linux/include
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
..
acpi Merge branches 'acpi-processor' and 'acpi-cppc' 2016-03-14 14:20:33 +01:00
asm-generic arch, ftrace: for KASAN put hard/soft IRQ entries into separate sections 2016-03-25 16:37:42 -07:00
clocksource
crypto Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security 2016-03-17 11:33:45 -07:00
drm drm/ttm: use phys_addr_t for ttm_bus_placement 2016-04-04 17:00:01 -04:00
dt-bindings The clk changes for this release cycle are mostly dominated by 2016-03-23 06:06:45 -07:00
keys
kvm arm64: KVM: vgic-v3: Avoid accessing ICH registers 2016-03-09 04:24:04 +00:00
linux perf core: Allow setting up max frame stack depth via sysctl 2016-04-27 10:20:39 -03:00
math-emu
media Merge branch 'for-linus' of git://ftp.arm.linux.org.uk/~rmk/linux-arm 2016-03-19 16:31:54 -07:00
memory
misc cxl: Remove cxl_get_phys_dev() kernel API 2016-03-09 23:40:02 +11:00
net For the current RC series, we have the following fixes: 2016-04-08 16:41:28 -04:00
pcmcia
ras
rdma Round two of 4.6 merge window patches 2016-03-22 15:48:44 -07:00
rxrpc rxrpc: Be more selective about the types of received packets we accept 2016-03-04 15:56:06 +00:00
scsi Merge branch 'fixes-base' into fixes 2016-04-05 06:56:47 -04:00
soc IOMMU Updates for Linux v4.6 2016-03-22 11:57:43 -07:00
sound ASoC: Updates for v4.6 2016-03-14 14:03:29 +01:00
target target: add a new add_wwn_groups fabrics method 2016-03-30 20:06:44 -07:00
trace Merge branch 'for-linus-4.6' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs 2016-04-09 10:41:34 -07:00
uapi perf/core: Add ::write_backward attribute to perf event 2016-04-23 14:12:39 +02:00
video gpu: ipu-v3: ipu-dmfc: Rename ipu_dmfc_init_channel to ipu_dmfc_config_wait4eot 2016-03-31 11:24:33 +02:00
xen xen-netback: re-import canonical netif header 2016-03-13 22:08:01 -04:00
Kbuild