Chapter 4 - DSpace at Waseda University

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Chapter 5
Table 5.2 shows the statistic information on occurred latency such as event names and
execution times and consumption time. Execution time shows how many times each event
was called in a period and consumption time shows overall time of each event during a
period in nanosecond. From Table 5.2, it is possible to analyze event (mm_page_alloc,
net_socket_call, and net_socket_sendmsg) has higher number than other events by analyzing
execution times and consumption time.
Table 5.3: Result of Analysis Layer: (a) Execution times when the time latency did not
occur, (b) Execution times when the time latency occurred
Event name (a) Execution times (b) Execution times
kernel_arch_syscall_entry 37 92
kernel_arch_syscall_exit 37 91
net_socket_recvmsg 0 2
net_socket_sendmsg 0 85
net_dev_xmit 0 85
mm_page_alloc 3 359
mm_page_free 3 20
… … …
kernel_softirq_entry 1 6
kernel_softirq_exit 1 6
kernel_timer_itimer_expired 1 1
Table 5.3 also shows the results of the analysis layer. In the table, the case (a) means
execution times when the time latency did not occur, and the causes (b) means execution
times when the time latency occurred by the network stress and I/O stress program. By
comparing the case (a) to the case (b), we can figure out what event cause the time latency. In
the result, the events - net_socket_sendmsg, net_dev_xmit, mm_page_alloc - were executed