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  1. 19 10月, 2010 1 次提交
    • P
      irq_work: Add generic hardirq context callbacks · e360adbe
      由 Peter Zijlstra 提交于 
      Provide a mechanism that allows running code in IRQ context. It is
most useful for NMI code that needs to interact with the rest of the
system -- like wakeup a task to drain buffers.

Perf currently has such a mechanism, so extract that and provide it as
a generic feature, independent of perf so that others may also
benefit.

The IRQ context callback is generated through self-IPIs where
possible, or on architectures like powerpc the decrementer (the
built-in timer facility) is set to generate an interrupt immediately.

Architectures that don't have anything like this get to do with a
callback from the timer tick. These architectures can call
irq_work_run() at the tail of any IRQ handlers that might enqueue such
work (like the perf IRQ handler) to avoid undue latencies in
processing the work.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: NKyle McMartin <kyle@mcmartin.ca>
Acked-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>
[ various fixes ]
Signed-off-by: NHuang Ying <ying.huang@intel.com>
LKML-Reference: <1287036094.7768.291.camel@yhuang-dev>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      e360adbe
  3. 11 8月, 2010 1 次提交
  5. 04 8月, 2010 2 次提交
    • P
      timer: Added usleep_range timer · 5e7f5a17
      由 Patrick Pannuto 提交于 
      usleep_range is a finer precision implementations of msleep
and is designed to be a drop-in replacement for udelay where
a precise sleep / busy-wait is unnecessary.

Since an easy interface to hrtimers could lead to an undesired
proliferation of interrupts, we provide only a "range" API,
forcing the caller to think about an acceptable tolerance on
both ends and hopefully avoiding introducing another interrupt.

INTRO

As discussed here ( http://lkml.org/lkml/2007/8/3/250 ), msleep(1) is not
precise enough for many drivers (yes, sleep precision is an unfair notion,
but consistently sleeping for ~an order of magnitude greater than requested
is worth fixing). This patch adds a usleep API so that udelay does not have
to be used. Obviously not every udelay can be replaced (those in atomic
contexts or being used for simple bitbanging come to mind), but there are
many, many examples of

mydriver_write(...)
/* Wait for hardware to latch */
udelay(100)

in various drivers where a busy-wait loop is neither beneficial nor
necessary, but msleep simply does not provide enough precision and people
are using a busy-wait loop instead.

CONCERNS FROM THE RFC

Why is udelay a problem / necessary? Most callers of udelay are in device/
driver initialization code, which is serial...

	As I see it, there is only benefit to sleeping over a delay; the
	notion of "refactoring" areas that use udelay was presented, but
	I see usleep as the refactoring. Consider i2c, if the bus is busy,
	you need to wait a bit (say 100us) before trying again, your
	current options are:

		* udelay(100)
		* msleep(1) <-- As noted above, actually as high as ~20ms
				on some platforms, so not really an option
		* Manually set up an hrtimer to try again in 100us (which
		  is what usleep does anyway...)

	People choose the udelay route because it is EASY; we need to
	provide a better easy route.

	Device / driver / boot code is *currently* serial, but every few
	months someone makes noise about parallelizing boot, and IMHO, a
	little forward-thinking now is one less thing to worry about
	if/when that ever happens

udelay's could be preempted

	Sure, but if udelay plans on looping 1000 times, and it gets
	preempted on loop 200, whenever it's scheduled again, it is
	going to do the next 800 loops.

Is the interruptible case needed?

	Probably not, but I see usleep as a very logical parallel to msleep,
	so it made sense to include the "full" API. Processors are getting
	faster (albeit not as quickly as they are becoming more parallel),
	so if someone wanted to be interruptible for a few usecs, why not
	let them? If this is a contentious point, I'm happy to remove it.

OTHER THOUGHTS

I believe there is also value in exposing the usleep_range option; it gives
the scheduler a lot more flexibility and allows the programmer to express
his intent much more clearly; it's something I would hope future driver
writers will take advantage of.

To get the results in the NUMBERS section below, I literally s/udelay/usleep
the kernel tree; I had to go in and undo the changes to the USB drivers, but
everything else booted successfully; I find that extremely telling in and
of itself -- many people are using a delay API where a sleep will suit them
just fine.

SOME ATTEMPTS AT NUMBERS

It turns out that calculating quantifiable benefit on this is challenging,
so instead I will simply present the current state of things, and I hope
this to be sufficient:

How many udelay calls are there in 2.6.35-rc5?

	udealy(ARG) >=	| COUNT
	1000		| 319
	500		| 414
	100		| 1146
	20		| 1832

I am working on Android, so that is my focus for this. The following table
is a modified usleep that simply printk's the amount of time requested to
sleep; these tests were run on a kernel with udelay >= 20 --> usleep

"boot" is power-on to lock screen
"power collapse" is when the power button is pushed and the device suspends
"resume" is when the power button is pushed and the lock screen is displayed
         (no touchscreen events or anything, just turning on the display)
"use device" is from the unlock swipe to clicking around a bit; there is no
	sd card in this phone, so fail loading music, video, camera

	ACTION		| TOTAL NUMBER OF USLEEP CALLS	| NET TIME (us)
	boot		| 22				| 1250
	power-collapse	| 9				| 1200
	resume		| 5				| 500
	use device	| 59				| 7700

The most interesting category to me is the "use device" field; 7700us of
busy-wait time that could be put towards better responsiveness, or at the
least less power usage.
Signed-off-by: NPatrick Pannuto <ppannuto@codeaurora.org>
Cc: apw@canonical.com
Cc: corbet@lwn.net
Cc: arjan@linux.intel.com
Cc: Randy Dunlap <rdunlap@xenotime.net>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
      5e7f5a17
    • T
      Revert "timer: Added usleep[_range] timer" · e1b004c3
      由 Thomas Gleixner 提交于 
      This reverts commit 22b8f15c to merge
an advanced version.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
      e1b004c3
  7. 03 8月, 2010 1 次提交
  9. 23 7月, 2010 2 次提交
  11. 09 6月, 2010 1 次提交
    • V
      sched: Change nohz idle load balancing logic to push model · 83cd4fe2
      由 Venkatesh Pallipadi 提交于 
      In the new push model, all idle CPUs indeed go into nohz mode. There is
still the concept of idle load balancer (performing the load balancing
on behalf of all the idle cpu's in the system). Busy CPU kicks the nohz
balancer when any of the nohz CPUs need idle load balancing.
The kickee CPU does the idle load balancing on behalf of all idle CPUs
instead of the normal idle balance.

This addresses the below two problems with the current nohz ilb logic:
* the idle load balancer continued to have periodic ticks during idle and
  wokeup frequently, even though it did not have any rebalancing to do on
  behalf of any of the idle CPUs.
* On x86 and CPUs that have APIC timer stoppage on idle CPUs, this
  periodic wakeup can result in a periodic additional interrupt on a CPU
  doing the timer broadcast.

Also currently we are migrating the unpinned timers from an idle to the cpu
doing idle load balancing (when all the cpus in the system are idle,
there is no idle load balancing cpu and timers get added to the same idle cpu
where the request was made. So the existing optimization works only on semi idle
system).

And In semi idle system, we no longer have periodic ticks on the idle load
balancer CPU. Using that cpu will add more delays to the timers than intended
(as that cpu's timer base may not be uptodate wrt jiffies etc). This was
causing mysterious slowdowns during boot etc.

For now, in the semi idle case, use the nearest busy cpu for migrating timers
from an idle cpu.  This is good for power-savings anyway.
Signed-off-by: NVenkatesh Pallipadi <venki@google.com>
Signed-off-by: NSuresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Thomas Gleixner <tglx@linutronix.de>
LKML-Reference: <1274486981.2840.46.camel@sbs-t61.sc.intel.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      83cd4fe2
  13. 05 6月, 2010 1 次提交
  15. 28 5月, 2010 1 次提交
  17. 26 5月, 2010 2 次提交
    • T
      timers: Move local variable into else section · 2abfb9e1
      由 Thomas Gleixner 提交于 
      Fix nit-picking coding style detail.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
      2abfb9e1
    • T
      timers: Fix slack calculation really · 8e63d779
      由 Thomas Gleixner 提交于 
      commit f00e047e (timers: Fix slack calculation for expired timers)
fixed the issue of slack on expired timers only partially. Linus
noticed that jiffies is volatile so it is reloaded twice, which
generates bad code.

But its worse. This can defeat the time_after() check if jiffies are
incremented between time_after() and the slack calculation.

Fix it by reading jiffies into a local variable, which prevents the
compiler from loading it twice. While at it make the > -1 check into
>= 0 which is easier to read.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
      8e63d779
  19. 24 5月, 2010 1 次提交
  21. 13 5月, 2010 1 次提交
  23. 07 4月, 2010 1 次提交
    • A
      timers: Introduce the concept of timer slack for legacy timers · 3bbb9ec9
      由 Arjan van de Ven 提交于 
      While HR timers have had the concept of timer slack for quite some time
now, the legacy timers lacked this concept, and had to make do with
round_jiffies() and friends.

Timer slack is important for power management; grouping timers reduces the
number of wakeups which in turn reduces power consumption.

This patch introduces timer slack to the legacy timers using the following
pieces:
* A slack field in the timer struct
* An api (set_timer_slack) that callers can use to set explicit timer slack
* A default slack of 0.4% of the requested delay for callers that do not set
  any explicit slack
* Rounding code that is part of mod_timer() that tries to
  group timers around jiffies values every 'power of two'
  (so quick timers will group around every 2, but longer timers
  will group around every 4, 8, 16, 32 etc)
Signed-off-by: NArjan van de Ven <arjan@linux.intel.com>
Cc: johnstul@us.ibm.com
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
      3bbb9ec9
  25. 30 3月, 2010 1 次提交
    • T
      include cleanup: Update gfp.h and slab.h includes to prepare for breaking... · 5a0e3ad6
      由 Tejun Heo 提交于 
      include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h

percpu.h is included by sched.h and module.h and thus ends up being
included when building most .c files.  percpu.h includes slab.h which
in turn includes gfp.h making everything defined by the two files
universally available and complicating inclusion dependencies.

percpu.h -> slab.h dependency is about to be removed.  Prepare for
this change by updating users of gfp and slab facilities include those
headers directly instead of assuming availability.  As this conversion
needs to touch large number of source files, the following script is
used as the basis of conversion.

  http://userweb.kernel.org/~tj/misc/slabh-sweep.py

The script does the followings.

* Scan files for gfp and slab usages and update includes such that
  only the necessary includes are there.  ie. if only gfp is used,
  gfp.h, if slab is used, slab.h.

* When the script inserts a new include, it looks at the include
  blocks and try to put the new include such that its order conforms
  to its surrounding.  It's put in the include block which contains
  core kernel includes, in the same order that the rest are ordered -
  alphabetical, Christmas tree, rev-Xmas-tree or at the end if there
  doesn't seem to be any matching order.

* If the script can't find a place to put a new include (mostly
  because the file doesn't have fitting include block), it prints out
  an error message indicating which .h file needs to be added to the
  file.

The conversion was done in the following steps.

1. The initial automatic conversion of all .c files updated slightly
   over 4000 files, deleting around 700 includes and adding ~480 gfp.h
   and ~3000 slab.h inclusions.  The script emitted errors for ~400
   files.

2. Each error was manually checked.  Some didn't need the inclusion,
   some needed manual addition while adding it to implementation .h or
   embedding .c file was more appropriate for others.  This step added
   inclusions to around 150 files.

3. The script was run again and the output was compared to the edits
   from #2 to make sure no file was left behind.

4. Several build tests were done and a couple of problems were fixed.
   e.g. lib/decompress_*.c used malloc/free() wrappers around slab
   APIs requiring slab.h to be added manually.

5. The script was run on all .h files but without automatically
   editing them as sprinkling gfp.h and slab.h inclusions around .h
   files could easily lead to inclusion dependency hell.  Most gfp.h
   inclusion directives were ignored as stuff from gfp.h was usually
   wildly available and often used in preprocessor macros.  Each
   slab.h inclusion directive was examined and added manually as
   necessary.

6. percpu.h was updated not to include slab.h.

7. Build test were done on the following configurations and failures
   were fixed.  CONFIG_GCOV_KERNEL was turned off for all tests (as my
   distributed build env didn't work with gcov compiles) and a few
   more options had to be turned off depending on archs to make things
   build (like ipr on powerpc/64 which failed due to missing writeq).

   * x86 and x86_64 UP and SMP allmodconfig and a custom test config.
   * powerpc and powerpc64 SMP allmodconfig
   * sparc and sparc64 SMP allmodconfig
   * ia64 SMP allmodconfig
   * s390 SMP allmodconfig
   * alpha SMP allmodconfig
   * um on x86_64 SMP allmodconfig

8. percpu.h modifications were reverted so that it could be applied as
   a separate patch and serve as bisection point.

Given the fact that I had only a couple of failures from tests on step
6, I'm fairly confident about the coverage of this conversion patch.
If there is a breakage, it's likely to be something in one of the arch
headers which should be easily discoverable easily on most builds of
the specific arch.
Signed-off-by: NTejun Heo <tj@kernel.org>
Guess-its-ok-by: NChristoph Lameter <cl@linux-foundation.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
      5a0e3ad6
  27. 13 3月, 2010 4 次提交
  29. 21 1月, 2010 1 次提交
  31. 17 12月, 2009 1 次提交
  33. 21 9月, 2009 1 次提交
    • I
      perf: Do the big rename: Performance Counters -> Performance Events · cdd6c482
      由 Ingo Molnar 提交于 
      Bye-bye Performance Counters, welcome Performance Events!

In the past few months the perfcounters subsystem has grown out its
initial role of counting hardware events, and has become (and is
becoming) a much broader generic event enumeration, reporting, logging,
monitoring, analysis facility.

Naming its core object 'perf_counter' and naming the subsystem
'perfcounters' has become more and more of a misnomer. With pending
code like hw-breakpoints support the 'counter' name is less and
less appropriate.

All in one, we've decided to rename the subsystem to 'performance
events' and to propagate this rename through all fields, variables
and API names. (in an ABI compatible fashion)

The word 'event' is also a bit shorter than 'counter' - which makes
it slightly more convenient to write/handle as well.

Thanks goes to Stephane Eranian who first observed this misnomer and
suggested a rename.

User-space tooling and ABI compatibility is not affected - this patch
should be function-invariant. (Also, defconfigs were not touched to
keep the size down.)

This patch has been generated via the following script:

  FILES=$(find * -type f | grep -vE 'oprofile|[^K]config')

  sed -i \
    -e 's/PERF_EVENT_/PERF_RECORD_/g' \
    -e 's/PERF_COUNTER/PERF_EVENT/g' \
    -e 's/perf_counter/perf_event/g' \
    -e 's/nb_counters/nb_events/g' \
    -e 's/swcounter/swevent/g' \
    -e 's/tpcounter_event/tp_event/g' \
    $FILES

  for N in $(find . -name perf_counter.[ch]); do
    M=$(echo $N | sed 's/perf_counter/perf_event/g')
    mv $N $M
  done

  FILES=$(find . -name perf_event.*)

  sed -i \
    -e 's/COUNTER_MASK/REG_MASK/g' \
    -e 's/COUNTER/EVENT/g' \
    -e 's/\<event\>/event_id/g' \
    -e 's/counter/event/g' \
    -e 's/Counter/Event/g' \
    $FILES

... to keep it as correct as possible. This script can also be
used by anyone who has pending perfcounters patches - it converts
a Linux kernel tree over to the new naming. We tried to time this
change to the point in time where the amount of pending patches
is the smallest: the end of the merge window.

Namespace clashes were fixed up in a preparatory patch - and some
stylistic fallout will be fixed up in a subsequent patch.

( NOTE: 'counters' are still the proper terminology when we deal
  with hardware registers - and these sed scripts are a bit
  over-eager in renaming them. I've undone some of that, but
  in case there's something left where 'counter' would be
  better than 'event' we can undo that on an individual basis
  instead of touching an otherwise nicely automated patch. )
Suggested-by: NStephane Eranian <eranian@google.com>
Acked-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: NPaul Mackerras <paulus@samba.org>
Reviewed-by: NArjan van de Ven <arjan@linux.intel.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: David Howells <dhowells@redhat.com>
Cc: Kyle McMartin <kyle@mcmartin.ca>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: <linux-arch@vger.kernel.org>
LKML-Reference: <new-submission>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      cdd6c482
  35. 29 8月, 2009 1 次提交
  37. 26 8月, 2009 1 次提交
  39. 23 8月, 2009 1 次提交
    • P
      rcu: Simplify rcu_pending()/rcu_check_callbacks() API · a157229c
      由 Paul E. McKenney 提交于 
      All calls from outside RCU are of the form:

	if (rcu_pending(cpu))
		rcu_check_callbacks(cpu, user);

This is silly, instead we put a call to rcu_pending() in
rcu_check_callbacks(), and then make the outside calls be to
rcu_check_callbacks().  This cuts down on the code a bit and
also gives the compiler a better chance of optimizing.
Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: laijs@cn.fujitsu.com
Cc: dipankar@in.ibm.com
Cc: akpm@linux-foundation.org
Cc: mathieu.desnoyers@polymtl.ca
Cc: josht@linux.vnet.ibm.com
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: peterz@infradead.org
Cc: rostedt@goodmis.org
LKML-Reference: <125097461311-git-send-email->
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      a157229c
  41. 05 8月, 2009 1 次提交
    • M
      timers: Cache __next_timer_interrupt result · 97fd9ed4
      由 Martin Schwidefsky 提交于 
      Each time a cpu goes to sleep on a NOHZ=y system the timer
wheel is searched for the next timer interrupt. It can take
quite a few cycles to find the next pending timer.

This patch adds a field to tvec_base that caches the result of
__next_timer_interrupt.

The hit ratio is around 80% on my thinkpad under normal use, on
a server I've seen hit ratios from 5% to 95% dependent on the
workload.

-v2: jiffies wrap fixes
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>
Acked-by: NThomas Gleixner <tglx@linutronix.de>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Venki Pallipadi <venkatesh.pallipadi@intel.com>
LKML-Reference: <20090721202505.7d56a079@skybase>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      97fd9ed4
  43. 19 7月, 2009 1 次提交
  45. 24 6月, 2009 1 次提交
    • H
      timer stats: Optimize by adding quick check to avoid function calls · 507e1231
      由 Heiko Carstens 提交于 
      When the kernel is configured with CONFIG_TIMER_STATS but timer
stats are runtime disabled we still get calls to
__timer_stats_timer_set_start_info which initializes some
fields in the corresponding struct timer_list.

So add some quick checks in the the timer stats setup functions
to avoid function calls to __timer_stats_timer_set_start_info
when timer stats are disabled.

In an artificial workload that does nothing but playing ping
pong with a single tcp packet via loopback this decreases cpu
consumption by 1 - 1.5%.

This is part of a modified function trace output on SLES11:

 perl-2497  [00] 28630647177732388 [+  125]: sk_reset_timer <-tcp_v4_rcv
 perl-2497  [00] 28630647177732513 [+  125]: mod_timer <-sk_reset_timer
 perl-2497  [00] 28630647177732638 [+  125]: __timer_stats_timer_set_start_info <-mod_timer
 perl-2497  [00] 28630647177732763 [+  125]: __mod_timer <-mod_timer
 perl-2497  [00] 28630647177732888 [+  125]: __timer_stats_timer_set_start_info <-__mod_timer
 perl-2497  [00] 28630647177733013 [+   93]: lock_timer_base <-__mod_timer
Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Mustafa Mesanovic <mustafa.mesanovic@de.ibm.com>
Cc: Arjan van de Ven <arjan@infradead.org>
LKML-Reference: <20090623153811.GA4641@osiris.boeblingen.de.ibm.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      507e1231
  47. 29 5月, 2009 1 次提交
  49. 15 5月, 2009 2 次提交
    • T
      sched, timers: cleanup avenrun users · 2d02494f
      由 Thomas Gleixner 提交于 
      avenrun is an rough estimate so we don't have to worry about
consistency of the three avenrun values. Remove the xtime lock
dependency and provide a function to scale the values. Cleanup the
users.

[ Impact: cleanup ]
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Acked-by: NPeter Zijlstra <peterz@infradead.org>
      2d02494f
    • T
      sched, timers: move calc_load() to scheduler · dce48a84
      由 Thomas Gleixner 提交于 
      Dimitri Sivanich noticed that xtime_lock is held write locked across
calc_load() which iterates over all online CPUs. That can cause long
latencies for xtime_lock readers on large SMP systems. 

The load average calculation is an rough estimate anyway so there is
no real need to protect the readers vs. the update. It's not a problem
when the avenrun array is updated while a reader copies the values.

Instead of iterating over all online CPUs let the scheduler_tick code
update the number of active tasks shortly before the avenrun update
happens. The avenrun update itself is handled by the CPU which calls
do_timer().

[ Impact: reduce xtime_lock write locked section ]
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Acked-by: NPeter Zijlstra <peterz@infradead.org>
      dce48a84
  51. 13 5月, 2009 2 次提交
    • A
      timers: Logic to move non pinned timers · eea08f32
      由 Arun R Bharadwaj 提交于 
      * Arun R Bharadwaj <arun@linux.vnet.ibm.com> [2009-04-16 12:11:36]:

This patch migrates all non pinned timers and hrtimers to the current
idle load balancer, from all the idle CPUs. Timers firing on busy CPUs
are not migrated.

While migrating hrtimers, care should be taken to check if migrating
a hrtimer would result in a latency or not. So we compare the expiry of the
hrtimer with the next timer interrupt on the target cpu and migrate the
hrtimer only if it expires *after* the next interrupt on the target cpu.
So, added a clockevents_get_next_event() helper function to return the
next_event on the target cpu's clock_event_device.

[ tglx: cleanups and simplifications ]
Signed-off-by: NArun R Bharadwaj <arun@linux.vnet.ibm.com>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
      eea08f32
    • A
      timers: Framework for identifying pinned timers · 597d0275
      由 Arun R Bharadwaj 提交于 
      * Arun R Bharadwaj <arun@linux.vnet.ibm.com> [2009-04-16 12:11:36]:

This patch creates a new framework for identifying cpu-pinned timers
and hrtimers.

This framework is needed because pinned timers are expected to fire on
the same CPU on which they are queued. So it is essential to identify
these and not migrate them, in case there are any.

For regular timers, the currently existing add_timer_on() can be used
queue pinned timers and subsequently mod_timer_pinned() can be used
to modify the 'expires' field.

For hrtimers, new modes HRTIMER_ABS_PINNED and HRTIMER_REL_PINNED are
added to queue cpu-pinned hrtimer.

[ tglx: use .._PINNED mode argument instead of creating tons of new
functions ]
Signed-off-by: NArun R Bharadwaj <arun@linux.vnet.ibm.com>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
      597d0275
  53. 02 5月, 2009 1 次提交
  55. 06 4月, 2009 1 次提交
    • P
      perf_counter: unify and fix delayed counter wakeup · 925d519a
      由 Peter Zijlstra 提交于 
      While going over the wakeup code I noticed delayed wakeups only work
for hardware counters but basically all software counters rely on
them.

This patch unifies and generalizes the delayed wakeup to fix this
issue.

Since we're dealing with NMI context bits here, use a cmpxchg() based
single link list implementation to track counters that have pending
wakeups.

[ This should really be generic code for delayed wakeups, but since we
  cannot use cmpxchg()/xchg() in generic code, I've let it live in the
  perf_counter code. -- Eric Dumazet could use it to aggregate the
  network wakeups. ]

Furthermore, the x86 method of using TIF flags was flawed in that its
quite possible to end up setting the bit on the idle task, loosing the
wakeup.

The powerpc method uses per-cpu storage and does appear to be
sufficient.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: NPaul Mackerras <paulus@samba.org>
Orig-LKML-Reference: <20090330171023.153932974@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      925d519a
  57. 02 4月, 2009 1 次提交
    • R
      timers: add missing kernel-doc · 633fe795
      由 Randy Dunlap 提交于 
      Add missing kernel-doc parameter notation and change function
name to its new name:

  Warning(kernel/timer.c:543): No description found for parameter 'name'
  Warning(kernel/timer.c:543): No description found for parameter 'key'
Signed-off-by: NRandy Dunlap <randy.dunlap@oracle.com>
Cc: akpm <akpm@linux-foundation.org>
Cc: Johannes Berg <johannes@sipsolutions.net>
LKML-Reference: <20090401174723.f0bea0eb.randy.dunlap@oracle.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      633fe795
  59. 19 2月, 2009 1 次提交
    • I
      timers: add mod_timer_pending() · 74019224
      由 Ingo Molnar 提交于 
      Impact: new timer API

Based on an idea from Martin Josefsson with the help of
Patrick McHardy and Stephen Hemminger:

introduce the mod_timer_pending() API which is a mod_timer()
offspring that is an invariant on already removed timers.

(regular mod_timer() re-activates non-pending timers.)

This is useful for the networking code in that it can
allow unserialized mod_timer_pending() timer-forwarding
calls, but a single del_timer*() will stop the timer
from being reactivated again.

Also while at it:

- optimize the regular mod_timer() path some more, the
  timer-stat and a debug check was needlessly duplicated
  in __mod_timer().

- make the exports come straight after the function, as
  most other exports in timer.c already did.

- eliminate __mod_timer() as an external API, change the
  users to mod_timer().

The regular mod_timer() code path is not impacted
significantly, due to inlining optimizations and due to
the simplifications.

Based-on-patch-from: Stephen Hemminger <shemminger@vyatta.com>
Acked-by: NStephen Hemminger <shemminger@vyatta.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Patrick McHardy <kaber@trash.net>
Cc: netdev@vger.kernel.org
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      74019224
  61. 15 2月, 2009 1 次提交
  63. 14 1月, 2009 1 次提交