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Jiri Olsa ab0cce560e Revert "sched, perf: Use a single callback into the scheduler" 
This reverts commit cb04ff9ac4 ("sched, perf: Use a single
callback into the scheduler").

Before this change was introduced, the process switch worked
like this (wrt. to perf event schedule):

     schedule (prev, next)
       - schedule out all perf events for prev
       - switch to next
       - schedule in all perf events for current (next)

After the commit, the process switch looks like:

     schedule (prev, next)
       - schedule out all perf events for prev
       - schedule in all perf events for (next)
       - switch to next

The problem is, that after we schedule perf events in, the pmu
is enabled and we can receive events even before we make the
switch to next - so "current" still being prev process (event
SAMPLE data are filled based on the value of the "current"
process).

Thats exactly what we see for test__PERF_RECORD test. We receive
SAMPLES with PID of the process that our tracee is scheduled
from.

Discussed with Peter Zijlstra:

 > Bah!, yeah I guess reverting is the right thing for now. Sad
 > though.
 >
 > So by having the two hooks we have a black-spot between them
 > where we receive no events at all, this black-spot covers the
 > hand-over of current and we thus don't receive the 'wrong'
 > events.
 >
 > I rather liked we could do away with both that black-spot and
 > clean up the code a little, but apparently people rely on it.

Signed-off-by: Jiri Olsa <jolsa@redhat.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: acme@redhat.com
Cc: paulus@samba.org
Cc: cjashfor@linux.vnet.ibm.com
Cc: fweisbec@gmail.com
Cc: eranian@google.com
Link: http://lkml.kernel.org/r/20120523111302.GC1638@m.brq.redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2012-05-23 17:40:51 +02:00
..
auto_group.c sched: Clean up parameter passing of proc_sched_autogroup_set_nice() 2012-03-02 12:23:49 +01:00
auto_group.h
clock.c
core.c Revert "sched, perf: Use a single callback into the scheduler" 2012-05-23 17:40:51 +02:00
cpupri.c kernel-doc: fix kernel-doc warnings in sched 2012-01-23 08:44:54 -08:00
cpupri.h
debug.c sched: Remove sched_switch 2012-01-27 13:28:53 +01:00
fair.c sched: Fix more load-balancing fallout 2012-04-26 12:54:52 +02:00
features.h sched: Fix more load-balancing fallout 2012-04-26 12:54:52 +02:00
idle_task.c
Makefile
rt.c sched/rt: Improve pick_next_highest_task_rt() 2012-03-27 14:52:12 +02:00
sched.h Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2012-03-31 13:35:31 -07:00
stats.c sched: Remove sched_switch 2012-01-27 13:28:53 +01:00
stats.h
stop_task.c