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Overall Performance Analysis Approach
• Concentrate on business critical application(s)
• Understand thread states○ Blocked (Sleeping) – on what?○ Running – what code?
• Use appropriate tools○ truss, strace○ snoop, tcpdump○ pfiles, lsof○ prstat –Lmn20 1○ DTrace
• Latency Profiles○ I/O○ Network○ Memory○ Functions in application
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Profiling Application Execution
• Useful DTrace one-liner to capture what code is being executed:
# dtrace -n 'profile-301 /arg1/ {@[execname, ustack()] = count()} tick-20s {trunc(@,16); exit(0)}'
dtrace: description 'profile-301 ' matched 2 probes
…
java
libjvm.so`__1cJMarkSweepOIsAliveClosureLdo_object_b6MpnHoopDesc__i_+0x8
libjvm.so`__1cLPSMarkSweepQinvoke_no_policy6Fpii_v_+0x6b4
libjvm.so`__1cLPSMarkSweepGinvoke6Fpii_v_+0xa4
libjvm.so`__1cVVM_ParallelGCSystemGCEdoit6M_v_+0xf8
libjvm.so`__1cMVM_OperationIevaluate6M_v_+0x80
libjvm.so`__1cIVMThreadDrun6M_v_+0x6e0
libjvm.so`__1cG_start6Fpv_0_+0x208
libc.so.1`_lwp_start
209
ns-slapd
libdb.so.2`__memp_stat_hash+0x54
libdb.so.2`__memp_trickle_pp+0x144
libback-ldbm.so`trickle_threadmain+0xb8
libnspr4.so`_pt_root+0xc8
libc.so.1`_lwp_start
368
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Profiling Application Latency
#!/usr/sbin/dtrace -s
/*
* Usage: time-funcs.d -p pid
* time-funcs.d -c 'application args'
*/
pid$target:::entry
{ self->ts[self->depth++] = timestamp; }
pid$target:::return
/self->ts[--self->depth] != 0/
{
@[probefunc ] = quantize(timestamp - self->ts[self->depth]);
self->ts[self->depth] = 0;
}
tick-30s
{ exit(0); }
END
{ trunc(@, 20);}
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Partial Output from D Script
select
value ------------- Distribution ------------- count
33554432 | 0
67108864 |@@@@@@@@@@@@@@@@@@@@@@ 294
134217728 |@@@@@@@@@ 118
268435456 | 0
536870912 |@@@@@@@@@ 116
1073741824 | 0
pthread_cond_timedwait
value ------------- Distribution ------------- count
524288 | 0
1048576 | 1
2097152 | 0
4194304 | 0
8388608 | 1
16777216 | 2
33554432 |@@ 8
67108864 |@@@@@@@ 32
…
