Frederic Weisbecker c61e52ee70 perf: Generalize perf lock's sample event reordering to the session layer ... The sample events recorded by perf record are not time ordered because we have one buffer per cpu for each event (even demultiplexed per task/per cpu for task bound events). But when we read trace events we want them to be ordered by time because many state machines are involved. There are currently two ways perf tools deal with that: - use -M to multiplex every buffers (perf sched, perf kmem) But this creates a lot of contention in SMP machines on record time. - use a post-processing time reordering (perf timechart, perf lock) The reordering used by timechart is simple but doesn't scale well with huge flow of events, in terms of performance and memory use (unusable with perf lock for example). Perf lock has its own samples reordering that flushes its memory use in a regular basis and that uses a sorting based on the previous event queued (a new event to be queued is close to the previous one most of the time). This patch proposes to export perf lock's samples reordering facility to the session layer that reads the events. So if a tool wants to get ordered sample events, it needs to set its struct perf_event_ops::ordered_samples to true and that's it. This prepares tracing based perf tools to get rid of the need to use buffers multiplexing (-M) or to implement their own reordering. Also lower the flush period to 2 as it's sufficient already. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Hitoshi Mitake <mitake@dcl.info.waseda.ac.jp> Cc: Ingo Molnar <mingo@elte.hu> Cc: Masami Hiramatsu <mhiramat@redhat.com> Cc: Tom Zanussi <tzanussi@gmail.com>		2010-04-24 03:49:58 +02:00
..
perf	perf: Generalize perf lock's sample event reordering to the session layer	2010-04-24 03:49:58 +02:00