From: Arnaldo Carvalho de Melo <[email protected]> To reduce the chances we'll overflow the mmap buffer, manual fine tuning trumps this.
Cc: Adrian Hunter <[email protected]> Cc: David Ahern <[email protected]> Cc: Jiri Olsa <[email protected]> Cc: Milian Wolff <[email protected]> Cc: Namhyung Kim <[email protected]> Cc: Wang Nan <[email protected]> Link: http://lkml.kernel.org/n/[email protected] Signed-off-by: Arnaldo Carvalho de Melo <[email protected]> --- tools/perf/Documentation/perf-trace.txt | 4 ++++ tools/perf/builtin-trace.c | 10 +++++++++- 2 files changed, 13 insertions(+), 1 deletion(-) diff --git a/tools/perf/Documentation/perf-trace.txt b/tools/perf/Documentation/perf-trace.txt index 146c6db21cbf..c075c002eaa4 100644 --- a/tools/perf/Documentation/perf-trace.txt +++ b/tools/perf/Documentation/perf-trace.txt @@ -123,6 +123,10 @@ the thread executes on the designated CPUs. Default is to monitor all CPUs. man pages for details. The ones that are most useful in 'perf trace' are 'dwarf' and 'lbr', where available, try: 'perf trace --call-graph dwarf'. + Using this will, for the root user, bump the value of --mmap-pages to 4 + times the maximum for non-root users, based on the kernel.perf_event_mlock_kb + sysctl. This is done only if the user doesn't specify a --mmap-pages value. + --kernel-syscall-graph:: Show the kernel callchains on the syscall exit path. diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c index 19f5100acc1d..026ec0c749b0 100644 --- a/tools/perf/builtin-trace.c +++ b/tools/perf/builtin-trace.c @@ -3110,6 +3110,7 @@ int cmd_trace(int argc, const char **argv, const char *prefix __maybe_unused) OPT_END() }; bool max_stack_user_set = true; + bool mmap_pages_user_set = true; const char * const trace_subcommands[] = { "record", NULL }; int err; char bf[BUFSIZ]; @@ -3143,6 +3144,9 @@ int cmd_trace(int argc, const char **argv, const char *prefix __maybe_unused) trace.opts.sample_time = true; } + if (trace.opts.mmap_pages == UINT_MAX) + mmap_pages_user_set = false; + if (trace.max_stack == UINT_MAX) { trace.max_stack = PERF_MAX_STACK_DEPTH; max_stack_user_set = false; @@ -3153,8 +3157,12 @@ int cmd_trace(int argc, const char **argv, const char *prefix __maybe_unused) record_opts__parse_callchain(&trace.opts, &callchain_param, "dwarf", false); #endif - if (trace.opts.callgraph_set) + if (trace.opts.callgraph_set) { + if (!mmap_pages_user_set && geteuid() == 0) + trace.opts.mmap_pages = perf_event_mlock_kb_in_pages() * 4; + symbol_conf.use_callchain = true; + } if (trace.evlist->nr_entries > 0) evlist__set_evsel_handler(trace.evlist, trace__event_handler); -- 2.5.5
