linux/arch/x86
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
..
boot x86/build: Build compressed x86 kernels as PIE 2016-03-29 12:51:12 +02:00
configs Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security 2016-03-17 11:33:45 -07:00
crypto Merge branch 'core-objtool-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-03-20 18:23:21 -07:00
entry Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-03-24 09:47:32 -07:00
events perf core: Allow setting up max frame stack depth via sysctl 2016-04-27 10:20:39 -03:00
ia32 Merge branch 'x86-headers-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2015-11-03 21:05:40 -08:00
include perf/x86/intel/rapl: Support Skylake RAPL domains 2016-04-23 14:13:36 +02:00
kernel Merge branch 'perf/urgent' into perf/core, to resolve conflict 2016-04-23 14:12:10 +02:00
kvm KVM: x86: mask CPUID(0xD,0x1).EAX against host value 2016-04-10 21:53:50 +02:00
lguest Merge branch 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-03-14 17:58:53 -07:00
lib Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-03-24 09:47:32 -07:00
math-emu Merge branch 'x86-headers-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2015-11-03 21:05:40 -08:00
mm mm/rmap: batched invalidations should use existing api 2016-04-01 17:03:37 -05:00
net x86/asm/bpf: Create stack frames in bpf_jit.S 2016-02-24 08:35:44 +01:00
oprofile Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-03-24 09:47:32 -07:00
pci PCI changes for the v4.6 merge window: 2016-03-16 14:45:55 -07:00
platform Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-03-24 09:47:32 -07:00
power x86/asm/power: Create stack frames in hibernate_asm_64.S 2016-02-24 08:35:43 +01:00
purgatory Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-03-24 09:47:32 -07:00
ras x86/topology: Fix AMD core count 2016-03-29 10:45:04 +02:00
realmode kernel: add kcov code coverage 2016-03-22 15:36:02 -07:00
tools
um Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2016-03-19 10:05:34 -07:00
video x86/video: Don't assume all FB devices are PCI devices 2016-03-15 11:08:26 +01:00
xen xen/x86: Call cpu_startup_entry(CPUHP_AP_ONLINE_IDLE) from xen_play_dead() 2016-03-29 09:34:10 -04:00
.gitignore
Kbuild perf/x86: Move perf_event.c ............... => x86/events/core.c 2016-02-09 10:23:49 +01:00
Kconfig Linux 4.6-rc3 2016-04-13 08:57:03 +02:00
Kconfig.cpu x86/Kconfig/cpus: Fix/complete CPU type help texts 2015-10-21 11:12:56 +02:00
Kconfig.debug Merge branch 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-03-15 09:32:27 -07:00
Makefile Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2015-11-04 09:11:12 -08:00
Makefile_32.cpu
Makefile.um