IBM Power7 Optimization And Tuning Manual page 182

9907
34282
As a first step, compare the mix of system calls to the expectation of how the application is
expected to behave. Is the mix aligned with expectations? If not, first confirm that the trace is
collected while the wanted workload runs. If the trace is collected at the correct time and the
mix still differs from expectations, then investigate the application logic. Also, examine the list
of system calls for potential optimizations. For example, if select or poll is used frequently,
consider employing the pollset facility (see "pollset" on page 71).
As a further breakdown, curt provides a report of the system calls run by each thread. An
example report is shown in Example B-5.
Example B-5 system calls run by each thread
Report for Thread Id: 549305 (hex 861b9) Pid: 323930 (hex 4f15a)
Process Name: proc1
--------------------
Total Application Time (ms): 89.010297
Total System Call Time (ms): 160.465531
Total Hypervisor Call Time (ms): 18.303531
Count
======== =========== ======== ======== ======== ================
492
494
12
6
4
Another useful report that is provided by curt is the
summary shows the list of threads that are in an unfinished system call at the end of the
trace. An example report is given in Example B-6.
Example B-6 Threads that are in an unfinished system call at the end of the trace
Pending System Calls Summary
Accumulated
Time (msec)
============ =========================
0.0082 GetMultipleCompletionStatus(549a6a8)
0.0089 _nsleep(2a28d30)
0.0054 _thread_wait(2a28778)
0.0088 GetMultipleCompletionStatus(549a6a8)
3.3981 listio64(516ea40)
0.0130 kpwrite(2a2d588)
For each thread in an unfinished system call, the following items are provided:
The accumulated time in the system call
The name of the system call (followed by the system call address in parentheses)
The process name, followed by the Process ID and Thread ID in parentheses
166
POWER7 and POWER7+ Optimization and Tuning Guide
266.1382 1.23%
167.8132 0.77%
Thread System Call Summary
--------------------------
Total Time Avg Time Min Time Max Time SVC (Address)
(msec) (msec)
157.0663 0.3192
3.3656 0.0068
0.0238 0.0020
0.0060 0.0010
0.0028 0.0007
----------------------------
SVC (Address)
0.0269 0.0143
0.0049 0.0032
(msec) (msec)
0.0032 0.6596 listio64(516ea40)
0.0002 0.0163 GetMultipleCompletionStatus(549a6a8)
0.0017 0.0022 _thread_wait(2a28778)
0.0007 0.0014 thread_unlock(2a28838)
0.0005 0.0008 thread_post(2a288f8)
Pending System Calls Summary
0.5350 kpwrite(2a2d588)
0.0204 _thread_wait(2a28778)
. This
Procname (Pid Tid)
==========================
proc1(323930 532813)
proc2(270398 545277)
proc1(323930 549305)
proc1(323930 561437)
proc1(323930 577917)
proc1(323930 794729)