Arnaldo Carvalho de Melo c5dfd78eb7 perf core: Allow setting up max frame stack depth via sysctl ... The default remains 127, which is good for most cases, and not even hit most of the time, but then for some cases, as reported by Brendan, 1024+ deep frames are appearing on the radar for things like groovy, ruby. And in some workloads putting a _lower_ cap on this may make sense. One that is per event still needs to be put in place tho. The new file is: # cat /proc/sys/kernel/perf_event_max_stack 127 Chaging it: # echo 256 > /proc/sys/kernel/perf_event_max_stack # cat /proc/sys/kernel/perf_event_max_stack 256 But as soon as there is some event using callchains we get: # echo 512 > /proc/sys/kernel/perf_event_max_stack -bash: echo: write error: Device or resource busy # Because we only allocate the callchain percpu data structures when there is a user, which allows for changing the max easily, its just a matter of having no callchain users at that point. Reported-and-Tested-by: Brendan Gregg <brendan.d.gregg@gmail.com> Reviewed-by: Frederic Weisbecker <fweisbec@gmail.com> Acked-by: Alexei Starovoitov <ast@kernel.org> Acked-by: David Ahern <dsahern@gmail.com> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: He Kuang <hekuang@huawei.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Milian Wolff <milian.wolff@kdab.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephane Eranian <eranian@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vince Weaver <vincent.weaver@maine.edu> Cc: Wang Nan <wangnan0@huawei.com> Cc: Zefan Li <lizefan@huawei.com> Link: http://lkml.kernel.org/r/20160426002928.GB16708@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>		2016-04-27 10:20:39 -03:00
..
arraymap.c	bpf: check for reserved flag bits in array and stack maps	2016-03-08 15:28:31 -05:00
core.c	bpf: Mark __bpf_prog_run() stack frame as non-standard	2016-02-29 08:35:11 +01:00
hashtab.c	bpf: pre-allocate hash map elements	2016-03-08 15:28:31 -05:00
helpers.c	bpf: avoid copying junk bytes in bpf_get_current_comm()	2016-03-09 23:27:30 -05:00
inode.c	bpf, inode: allow for rename and link ops	2015-12-12 18:44:23 -05:00
Makefile	bpf: introduce percpu_freelist	2016-03-08 15:28:31 -05:00
percpu_freelist.c	bpf: introduce percpu_freelist	2016-03-08 15:28:31 -05:00
percpu_freelist.h	bpf: introduce percpu_freelist	2016-03-08 15:28:31 -05:00
stackmap.c	perf core: Allow setting up max frame stack depth via sysctl	2016-04-27 10:20:39 -03:00
syscall.c	bpf: add missing map_flags to bpf_map_show_fdinfo	2016-03-25 11:36:41 -04:00
verifier.c	Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net	2016-02-23 00:09:14 -05:00