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  1. Feb 11, 2009
  3. Feb 06, 2009
  5. Feb 05, 2009
    • Peter Zijlstra's avatar
      timers: split process wide cpu clocks/timers · 4cd4c1b4
      Peter Zijlstra authored 
      

Change the process wide cpu timers/clocks so that we:

 1) don't mess up the kernel with too many threads,
 2) don't have a per-cpu allocation for each process,
 3) have no impact when not used.

In order to accomplish this we're going to split it into two parts:

 - clocks; which can take all the time they want since they run
           from user context -- ie. sys_clock_gettime(CLOCK_PROCESS_CPUTIME_ID)

 - timers; which need constant time sampling but since they're
           explicity used, the user can pay the overhead.

The clock readout will go back to a full sum of the thread group, while the
timers will run of a global 'clock' that only runs when needed, so only
programs that make use of the facility pay the price.

Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Reviewed-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      4cd4c1b4
    • Peter Zijlstra's avatar
      signal: re-add dead task accumulation stats. · 32bd671d
      Peter Zijlstra authored 
      We're going to split the process wide cpu accounting into two parts:

 - clocks; which can take all the time they want since they run
           from user context.

 - timers; which need constant time tracing but can affort the overhead
           because they're default off -- and rare.

The clock readout will go back to a full sum of the thread group, for this
we need to re-add the exit stats that were removed in the initial itimer
rework (f06febc9

: timers: fix itimer/many thread hang).

Furthermore, since that full sum can be rather slow for large thread groups
and we have the complete dead task stats, revert the do_notify_parent time
computation.

Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Reviewed-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      32bd671d
    • Ingo Molnar's avatar
      Merge branch 'sched/urgent' into timers/urgent · 83895147
      Ingo Molnar authored 
      

Merging it here because an upcoming timers/urgent fix relies on
a change already in sched/urgent and not yet upstream.

Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      83895147
    • Pavel Emelyanov's avatar
      x86: fix hpet timer reinit for x86_64 · a6a95406
      Pavel Emelyanov authored 
      

There's a small problem with hpet_rtc_reinit function - it checks
for the:

	hpet_readl(HPET_COUNTER) - hpet_t1_cmp > 0

to continue increasing both the HPET_T1_CMP (register) and the
hpet_t1_cmp (variable).

But since the HPET_COUNTER is always 32-bit, if the hpet_t1_cmp
is 64-bit this condition will always be FALSE once the latter hits
the 32-bit boundary, and we can have a situation, when we don't
increase the HPET_T1_CMP register high enough.

The result - timer stops ticking, since HPET_T1_CMP becomes less,
than the COUNTER and never increased again.

The solution is (based on Linus's suggestion) to not compare 64-bits
(on 64-bit x86), but to do the comparison on 32-bit signed
integers.

Reported-by: default avatarKirill Korotaev <dev@openvz.org>
Signed-off-by: default avatarPavel Emelyanov <xemul@openvz.org>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      a6a95406
    • Suresh Siddha's avatar
      sched: fix nohz load balancer on cpu offline · 483b4ee6
      Suresh Siddha authored 
      

Christian Borntraeger reports:

> After a logical cpu offline, even on a complete idle system, there
> is one cpu with full ticks. It turns out that nohz.cpu_mask has the
> the offlined cpu still set.
>
> In select_nohz_load_balancer() we check if the system is completely
> idle to turn of load balancing. We compare cpu_online_map with
> nohz.cpu_mask.  Since cpu_online_map is updated on cpu unplug,
> but nohz.cpu_mask is not, the check fails and the scheduler believes
> that we need an "idle load balancer" even on a fully idle system.
> Since the ilb cpu does not deactivate the timer tick this breaks NOHZ.

Fix the select_nohz_load_balancer() to not set the nohz.cpu_mask
while a cpu is going offline.

Reported-by: default avatarChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: default avatarSuresh Siddha <suresh.b.siddha@intel.com>
Tested-by: default avatarChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      483b4ee6
  7. Feb 03, 2009
  9. Feb 02, 2009