• Kan Liang's avatar
    perf/x86/intel: Disable userspace RDPMC usage for large PEBS · 2c2a9bbe
    Kan Liang authored
    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: default avatarKan Liang <kan.liang@linux.intel.com>
    Signed-off-by: default avatarPeter 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.comSigned-off-by: Ingo Molnar's avatarIngo Molnar <mingo@kernel.org>
    (cherry picked from commit 1af22eba)
    2c2a9bbe
core.c 59.8 KB