From f3e459d16a8493b617ccf2a940330279679e0291 Mon Sep 17 00:00:00 2001 From: Arnaldo Carvalho de Melo Date: Fri, 15 Apr 2016 17:52:34 -0300 Subject: [PATCH] perf trace: Bump --mmap-pages when --call-graph is used by the root user To reduce the chances we'll overflow the mmap buffer, manual fine tuning trumps this. Cc: Adrian Hunter Cc: David Ahern Cc: Jiri Olsa Cc: Milian Wolff Cc: Namhyung Kim Cc: Wang Nan Link: http://lkml.kernel.org/n/tip-wxygbxmp1v9mng1ea28wet02@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo --- 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); -- 2.20.1