1. 12 8月, 2009 10 次提交
  2. 11 8月, 2009 10 次提交
  3. 10 8月, 2009 19 次提交
  4. 09 8月, 2009 1 次提交
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      perf tools: callchain: Fix bad rounding of minimum rate · c0a8865e
      Frederic Weisbecker 提交于
      Sometimes we get callchain branches that have a rate under the
      limit given by the user.
      
      Say you launched:
      
       perf record -f -g -a ./hackbench 10
       perf report -g fractal,10.0
      
      And you got:
      
      2.33%       hackbench  [kernel]                  [k] _spin_lock_irqsave
                      |
                      |--78.57%-- remove_wait_queue
                      |          poll_freewait
                      |          do_sys_poll
                      |          sys_poll
                      |          sysenter_dispatch
                      |          0xf7ffa430
                      |          0x1ffadea3c
                      |
                      |--7.14%-- __up_read
                      |          up_read
                      |          do_page_fault
                      |          page_fault
                      |          0xf7ffa430
                      |          0xa0df710000000a
                      ...
      
      It is abnormal to get a 7.14% branch whereas we passed a 10%
      filter.
      
      The problem is that we round down the minimum threshold. This
      happens mostly when we have very low number of events. If the
      total amount of your branch is 4 and you have a subranch of 3
      events, filtering to 90% will be computed like follows:
      
        limit = 4 * 0.9;
      
      The result is about 3.6, but the cast to integer will round
      down to 3. It means that our filter is actually of 75%
      
      We must then explicitly round up the minimum threshold.
      Reported-by: NIngo Molnar <mingo@elte.hu>
      Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
      Cc: acme@redhat.com
      Cc: peterz@infradead.org
      Cc: efault@gmx.de
      LKML-Reference: <20090809024235.GA10146@nowhere>
      Signed-off-by: NIngo Molnar <mingo@elte.hu>
      c0a8865e