diff options
author | Peter Zijlstra <peterz@infradead.org> | 2016-03-17 15:17:35 +0100 |
---|---|---|
committer | Ingo Molnar <mingo@kernel.org> | 2016-03-21 09:08:17 +0100 |
commit | 91a612eea9a316c464cc170ff8492ec09e7d1c69 (patch) | |
tree | 206ff774df73c92cf24196aca96e6eb325aaa9b6 /kernel/events/ring_buffer.c | |
parent | c2872d381f1ab1bc39c7f044644bf1d3da7c11dd (diff) | |
download | op-kernel-dev-91a612eea9a316c464cc170ff8492ec09e7d1c69.zip op-kernel-dev-91a612eea9a316c464cc170ff8492ec09e7d1c69.tar.gz |
perf/core: Fix dynamic interrupt throttle
There were two problems with the dynamic interrupt throttle mechanism,
both triggered by the same action.
When you (or perf_fuzzer) write a huge value into
/proc/sys/kernel/perf_event_max_sample_rate the computed
perf_sample_allowed_ns becomes 0. This effectively disables the whole
dynamic throttle.
This is fixed by ensuring update_perf_cpu_limits() never sets the
value to 0. However, we allow disabling of the dynamic throttle by
writing 100 to /proc/sys/kernel/perf_cpu_time_max_percent. This will
generate a warning in dmesg.
The second problem is that by setting the max_sample_rate to a huge
number, the adaptive process can take a few tries, since it halfs the
limit each time. Change that to directly compute a new value based on
the observed duration.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
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>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/events/ring_buffer.c')
0 files changed, 0 insertions, 0 deletions