed per CPU which wrongly implies to the user that
his settings are applied per cpu. Also locking sysfs against concurrent
access won't be necessary anymore after deprecation time.
This means the ondemand config dir is moved:
/sys/devices/system/cpu/cpu*/cpufreq/ondemand ->
/sys/devices/system/cpu/cpufreq/ondemand
The old files will still exist, but reading or writing to them will
result in one (printk_once) deprecation msg to syslog per file.
Signed-off-by: Thomas Renninger <[email protected]>
Signed-off-by: Dave Jones <[email protected]>
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Conflicts:
arch/sparc/kernel/smp_64.c
arch/x86/kernel/cpu/perf_counter.c
arch/x86/kernel/setup_percpu.c
drivers/cpufreq/cpufreq_ondemand.c
mm/percpu.c
Conflicts in core and arch percpu codes are mostly from commit
ed78e1e078dd44249f88b1dd8c76dafb39567161 which substituted many
num_possible_cpus() with nr_cpu_ids. As for-next branch has moved all
the first chunk allocators into mm/percpu.c, the changes are moved
from arch code to mm/percpu.c.
Signed-off-by: Tejun Heo <[email protected]>
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Redesign the locking inside ondemand driver. Make dbs_mutex handle all the
global state changes inside the driver and invent a new percpu mutex
to serialize percpu timer and frequency limit change.
Signed-off-by: Venkatesh Pallipadi <[email protected]>
Signed-off-by: Dave Jones <[email protected]>
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Commit b14893a62c73af0eca414cfed505b8c09efc613c although it was very
much needed to properly cleanup ondemand timer, opened-up a can of worms
related to locking dependencies in cpufreq.
Patch here defines the need for dbs_mutex and cleans up its usage in
ondemand governor. This also resolves the lockdep warnings reported here
http://lkml.indiana.edu/hypermail/linux/kernel/0906.1/01925.html
http://lkml.indiana.edu/hypermail/linux/kernel/0907.0/00820.html
and few others..
Signed-off-by: Venkatesh Pallipadi <[email protected]>
Signed-off-by: Dave Jones <[email protected]>
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Percpu variable definition is about to be updated such that all percpu
symbols including the static ones must be unique. Update percpu
variable definitions accordingly.
* as,cfq: rename ioc_count uniquely
* cpufreq: rename cpu_dbs_info uniquely
* xen: move nesting_count out of xen_evtchn_do_upcall() and rename it
* mm: move ratelimits out of balance_dirty_pages_ratelimited_nr() and
rename it
* ipv4,6: rename cookie_scratch uniquely
* x86 perf_counter: rename prev_left to pmc_prev_left, irq_entry to
pmc_irq_entry and nmi_entry to pmc_nmi_entry
* perf_counter: rename disable_count to perf_disable_count
* ftrace: rename test_event_disable to ftrace_test_event_disable
* kmemleak: rename test_pointer to kmemleak_test_pointer
* mce: rename next_interval to mce_next_interval
[ Impact: percpu usage cleanups, no duplicate static percpu var names ]
Signed-off-by: Tejun Heo <[email protected]>
Reviewed-by: Christoph Lameter <[email protected]>
Cc: Ivan Kokshaysky <[email protected]>
Cc: Jens Axboe <[email protected]>
Cc: Dave Jones <[email protected]>
Cc: Jeremy Fitzhardinge <[email protected]>
Cc: linux-mm <[email protected]>
Cc: David S. Miller <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Steven Rostedt <[email protected]>
Cc: Li Zefan <[email protected]>
Cc: Catalin Marinas <[email protected]>
Cc: Andi Kleen <[email protected]>
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Update the documentation accordingly.
Cleanup and use printk_once.
Signed-off-by: Thomas Renninger <[email protected]>
Signed-off-by: Dave Jones <[email protected]>
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With this patch you have following minimal sampling rate restrictions:
Kernel restrictions:
If CONFIG_NO_HZ is set, the limit is 10ms fixed.
If CONFIG_NO_HZ is not set or no_hz=off boot parameter is used, the
limits depend on the CONFIG_HZ option:
HZ=1000: min=20000us (20ms)
HZ=250: min=80000us (80ms)
HZ=100: min=200000us (200ms)
HW restrictions:
Do not sample/poll more often than HW latency * 100 exported by the low
level cpufreq HW driver
The higher value of above restrictions is the minimal sampling rate
that can be set (and can be seen via ondemand/sampling_rate_min sysfs file)
Default sampling rate still is HW latency * 1000, but this will now end
up in lower values on latest (Intel and AMD) hardware as these can switch
really fast and sampling rate mostly was limited to the 80ms or 200ms
(depending on whether HZ=250 or HZ=1000 is used).
Signed-off-by: Thomas Renninger <[email protected]>
Cc: Pallipadi Venkatesh <[email protected]>
Signed-off-by: Dave Jones <[email protected]>
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* Rafael J. Wysocki ([email protected]) wrote:
> This message has been generated automatically as a part of a report
> of regressions introduced between 2.6.28 and 2.6.29.
>
> The following bug entry is on the current list of known regressions
> introduced between 2.6.28 and 2.6.29. Please verify if it still should
> be listed and let me know (either way).
>
>
> Bug-Entry : http://bugzilla.kernel.org/show_bug.cgi?id=13186
> Subject : cpufreq timer teardown problem
> Submitter : Mathieu Desnoyers <[email protected]>
> Date : 2009-04-23 14:00 (24 days old)
> References : http://marc.info/?l=linux-kernel&m=124049523515036&w=4
> Handled-By : Mathieu Desnoyers <[email protected]>
> Patch : http://patchwork.kernel.org/patch/19754/
> http://patchwork.kernel.org/patch/19753/
>
(updated changelog)
cpufreq fix timer teardown in ondemand governor
The problem is that dbs_timer_exit() uses cancel_delayed_work() when it should
use cancel_delayed_work_sync(). cancel_delayed_work() does not wait for the
workqueue handler to exit.
The ondemand governor does not seem to be affected because the
"if (!dbs_info->enable)" check at the beginning of the workqueue handler returns
immediately without rescheduling the work. The conservative governor in
2.6.30-rc has the same check as the ondemand governor, which makes things
usually run smoothly. However, if the governor is quickly stopped and then
started, this could lead to the following race :
dbs_enable could be reenabled and multiple do_dbs_timer handlers would run.
This is why a synchronized teardown is required.
The following patch applies to, at least, 2.6.28.x, 2.6.29.1, 2.6.30-rc2.
Depends on patch
cpufreq: remove rwsem lock from CPUFREQ_GOV_STOP call
Signed-off-by: Mathieu Desnoyers <[email protected]>
CC: Andrew Morton <[email protected]>
CC: [email protected]
CC: [email protected]
CC: [email protected]
CC: Ingo Molnar <[email protected]>
CC: [email protected]
CC: Ben Slusky <[email protected]>
Signed-off-by: Dave Jones <[email protected]>
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Limit sampling rate to transition_latency * 100 or kernel limits.
If sampling_rate is tried to be set too low, set the lowest allowed value.
Signed-off-by: Thomas Renninger <[email protected]>
Signed-off-by: Dave Jones <[email protected]>
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The same info can be obtained via the transition_latency sysfs file
Signed-off-by: Thomas Renninger <[email protected]>
Signed-off-by: Dave Jones <[email protected]>
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Signed-off-by: Dave Jones <[email protected]>
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ondemand micro-accounting of idle time changes broke ignore_nice_load
sysfs setting due to a thinko in the code.
The bug entry:
http://bugzilla.kernel.org/show_bug.cgi?id=12310
Reported-by: Jim Bray <[email protected]>
Signed-off-by: Venkatesh Pallipadi <[email protected]>
Signed-off-by: Dave Jones <[email protected]>
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Impact: use new cpumask API to reduce memory usage
This is part of an effort to reduce structure sizes for machines
configured with large NR_CPUS. cpumask_t gets replaced by
cpumask_var_t, which is either struct cpumask[1] (small NR_CPUS) or
struct cpumask * (large NR_CPUS).
Signed-off-by: Rusty Russell <[email protected]>
Signed-off-by: Mike Travis <[email protected]>
Acked-by: Dave Jones <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
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Use get_cpu()/put_cpu() in cpufreq_ondemand init routine, instead of
smp_processor_id() to avoid the following BUG:
[ 35.313118] BUG: using smp_processor_id() in preemptible [00000000] code=: modprobe/4952
[ 35.313132] caller is cpufreq_gov_dbs_init+0xa/0x8f [cpufreq_ondemand]
[ 35.313140] Pid: 4952, comm: modprobe Not tainted 2.6.27-rc5-mm1 #23
[ 35.313145] Call Trace:
[ 35.313158] [<ffffffff80361ff7>] debug_smp_processor_id+0xd7/0xe0
[ 35.313167] [<ffffffffa010800a>] cpufreq_gov_dbs_init+0xa/0x8f [cpufreq_ondemand]
[ 35.313176] [<ffffffff8020903b>] _stext+0x3b/0x160
[ 35.313185] [<ffffffff804768c5>] __mutex_unlock_slowpath+0xe5/0x190
[ 35.313195] [<ffffffff8026236a>] trace_hardirqs_on_caller+0xca/0x140
[ 35.313205] [<ffffffff8026ef4c>] sys_init_module+0xdc/0x210
[ 35.313212] [<ffffffff8020b7cb>] system_call_fastpath+0x16/0x1b
Signed-off-by: Andrea Righi <[email protected]>
Signed-off-by: Dave Jones <[email protected]>
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We don't need to export the governors for use as the default governor,
because the default governor will be built-in anyway and we can access
the symbol directly.
This also fixes the following sparse warnings:
drivers/cpufreq/cpufreq_conservative.c:578:25: warning: symbol 'cpufreq_gov_conservative' was not declared. Should it be static?
drivers/cpufreq/cpufreq_ondemand.c:582:25: warning: symbol 'cpufreq_gov_ondemand' was not declared. Should it be static?
drivers/cpufreq/cpufreq_performance.c:39:25: warning: symbol 'cpufreq_gov_performance' was not declared. Should it be static?
drivers/cpufreq/cpufreq_powersave.c:38:25: warning: symbol 'cpufreq_gov_powersave' was not declared. Should it be static?
drivers/cpufreq/cpufreq_userspace.c:190:25: warning: symbol 'cpufreq_gov_userspace' was not declared. Should it be static?
Signed-off-by: Sven Wegener <[email protected]>
Signed-off-by: Dave Jones <[email protected]>
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Use get_cpu_idle_time_us() to get micro-accounted idle information.
This enables ondemand to get more accurate idle and busy timings
than the jiffy based calculation. As a result, we can decrease
the ondemand safety gaurd band from 80-10 to 95-3.
Results in more aggressive power savings.
Signed-off-by: Venkatesh Pallipadi <[email protected]>
Signed-off-by: Dave Jones <[email protected]>
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Use a parameter for down differential, instead of hardcoded 10%. Follow-on
patch changes the down-differential dynamically, based on whether
we are using idle micro-accounting or not.
Signed-off-by: Venkatesh Pallipadi <[email protected]>
Signed-off-by: Dave Jones <[email protected]>
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idle-microaccounting
Preparatory changes for doing idle micro-accounting in ondemand governor.
get_cpu_idle_time() gets extra parameter and returns idle time and also the
wall time that corresponds to the idle time measurement.
Signed-off-by: Venkatesh Pallipadi <[email protected]>
Signed-off-by: Dave Jones <[email protected]>
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coordination
Change the load calculation algorithm in ondemand to work well with software
coordination of frequency across the dependent cpus.
Multiply individual CPU utilization with the average freq of that logical CPU
during the measurement interval (using getavg call). And find the max CPU
utilization number in terms of CPU freq. That number is then used to
get to the target freq for next sampling interval.
Signed-off-by: Venkatesh Pallipadi <[email protected]>
Signed-off-by: Dave Jones <[email protected]>
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Add a cpu parameter to __cpufreq_driver_getavg(). This is needed for software
cpufreq coordination where policy->cpu may not be same as the CPU on which we
want to getavg frequency.
A follow-on patch will use this parameter to getavg freq from all cpus
in policy->cpus.
Change since last patch. Fix the offline/online and suspend/resume
oops reported by Youquan Song <[email protected]>
Signed-off-by: Venkatesh Pallipadi <[email protected]>
Signed-off-by: Dave Jones <[email protected]>
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Add error handling for cpufreq_register_governor() error
Signed-off-by: Akinobu Mita <[email protected]>
Cc: [email protected]
Signed-off-by: Dave Jones <[email protected]>
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Change references from for_each_cpu_mask to for_each_cpu_mask_nr
where appropriate
Reviewed-by: Paul Jackson <[email protected]>
Reviewed-by: Christoph Lameter <[email protected]>
Signed-off-by: Mike Travis <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
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When the cpufreq driver starts up at boot time, it calls into the default
governor which might not be initialised yet. This hurts when the
governor's worker function relies on memory that is not yet set up by its
init function.
This migrates all governors from module_init() to fs_initcall() when being
the default, as was already done in cpufreq_performance when it was the
only possible choice. The performance governor is always initialized early
because it might be used as fallback even when not being the default.
Fixes at least one actual oops where ondemand is the default governor and
cpufreq_governor_dbs() uses the uninitialised kondemand_wq work-queue
during boot-time.
Signed-off-by: Johannes Weiner <[email protected]>
Cc: Dave Jones <[email protected]>
Cc: "Rafael J. Wysocki" <[email protected]>
Cc: Venkatesh Pallipadi <[email protected]>
Acked-by: Ingo Molnar <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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default
Depending on the transition latency of the HW for cpufreq switches, the
ondemand or conservative governor cannot be used with certain cpufreq
drivers. Still the ondemand should be the default governor on a wide range
of systems. This patch allows this and lets the governor fallback to the
performance governor at cpufreq driver load time, if the driver does not
support fast enough frequency switching.
Main benefit is that on e.g. installation or other systems without
userspace support a working dynamic cpufreq support can be achieved on most
systems by simply loading the cpufreq driver. This is especially essential
for recent x86(_64) laptop hardware which may rely on working dynamic
cpufreq OS support.
Signed-off-by: Thomas Renninger <[email protected]>
Signed-off-by: Venkatesh Pallipadi <[email protected]>
Cc: Russell King <[email protected]>
Cc: Bryan Wu <[email protected]>
Cc: Andi Kleen <[email protected]>
Cc: "Luck, Tony" <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: Benjamin Herrenschmidt <[email protected]>
Cc: Paul Mundt <[email protected]>
Cc: "David S. Miller" <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Dave Jones <[email protected]>
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With tickless kernel and software coordination os P-states, ondemand
can look at wrong idle statistics. This can happen when ondemand sampling
is happening on CPU 0 and due to software coordination sampling also looks at
utilization of CPU 1. If CPU 1 is in tickless state at that moment, its idle
statistics will not be uptodate and CPU 0 thinks CPU 1 is idle for less
amount of time than it actually is.
This can be resolved by looking at all the busy times of CPUs, which is
accurate, even with tickless, and use that to determine idle time in a
round about way (total time - busy time).
Thanks to Arjan for originally reporting the ondemand bug on
Lenovo T61.
Signed-off-by: Venkatesh Pallipadi <[email protected]>
Signed-off-by: Dave Jones <[email protected]>
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Due to rounding and inexact jiffy accounting, idle_ticks can sometimes
be higher than total_ticks. Make sure those cases are handled as
zero load case.
Signed-off-by: Venkatesh Pallipadi <[email protected]>
Signed-off-by: Dave Jones <[email protected]>
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Add a new deferrable delayed work init. This can be used to schedule work
that are 'unimportant' when CPU is idle and can be called later, when CPU
eventually comes out of idle.
Use this init in cpufreq ondemand governor.
Signed-off-by: Venkatesh Pallipadi <[email protected]>
Cc: Dave Jones <[email protected]>
Cc: Oleg Nesterov <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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Looks like dbs_timer() is very careful wrt per_cpu(cpu_dbs_info),
and it doesn't need the help of WORK_STRUCT_NOAUTOREL.
Signed-off-by: Oleg Nesterov <[email protected]>
Acked-By: David Howells <[email protected]>
Signed-off-by: Dave Jones <[email protected]>
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Signed-off-by: Dave Jones <[email protected]>
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Eliminate flush_workqueue in cpufreq_governor(STOP) callpath. Using flush
there has a deadlock potential as in
http://uwsg.iu.edu/hypermail/linux/kernel/0611.3/1223.html
Also, cleanup the locking issues with do_dbs_timer delayed_work callback. As
it changes the CPU frequency using __cpufreq_target, it needs to have
policy_rwsem in write mode, which also protects it from hot plug.
Signed-off-by: Venkatesh Pallipadi <[email protected]>
Cc: Gautham R Shenoy <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Dave Jones <[email protected]>
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Restructure the delayed_work callback in ondemand.
This eliminates the need for smp_processor_id in the callback function and
also helps in proper locking and avoiding flush_workqueue when stopping the
governor (done in subsequent patch).
Signed-off-by: Venkatesh Pallipadi <[email protected]>
Cc: Gautham R Shenoy <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Dave Jones <[email protected]>
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The hotplug CPU locking in cpufreq is horrendous. No-one seems to care
enough to fix it, so just remove it so that the 99.9% of the real world
users of this code can use cpufreq without being bothered by warnings.
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Dave Jones <[email protected]>
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Conflicts:
drivers/cpufreq/cpufreq.c
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Fix up for make allyesconfig.
Signed-Off-By: David Howells <[email protected]>
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Clean up cpufreq subsystem to fix coding style issues and to improve
the readability.
Signed-off-by: Gautham R Shenoy <[email protected]>
Signed-off-by: Dave Jones <[email protected]>
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Signed-off-by: Jeff Garzik <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Dave Jones <[email protected]>
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Enable ondemand governor and acpi-cpufreq to use IA32_APERF and IA32_MPERF MSR
to get active frequency feedback for the last sampling interval. This will
make ondemand take right frequency decisions when hardware coordination of
frequency is going on.
Without APERF/MPERF, ondemand can take wrong decision at times due
to underlying hardware coordination or TM2.
Example:
* CPU 0 and CPU 1 are hardware cooridnated.
* CPU 1 running at highest frequency.
* CPU 0 was running at highest freq. Now ondemand reduces it to
some intermediate frequency based on utilization.
* Due to underlying hardware coordination with other CPU 1, CPU 0 continues to
run at highest frequency (as long as other CPU is at highest).
* When ondemand samples CPU 0 again next time, without actual frequency
feedback from APERF/MPERF, it will think that previous frequency change
was successful and can go to wrong target frequency. This is because it
thinks that utilization it has got this sampling interval is when running at
intermediate frequency, rather than actual highest frequency.
More information about IA32_APERF IA32_MPERF MSR:
Refer to IA-32 Intel® Architecture Software Developer's Manual at
http://developer.intel.com
Signed-off-by: Venkatesh Pallipadi <[email protected]>
Signed-off-by: Dave Jones <[email protected]>
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