• Alexander Shishkin's avatar
    perf tools: Handle partial AUX records and print a warning · 05a1f47e
    Alexander Shishkin authored
    This patch decodes the 'partial' flag in AUX records and prints
    a warning to the user, so that they don't have to guess why their
    PT traces contain gaps (or missing altogether):
    
      Warning:
      AUX data had gaps in it 8 times out of 8!
    
      Are you running a KVM guest in the background?
    
    Trying to be even more helpful, we will detect if the user's kvm driver sets up
    exclusive VMX root mode for the entire lifespan of the kvm process:
    
      Reloading kvm_intel module with vmm_exclusive=0
      will reduce the gaps to only guest's timeslices.
    
    Note however, that you'll still have gaps in cpu-wide traces even with
    vmm_exclusive=0, but the number of gaps will be below 100% (as opposed to the
    above example).
    
    Currently this is the only reason for partial records.
    Signed-off-by: default avatarAlexander Shishkin <alexander.shishkin@linux.intel.com>
    Cc: Adrian Hunter <adrian.hunter@intel.com>
    Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
    Cc: Stephane Eranian <eranian@google.com>
    Cc: Vince Weaver <vince@deater.net>
    Link: http://lkml.kernel.org/r/8760j941ig.fsf@ashishki-desk.ger.corp.intel.comSigned-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
    05a1f47e
session.c 58.8 KB