linux-toradex.git/kernel/tsacct.c, branch v4.10-rc5

time, acct: Drop irq save & restore from __acct_update_integrals()

2016-02-29T08:53:09+00:00

It looks like all the call paths that lead to __acct_update_integrals()
already have irqs disabled, and __acct_update_integrals() does not need
to disable irqs itself.

This is very convenient since about half the CPU time left in this
function was spent in local_irq_save alone.

Performance of a microbenchmark that calls an invalid syscall
ten million times in a row on a nohz_full CPU improves 21% vs.
4.5-rc1 with both the removal of divisions from __acct_update_integrals()
and this patch, with runtime dropping from 3.7 to 2.9 seconds.

With these patches applied, the highest remaining cpu user in
the trace is native_sched_clock, which is addressed in the next
patch.

For testing purposes I stuck a WARN_ON(!irqs_disabled()) test
in __acct_update_integrals(). It did not trigger.

Suggested-by: Peter Zijlstra 
Signed-off-by: Rik van Riel 
Signed-off-by: Peter Zijlstra (Intel) 
Reviewed-by: Thomas Gleixner 
Cc: Linus Torvalds 
Cc: Mike Galbraith 
Cc: clark@redhat.com
Cc: eric.dumazet@gmail.com
Cc: fweisbec@gmail.com
Cc: luto@amacapital.net
Link: http://lkml.kernel.org/r/1455152907-18495-4-git-send-email-riel@redhat.com
Signed-off-by: Ingo Molnar

acct, time: Change indentation in __acct_update_integrals()

2016-02-29T08:53:09+00:00

Change the indentation in __acct_update_integrals() to make the function
a little easier to read.

Suggested-by: Peter Zijlstra 
Signed-off-by: Rik van Riel 
Signed-off-by: Peter Zijlstra (Intel) 
Reviewed-by: Thomas Gleixner 
Acked-by: Frederic Weisbecker 
Cc: Linus Torvalds 
Cc: Mike Galbraith 
Cc: clark@redhat.com
Cc: eric.dumazet@gmail.com
Cc: fweisbec@gmail.com
Cc: luto@amacapital.net
Link: http://lkml.kernel.org/r/1455152907-18495-3-git-send-email-riel@redhat.com
Signed-off-by: Ingo Molnar

sched, time: Remove non-power-of-two divides from __acct_update_integrals()

2016-02-29T08:53:08+00:00

When running a microbenchmark calling an invalid syscall number
in a loop, on a nohz_full CPU, we spend a full 9% of our CPU
time in __acct_update_integrals().

This function converts cputime_t to jiffies, to a timeval, only to
convert the timeval back to microseconds before discarding it.

This patch leaves __acct_update_integrals() functionally equivalent,
but speeds things up by about 12%, with 10 million calls to an
invalid syscall number dropping from 3.7 to 3.25 seconds.

Signed-off-by: Rik van Riel 
Signed-off-by: Peter Zijlstra (Intel) 
Reviewed-by: Thomas Gleixner 
Cc: Linus Torvalds 
Cc: Mike Galbraith 
Cc: Peter Zijlstra 
Cc: clark@redhat.com
Cc: eric.dumazet@gmail.com
Cc: fweisbec@gmail.com
Cc: luto@amacapital.net
Link: http://lkml.kernel.org/r/1455152907-18495-2-git-send-email-riel@redhat.com
Signed-off-by: Ingo Molnar

sched: Make task->start_time nanoseconds based

2014-07-23T17:18:05+00:00

Simplify the timespec to nsec/usec conversions.

Signed-off-by: Thomas Gleixner 
Signed-off-by: John Stultz

tsacct: Use ktime_get_ts()

2014-06-12T14:18:45+00:00

do_posix_clock_monotonic_gettime() is a leftover from the initial
posix timer implementation which maps to ktime_get_ts()

Signed-off-by: Thomas Gleixner 
Cc: John Stultz 
Cc: Peter Zijlstra 
Link: http://lkml.kernel.org/r/20140611234606.840900621@linutronix.de
Signed-off-by: Thomas Gleixner

cputime: Use accessors to read task cputime stats

2013-01-27T18:23:31+00:00

This is in preparation for the full dynticks feature. While
remotely reading the cputime of a task running in a full
dynticks CPU, we'll need to do some extra-computation. This
way we can account the time it spent tickless in userspace
since its last cputime snapshot.

Signed-off-by: Frederic Weisbecker 
Cc: Andrew Morton 
Cc: Ingo Molnar 
Cc: Li Zhong 
Cc: Namhyung Kim 
Cc: Paul E. McKenney 
Cc: Paul Gortmaker 
Cc: Peter Zijlstra 
Cc: Steven Rostedt 
Cc: Thomas Gleixner

userns: Convert taskstats to handle the user and pid namespaces.

2012-09-18T08:01:32+00:00

- Explicitly limit exit task stat broadcast to the initial user and
  pid namespaces, as it is already limited to the initial network
  namespace.

- For broadcast task stats explicitly generate all of the idenitiers
  in terms of the initial user namespace and the initial pid
  namespace.

- For request stats report them in terms of the current user namespace
  and the current pid namespace.  Netlink messages are delivered
  syncrhonously to the kernel allowing us to get the user namespace
  and the pid namespace from the current task.

- Pass the namespaces for representing pids and uids and gids
  into bacct_add_task.

Cc: Balbir Singh 
Signed-off-by: Eric W. Biederman

[S390] cputime: add sparse checking and cleanup

2011-12-15T13:56:19+00:00

Make cputime_t and cputime64_t nocast to enable sparse checking to
detect incorrect use of cputime. Drop the cputime macros for simple
scalar operations. The conversion macros are still needed.

Signed-off-by: Martin Schwidefsky

Make taskstats round statistics down to nearest 1k bytes/events

2011-09-20T00:10:57+00:00

Even with just the interface limited to admin, there really is little to
reason to give byte-per-byte counts for taskstats.  So round it down to
something less intrusive.

Acked-by: Balbir Singh 
Signed-off-by: Linus Torvalds

taskstats: use real microsecond granularity for CPU times

2010-10-28T01:03:17+00:00

The taskstats interface uses microsecond granularity for the user and
system time values.  The conversion from cputime to the taskstats values
uses the cputime_to_msecs primitive which effectively limits the
granularity to milliseconds.  Add the cputime_to_usecs primitive for
architectures that have better, more precise CPU time values.  Remove
cputime_to_msecs primitive because there are no more users left.

Signed-off-by: Michael Holzheu 
Acked-by: Balbir Singh 
Cc: Luck Tony 
Cc: Shailabh Nagar 
Cc: Martin Schwidefsky 
Cc: Oleg Nesterov 
Cc: Benjamin Herrenschmidt 
Cc: Heiko Carstens 
Cc: Thomas Gleixner 
Cc: Shailabh Nagar 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds