Commit Graph

30 Commits

Author SHA1 Message Date
Dave Jones
3906f4edee [CPUFREQ] Fix sparse warning in ondemand
drivers/cpufreq/cpufreq_ondemand.c:323:2: warning: Using plain integer as NULL pointer

Signed-off-by: Dave Jones <davej@redhat.com>
2006-09-05 17:15:47 -04:00
Adrian Bunk
b5ecf60fe6 [CPUFREQ] make drivers/cpufreq/cpufreq_ondemand.c:powersave_bias_target() static
This patch makes the needlessly global powersave_bias_target() static.

Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Dave Jones <davej@redhat.com>
2006-08-14 01:18:54 -04:00
Alexey Starikovskiy
05ca0350e8 [CPUFREQ][2/2] ondemand: updated add powersave_bias tunable
ondemand selects the minimum frequency that can retire
a workload with negligible idle time -- ideally resulting in the highest
performance/power efficiency with negligible performance impact.

But on some systems and some workloads, this algorithm
is more performance biased than necessary, and
de-tuning it a bit to allow some performance impact
can save measurable power.

This patch adds a "powersave_bias" tunable to ondemand
to allow it to reduce its target frequency by a specified percent.

By default, the powersave_bias is 0 and has no effect.
powersave_bias is in units of 0.1%, so it has an effective range
of 1 through 1000, resulting in 0.1% to 100% impact.

In practice, users will not be able to detect a difference between
0.1% increments, but 1.0% increments turned out to be too large.
Also, the max value of 1000 (100%) would simply peg the system
in its deepest power saving P-state, unless the processor really has
a hardware P-state at 0Hz:-)

For example, If ondemand requests 2.0GHz based on utilization,
and powersave_bias=100, this code will knock 10% off the target
and seek  a target of 1.8GHz instead of 2.0GHz until the
next sampling.  If 1.8 is an exact match with an hardware frequency
we use it, otherwise we average our time between the frequency
next higher than 1.8 and next lower than 1.8.

Note that a user or administrative program can change powersave_bias
at run-time depending on how they expect the system to be used.

Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi at intel.com>
Signed-off-by: Alexey Starikovskiy <alexey.y.starikovskiy at intel.com>
Signed-off-by: Dave Jones <davej@redhat.com>
2006-08-11 17:59:57 -04:00
Alexey Starikovskiy
1ce28d6b19 [CPUFREQ][1/2] ondemand: updated tune for hardware coordination
Try to make dbs_check_cpu() call on all CPUs at the same jiffy.
This will help when multiple cores share P-states via Hardware Coordination.

Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi at intel.com>
Signed-off-by: Alexey Starikovskiy <alexey.y.starikovskiy at intel.com>
Signed-off-by: Dave Jones <davej@redhat.com>
2006-08-11 17:59:56 -04:00
Arjan van de Ven
153d7f3fca [PATCH] Reorganize the cpufreq cpu hotplug locking to not be totally bizare
The patch below moves the cpu hotplugging higher up in the cpufreq
layering; this is needed to avoid recursive taking of the cpu hotplug
lock and to otherwise detangle the mess.

The new rules are:
1. you must do lock_cpu_hotplug() around the following functions:
   __cpufreq_driver_target
   __cpufreq_governor (for CPUFREQ_GOV_LIMITS operation only)
   __cpufreq_set_policy
2. governer methods (.governer) must NOT take the lock_cpu_hotplug()
   lock in any way; they are called with the lock taken already
3. if your governer spawns a thread that does things, like calling
   __cpufreq_driver_target, your thread must honor rule #1.
4. the policy lock and other cpufreq internal locks nest within
   the lock_cpu_hotplug() lock.

I'm not entirely happy about how the __cpufreq_governor rule ended up
(conditional locking rule depending on the argument) but basically all
callers pass this as a constant so it's not too horrible.

The patch also removes the cpufreq_governor() function since during the
locking audit it turned out to be entirely unused (so no need to fix it)

The patch works on my testbox, but it could use more testing
(otoh... it can't be much worse than the current code)

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-07-26 07:21:40 -07:00
Linus Torvalds
2cd7cbdf4b [cpufreq] ondemand: make shutdown sequence more robust
Shutting down the ondemand policy was fraught with potential
problems, causing issues for SMP suspend (which wants to hot-
unplug) all but the last CPU.

This should fix at least the worst problems (divide-by-zero
and infinite wait for the workqueue to shut down).

Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-07-23 12:05:00 -07:00
Venkatesh Pallipadi
ffac80e925 [CPUFREQ] Misc cleanups in ondemand.
Misc cleanups in ondemand. Should have zero functional impact.
Also adding Alexey as author.

Signed-off-by: Alexey Starikovskiy <alexey.y.starikovskiy@intel.com>
Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Dave Jones <davej@redhat.com>
2006-06-30 01:36:40 -04:00
Venkatesh Pallipadi
2f8a835c70 [CPUFREQ] Make ondemand sampling per CPU and remove the mutex usage in sampling path.
Make ondemand sampling per CPU and remove the mutex usage in sampling path.

Signed-off-by: Alexey Starikovskiy <alexey.y.starikovskiy@intel.com>
Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Dave Jones <davej@redhat.com>
2006-06-30 01:33:31 -04:00
Venkatesh Pallipadi
ccb2fe209d [CPUFREQ] Remove slowdown from ondemand sampling path.
Remove slowdown from ondemand sampling path. This reduces the code path length
in dbs_check_cpu() by half. slowdown was not used by ondemand by default.
If there are any user level tools that were using this tunable, they
may report error now.

Signed-off-by: Alexey Starikovskiy <alexey.y.starikovskiy@intel.com>
Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Dave Jones <davej@redhat.com>
2006-06-30 01:29:47 -04:00
Andrew Morton
138a0128c0 [PATCH] cpufreq build fix
drivers/cpufreq/cpufreq_ondemand.c: In function 'do_dbs_timer':
drivers/cpufreq/cpufreq_ondemand.c:374: warning: implicit declaration of function 'lock_cpu_hotplug'
drivers/cpufreq/cpufreq_ondemand.c:381: warning: implicit declaration of function 'unlock_cpu_hotplug'
drivers/cpufreq/cpufreq_conservative.c: In function 'do_dbs_timer':
drivers/cpufreq/cpufreq_conservative.c:425: warning: implicit declaration of function 'lock_cpu_hotplug'
drivers/cpufreq/cpufreq_conservative.c:432: warning: implicit declaration of function 'unlock_cpu_hotplug'

Cc: Dave Jones <davej@codemonkey.org.uk>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-23 08:47:27 -07:00
Venkatesh Pallipadi
4ec223d02f [CPUFREQ] Fix ondemand vs suspend deadlock
Rootcaused the bug to a deadlock in cpufreq and ondemand. Due to non-existent
ordering between cpu_hotplug lock and dbs_mutex. Basically a race condition
between cpu_down() and do_dbs_timer().

cpu_down() flow:
* cpu_down() call for CPU 1
* Takes hot plug lock
* Calls pre down notifier
*     cpufreq notifier handler calls cpufreq_driver_target() which takes
      cpu_hotplug lock again. OK as cpu_hotplug lock is recursive in same
      process context
* CPU 1 goes down
* Calls post down notifier
*     cpufreq notifier handler calls ondemand event stop which takes dbs_mutex

So, cpu_hotplug lock is taken before dbs_mutex in this flow.

do_dbs_timer is triggerred by a periodic timer event.
It first takes dbs_mutex and then takes cpu_hotplug lock in
cpufreq_driver_target().
Note the reverse order here compared to above. So, if this timer event happens
at right moment during cpu_down, system will deadlok.

Attached patch fixes the issue for both ondemand and conservative.

Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Dave Jones <davej@redhat.com>
2006-06-21 18:30:26 -04:00
Andi Kleen
6810b548b2 [PATCH] x86_64: Move ondemand timer into own work queue
Taking the cpu hotplug semaphore in a normal events workqueue
is unsafe because other tasks can wait for any workqueues with
it hold. This results in a deadlock.

Move the DBS timer into its own work queue which is not
affected by other work queue flushes to avoid this.

Has been acked by Venkatesh.

Cc: venkatesh.pallipadi@intel.com
Cc: cpufreq@lists.linux.org.uk
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-05-08 09:34:56 -07:00
Dominik Brodowski
7c9d8c0e84 [PATCH] cpufreq_ondemand: add range check
Assert that cpufreq_target is, at least, called with the minimum frequency
allowed by this policy, not something lower. It triggered problems on ARM.

Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
2006-03-26 11:11:03 +02:00
Eric Piel
9cbad61b41 [PATCH] cpufreq_ondemand: keep ignore_nice_load value when it is reselected
Keep the value of ignore_nice_load of the ondemand governor even after
the governor has been deselected and selected back. This is the behavior
of the other exported values of the ondemand governor and it's much more
user-friendly.

Signed-off-by: Eric Piel <eric.piel@tremplin-utc.net>
Acked-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
2006-03-26 10:46:18 +02:00
Eric Piel
ff8c288d7d [PATCH] cpufreq_ondemand: Warn if it cannot run due to too long transition latency
Display a warning if the ondemand governor can not be selected due to a
transition latency of the cpufreq driver which is too long.

Signed-off-by: Eric Piel <eric.piel@tremplin-utc.net>
Acked-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
2006-03-26 10:43:06 +02:00
Dave Jones
32ee8c3e47 [CPUFREQ] Lots of whitespace & CodingStyle cleanup.
Signed-off-by: Dave Jones <davej@redhat.com>
2006-02-28 00:43:23 -05:00
akpm@osdl.org
3fc54d37ab [CPUFREQ] Convert drivers/cpufreq semaphores to mutexes.
Semaphore to mutex conversion.

The conversion was generated via scripts, and the result was validated
automatically via a script as well.

Signed-off-by: Arjan van de Ven <arjan@infradead.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Dave Jones <davej@redhat.com>
2006-01-18 13:53:45 -08:00
Alexander Clouter
001893cda2 [PATCH] cpufreq_conservative/ondemand: invert meaning of 'ignore nice'
The use of the 'ignore_nice' sysfs file is confusing to anyone using it.
This removes the sysfs file 'ignore_nice' and in its place creates a
'ignore_nice_load' entry that defaults to '0'; meaning nice'd processes
_are_ counted towards the 'business' calculation.

WARNING: this obvious breaks any userland tools that expected ignore_nice'
to exist, to draw attention to this fact it was concluded on the mailing
list that the entry should be removed altogether so the userland app breaks
and so the author can build simple to detect workaround.  Having said that
it seems currently very few tools even make use of this functionality; all
I could find was a Gentoo Wiki entry.

Signed-off-by: Alexander Clouter <alex-kernel@digriz.org.uk>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Dave Jones <davej@redhat.com>
2005-12-01 01:23:23 -08:00
Dave Jones
df8b59be09 [CPUFREQ] Avoid the ondemand cpufreq governor to use a too high frequency for stats.
The problem is in the ondemand governor, there is a periodic measurement
of the CPU usage. This CPU usage is updated by the scheduler after every
tick (basically, by adding 1 either to "idle" or to "user" or to
"system"). So if the frequency of the governor is too high, the stat
will be meaningless (as mostly no number have changed).

So this patch checks that the measurements are separated by at least 10
ticks. It means that by default, stats will have about 5% error (20
ticks). Of course those numbers can be argued but, IMHO, they look sane.
The patch also includes a small clean-up to check more explictly the
result of the conversion from ns to µs being null.

Let's note that (on x86) this has never been really needed before 2.6.13
because HZ was always 1000. Now that HZ can be 100, some CPU might be
affected by this problem. For instance when HZ=100, the centrino ,which
has a 10µs transition latency, would lead to the governor allowing to
read stats every tick (10ms)!

Signed-off-by: Eric Piel <eric.piel@tremplin-utc.net>
Signed-off-by: Dave Jones <davej@redhat.com>
2005-09-20 12:39:35 -07:00
Dave Jones
e131832ca7 [CPUFREQ] ondemand governor default sampling downfactor as 1
[PATCH] [5/5] ondemand governor default sampling downfactor as 1

Make default sampling downfactor 1.
This works better with earlier auto downscaling change in ondemand governor.

Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Dave Jones <davej@redhat.com>
2005-05-31 19:03:50 -07:00
Dave Jones
c29f140309 [CPUFREQ] ondemand governor automatic downscaling
[PATCH] [4/5] ondemand governor automatic downscaling

Here is a change of policy for the ondemand governor. The modification
concerns the frequency downscaling. Instead of decreasing to a lower
frequency when the CPU usage is under 20%, this new policy automatically
scales to the optimal frequency. The optimal frequency being the lowest
frequency which provides enough power to not trigger the upscaling policy.

Signed-off-by: Eric Piel <eric.piel@tremplin-utc.net>
Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Dave Jones <davej@redhat.com>
2005-05-31 19:03:50 -07:00
Dave Jones
9c7d269b9b [CPUFREQ] ondemand,conservative governor idle_tick clean-up
[PATCH] [3/5] ondemand,conservative governor idle_tick clean-up

Ondemand and conservative governor clean-up, it factorises the idle ticks 
measurement.

Signed-off-by: Eric Piel <eric.piel@tremplin-utc.net>
Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Dave Jones <davej@redhat.com>
2005-05-31 19:03:49 -07:00
Dave Jones
790d76fa97 [CPUFREQ] ondemand,conservative governor store the idle ticks for all cpus
[PATCH] [2/5] ondemand,conservative governor store the idle ticks for all cpus

Ondemand, conservative governor did not store prev_cpu_idle_up into 
prev_cpu_idle_down for other CPUs than the current CPU.

Signed-off-by: Eric Piel <eric.piel@tremplin-utc.net>
Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Dave Jones <davej@redhat.com>
2005-05-31 19:03:49 -07:00
Dave Jones
dac1c1a562 [CPUFREQ] ondemand,conservative minor bug-fix and cleanup
[PATCH] [1/5] ondemand,conservative minor bug-fix and cleanup

Attached patch fixes some minor issues with Alexander's patch and related
cleanup in both ondemand and conservative governor.

Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Dave Jones <davej@redhat.com>
2005-05-31 19:03:49 -07:00
Dave Jones
1206aaac28 [CPUFREQ] Allow ondemand stepping to be changed by user.
Adds support so that the cpufreq change stepping is no longer fixed at 5% and
can be changed dynamically by the user

Signed-off-by: Alexander Clouter <alex-kernel@digriz.org.uk>
Signed-off-by: Dave Jones <davej@redhat.com>
2005-05-31 19:03:48 -07:00
Dave Jones
c11420a616 [CPUFREQ] Prevents un-necessary cpufreq changes if we are already at min/max
Signed-off-by: Alexander Clouter <alex-kernel@digriz.org.uk>
Signed-off-by: Dave Jones <davej@redhat.com>
2005-05-31 19:03:48 -07:00
Dave Jones
3d5ee9e55d [CPUFREQ] Add support to cpufreq_ondemand to ignore 'nice' cpu time
Signed-off-by: Alexander Clouter <alex-kernel@digriz.org.uk>
Signed-off-by: Dave Jones <davej@redhat.com>
2005-05-31 19:03:47 -07:00
Dave Jones
7f335d4ef2 [CPUFREQ] make cpufreq_gov_dbs static
This patch makes a needlessly global and EXPORT_SYMBOL'ed struct static.

Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Dave Jones <davej@redhat.com>
2005-05-31 19:03:46 -07:00
Dave Jones
6fe711658f [CPUFREQ] ondemand: trivial clean-ups
Trivial ondemand governor clean-ups:
- change from sampling_rate_in_HZ() to the official function
usecs_to_jiffies().
- use for_each_online_cpu() to instead of using "if (cpu_online(i))"

Signed-off-by: Eric Piel <eric.piel@tremplin-utc.net>
Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Dave Jones <davej@redhat.com>
2005-05-31 19:03:44 -07:00
Linus Torvalds
1da177e4c3 Linux-2.6.12-rc2
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!
2005-04-16 15:20:36 -07:00