]> git.baikalelectronics.ru Git - kernel.git/commit
perf/x86/intel: Disable userspace RDPMC usage for large PEBS
authorKan Liang <kan.liang@linux.intel.com>
Mon, 12 Feb 2018 22:20:35 +0000 (14:20 -0800)
committerIngo Molnar <mingo@kernel.org>
Fri, 9 Mar 2018 07:22:23 +0000 (08:22 +0100)
commitce2e78c3e280cb9d27113877bc4f9528e789bb43
tree84d02e80753be291c9dbe2b753574ca7521b67d5
parenta9168a7af5066f2c8edfaeee85ccd541fa9c0597
perf/x86/intel: Disable userspace RDPMC usage for large PEBS

Userspace RDPMC cannot possibly work for large PEBS, which was introduced in:

  b8241d20699e ("perf/x86/intel: Implement batched PEBS interrupt handling (large PEBS interrupt threshold)")

When the PEBS interrupt threshold is larger than one, there is no way
to get exact auto-reload times and value for userspace RDPMC.  Disable
the userspace RDPMC usage when large PEBS is enabled.

The only exception is when the PEBS interrupt threshold is 1, in which
case user-space RDPMC works well even with auto-reload events.

Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.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: acme@kernel.org
Fixes: b8241d20699e ("perf/x86/intel: Implement batched PEBS interrupt handling (large PEBS interrupt threshold)")
Link: http://lkml.kernel.org/r/1518474035-21006-6-git-send-email-kan.liang@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
arch/x86/events/core.c