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perf core: Add a 'nr' field to perf_event_callchain_context

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We will use it to count how many addresses are in the entry->ip[] array,
excluding PERF_CONTEXT_{KERNEL,USER,etc} entries, so that we can really
return the number of entries specified by the user via the relevant
sysctl, kernel.perf_event_max_contexts, or via the per event
perf_event_attr.sample_max_stack knob.

This way we keep the perf_sample->ip_callchain->nr meaning, that is the
number of entries, be it real addresses or PERF_CONTEXT_ entries, while
honouring the max_stack knobs, i.e. the end result will be max_stack
entries if we have at least that many entries in a given stack trace.

Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/n/tip-s8teto51tdqvlfhefndtat9r@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Arnaldo Carvalho de Melo 2016-05-10 18:08:32 -03:00
parent cfbcf46845
commit 3b1fff0803
9 changed files with 18 additions and 17 deletions
Download patch file Download diff file Expand all files Collapse all files

4
arch/mips/kernel/perf_event.c
View file

@ -35,7 +35,7 @@ static void save_raw_perf_callchain(struct perf_callchain_entry_ctx *entry,
addr = *sp++;
if (__kernel_text_address(addr)) {
perf_callchain_store(entry, addr);
if (entry->entry->nr >= entry->max_stack)
if (entry->nr >= entry->max_stack)
break;
}
}
@ -59,7 +59,7 @@ void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry,
}
do {
perf_callchain_store(entry, pc);
if (entry->entry->nr >= entry->max_stack)
if (entry->nr >= entry->max_stack)
break;
pc = unwind_stack(current, &sp, pc, &ra);
} while (pc);