Frederic Weisbecker 2f01190aa6 perf top: Wait for a minimal set of events before reading first snapshot ... The first snapshot reading often occur before any events have been read in the mapped perfcounter files. Just wait until we have at least one event before starting the snapshot, or the delay before the first set of entries to be displayed may be long in case of low refresh rate. Note: we could also use a semaphore to wait before "print_entries" number of eveents is reached, but again this value is tunable and we can't ensure we will even reach it. Also we could base on a default mimimum set of entries for the first refresh, say 15, but again, the minimal sample is tunable, and we could end up displaying nothing until we have a minimal default set of events, which can take some time in case of high samples filters. Hence this simple solution which partially covers the default case. [ Impact: fix display artifacts in perf top ] Signed-off-by: Frederic Weisbecker <fweisbeec@gmail.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Mike Galbraith <efault@gmx.de> Cc: Paul Mackerras <paulus@samba.org> Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> LKML-Reference: <1244322643-6447-1-git-send-email-fweisbec@gmail.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>		2009-06-07 09:32:44 +02:00
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perf	perf top: Wait for a minimal set of events before reading first snapshot	2009-06-07 09:32:44 +02:00