From 21ef97f05a7da5bc23b26cb34d6746f83ca9bf20 Mon Sep 17 00:00:00 2001 From: Ian Munsie Date: Fri, 10 Dec 2010 14:09:16 +1100 Subject: perf session: Fallback to unordered processing if no sample_id_all If we are running the new perf on an old kernel without support for sample_id_all, we should fall back to the old unordered processing of events. If we didn't than we would *always* process events without timestamps out of order, whether or not we hit a reordering race. In other words, instead of there being a chance of not attributing samples correctly, we would guarantee that samples would not be attributed. While processing all events without timestamps before events with timestamps may seem like an intuitive solution, it falls down as PERF_RECORD_EXIT events would also be processed before any samples. Even with a workaround for that case, samples before/after an exec would not be attributed correctly. This patch allows commands to indicate whether they need to fall back to unordered processing, so that commands that do not care about timestamps on every event will not be affected. If we do fallback, this will print out a warning if report -D was invoked. This patch adds the test in perf_session__new so that we only need to test once per session. Commands that do not use an event_ops (such as record and top) can simply pass NULL in it's place. Acked-by: Thomas Gleixner Cc: Frederic Weisbecker Cc: Ingo Molnar Cc: Peter Zijlstra Cc: Thomas Gleixner LKML-Reference: <1291951882-sup-6069@au1.ibm.com> Signed-off-by: Ian Munsie Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/builtin-kmem.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'tools/perf/builtin-kmem.c') diff --git a/tools/perf/builtin-kmem.c b/tools/perf/builtin-kmem.c index c9620ff6496f..def7ddc2fd4f 100644 --- a/tools/perf/builtin-kmem.c +++ b/tools/perf/builtin-kmem.c @@ -481,7 +481,8 @@ static void sort_result(void) static int __cmd_kmem(void) { int err = -EINVAL; - struct perf_session *session = perf_session__new(input_name, O_RDONLY, 0, false); + struct perf_session *session = perf_session__new(input_name, O_RDONLY, + 0, false, &event_ops); if (session == NULL) return -ENOMEM; -- cgit v1.2.2