It might happen that an event can overflow without
the proper overflow flag set. Check the sign bit in
the raw counter value to solve this problem.
Tested-by: NLin Ming <ming.m.lin@intel.com>
Signed-off-by: NCyrill Gorcunov <gorcunov@openvz.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: fweisbec@gmail.com
Cc: Cyrill Gorcunov <gorcunov@gmail.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
LKML-Reference: <1274083984.6540.15.camel@minggr.sh.intel.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>