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perf tools: Set the maximum allowed stack from /proc/sys/kernel/perf_event_max_stack

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There is an upper limit to what tooling considers a valid callchain,
and it was tied to the hardcoded value in the kernel,
PERF_MAX_STACK_DEPTH (127), now that this can be tuned via a sysctl,
make it read it and use that as the upper limit, falling back to
PERF_MAX_STACK_DEPTH for kernels where this sysctl isn't present.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Brendan Gregg <brendan.d.gregg@gmail.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Milian Wolff <milian.wolff@kdab.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-yjqsd30nnkogvj5oyx9ghir9@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Arnaldo Carvalho de Melo
2016-04-27 10:16:24 -03:00
parent c5dfd78eb7
commit 4cb93446c5
16 changed files with 28 additions and 18 deletions
Download Patch File Download Diff File Expand all files Collapse all files

6
tools/perf/util/machine.c
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@@ -1764,7 +1764,7 @@ static int resolve_lbr_callchain_sample(struct thread *thread,
*/
int mix_chain_nr = i + 1 + lbr_nr + 1;
if (mix_chain_nr > PERF_MAX_STACK_DEPTH + PERF_MAX_BRANCH_DEPTH) {
if (mix_chain_nr > (int)sysctl_perf_event_max_stack + PERF_MAX_BRANCH_DEPTH) {
pr_warning("corrupted callchain. skipping...\n");
return 0;
}
@@ -1825,7 +1825,7 @@ static int thread__resolve_callchain_sample(struct thread *thread,
* Based on DWARF debug information, some architectures skip
* a callchain entry saved by the kernel.
*/
if (chain->nr < PERF_MAX_STACK_DEPTH)
if (chain->nr < sysctl_perf_event_max_stack)
skip_idx = arch_skip_callchain_idx(thread, chain);
/*
@@ -1886,7 +1886,7 @@ static int thread__resolve_callchain_sample(struct thread *thread,
}
check_calls:
if (chain->nr > PERF_MAX_STACK_DEPTH && (int)chain->nr > max_stack) {
if (chain->nr > sysctl_perf_event_max_stack && (int)chain->nr > max_stack) {
pr_warning("corrupted callchain. skipping...\n");
return 0;
}