linux.git/tools/perf/util/ordered-events.c, branch v3.19

perf session: Add option to copy events when queueing

2014-10-15T20:39:03+00:00

When processing events the session code has an ordered samples queue
which is used to time-sort events coming in across multiple mmaps. At a
later point in time samples on the queue are flushed up to some
timestamp at which point the event is actually processed.

When analyzing events live (ie., record/analysis path in the same
command) there is a race that leads to corrupted events and parse errors
which cause perf to terminate. The problem is that when the event is
placed in the ordered samples queue it is only a reference to the event
which is really sitting in the mmap buffer. Even though the event is
queued for later processing the mmap tail pointer is updated which
indicates to the kernel that the event has been processed. The race is
flushing the event from the queue before it gets overwritten by some
other event. For commands trying to process events live (versus just
writing to a file) and processing a high rate of events this leads to
parse failures and perf terminates.

Examples hitting this problem are 'perf kvm stat live', especially with
nested VMs which generate 100,000+ traces per second, and a command
processing scheduling events with a high rate of context switching --
e.g., running 'perf bench sched pipe'.

This patch offers live commands an option to copy the event when it is
placed in the ordered samples queue.

Based on a patch from David Ahern 

Signed-off-by: Alexander Yarygin 
Acked-by: Jiri Olsa 
Cc: Christian Borntraeger 
Cc: David Ahern 
Cc: Frederic Weisbecker 
Cc: Ingo Molnar 
Cc: Jiri Olsa 
Cc: Mike Galbraith 
Cc: Namhyung Kim 
Cc: Paul Mackerras 
Cc: Peter Zijlstra 
Cc: Stephane Eranian 
Link: http://lkml.kernel.org/r/1412347212-28237-2-git-send-email-yarygin@linux.vnet.ibm.com
Signed-off-by: Arnaldo Carvalho de Melo

perf tools: Allow out of order messages in forced flush

2014-08-12T15:03:02+00:00

In forced flush (OE_FLUSH__HALF) we break the rules of the flush
timestamp via PERF_RECORD_FINISHED_ROUND event, so we could get out of
order event.

Do not force error in this case plus changing the output warning to use
WARN_ONCE.

Signed-off-by: Jiri Olsa 
Acked-by: David Ahern 
Cc: Corey Ashford 
Cc: David Ahern 
Cc: Frederic Weisbecker 
Cc: Ingo Molnar 
Cc: Jean Pihet 
Cc: Namhyung Kim 
Cc: Paul Mackerras 
Cc: Peter Zijlstra 
Link: http://lkml.kernel.org/n/tip-8q8794a8nlmpd1u8xrqmcyd2@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo

perf tools: Add debug prints for ordered events queue

2014-08-12T15:03:01+00:00

Adding some prints for ordered events queue, to help debug issues.

Adding debug_ordered_events debug variable to be able to enable ordered
events debug messages using:

  $ perf --debug ordered-events=2 report ...

Also using oe pointer in perf_session__queue_event instead of chained
session variable dereferencing.

Signed-off-by: Jiri Olsa 
Acked-by: David Ahern 
Cc: Corey Ashford 
Cc: David Ahern 
Cc: Frederic Weisbecker 
Cc: Ingo Molnar 
Cc: Jean Pihet 
Cc: Namhyung Kim 
Cc: Paul Mackerras 
Cc: Peter Zijlstra 
Link: http://lkml.kernel.org/n/tip-7p3mnnopjvsp9nmk9msqcfkm@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo

perf tools: Add ordered_events__free function

2014-08-12T15:03:00+00:00

Adding ordered_events__free function to release all the struct
ordered_events data. It's replacement for former
perf_session_free_sample_buffers function.

Signed-off-by: Jiri Olsa 
Acked-by: David Ahern 
Cc: Corey Ashford 
Cc: David Ahern 
Cc: Frederic Weisbecker 
Cc: Ingo Molnar 
Cc: Jean Pihet 
Cc: Namhyung Kim 
Cc: Paul Mackerras 
Cc: Peter Zijlstra 
Link: http://lkml.kernel.org/n/tip-urraa8ccay4o14wambjraws7@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo

perf tools: Add ordered_events__init function

2014-08-12T15:02:59+00:00

Adding ordered_events__init function for struct ordered_events struct
initialization.

Signed-off-by: Jiri Olsa 
Acked-by: David Ahern 
Cc: Corey Ashford 
Cc: David Ahern 
Cc: Frederic Weisbecker 
Cc: Ingo Molnar 
Cc: Jean Pihet 
Cc: Namhyung Kim 
Cc: Paul Mackerras 
Cc: Peter Zijlstra 
Link: http://lkml.kernel.org/n/tip-g6dx35hed8g14eh1ygx4uzp6@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo

perf tools: Use list_move in ordered_events_delete function

2014-08-12T15:02:59+00:00

As Namhyung pointed out we can use list_move in ordered_events_delete.

Signed-off-by: Jiri Olsa 
Suggested-by: Namhyung Kim 
Acked-by: David Ahern 
Cc: Corey Ashford 
Cc: David Ahern 
Cc: Frederic Weisbecker 
Cc: Ingo Molnar 
Cc: Jean Pihet 
Cc: Namhyung Kim 
Cc: Paul Mackerras 
Cc: Peter Zijlstra 
Link: http://lkml.kernel.org/n/tip-m8ae5s5cuwyytitgb6iqilid@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo

perf tools: Create ordered-events object

2014-08-12T15:02:58+00:00

Move ordered events code into separated object ordered-events.[ch].

No functional change was intended.

Signed-off-by: Jiri Olsa 
Acked-by: David Ahern 
Cc: Corey Ashford 
Cc: David Ahern 
Cc: Frederic Weisbecker 
Cc: Ingo Molnar 
Cc: Jean Pihet 
Cc: Namhyung Kim 
Cc: Paul Mackerras 
Cc: Peter Zijlstra 
Link: http://lkml.kernel.org/n/tip-1ge3rilgudszbl87cejm1tfg@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo