gprof performance analysis

Each sample counts as 0.01 seconds.
  %   cumulative   self              self     total           
 time   seconds   seconds    calls   s/call   s/call  name    
 49.99     39.28    39.28                             writev
  5.42     43.54     4.26                             epoll_ctl
  3.16     46.02     2.48                             read
  2.41     47.91     1.89   265797     0.00     0.00  SrsProtocol::send_message(ISrsMessage*)
  1.93     49.43     1.52                             __gnu_mcount_nc
  1.82     50.86     1.43                             epoll_wait
  1.67     52.17     1.31       33     0.04     0.42  SrsRtmpConn::playing(SrsSource*)
  1.49     53.34     1.17                             heap_insert
  1.37     54.42     1.08                             heap_delete
  1.31     55.45     1.03                             _st_epoll_dispatch
  0.97     56.21     0.76                             st_writev
  0.84     56.87     0.66                             _st_epoll_pollset_del
  0.71     57.43     0.56   295144     0.00     0.00  SrsProtocol::recv_interlaced_message