sampling_counter = “NO_EVENT”
If you don't change this setting, then the samples you have marked will be included with whatever sampling results HP Caliper is set to generate.
You can instead run HP Caliper, specifying
5.Run your application under HP Caliper using that modified measurement configuration file: $ caliper my_pmu_trace myprogram
Figure 31 (page 162) shows part of the resulting report.
Figure 31 Example of PMU Trace Report
PMU Trace Buffer 1, Kernel Thread Id 2218765, Samples 1 - 170 [IIR:IA64_INST_RETIRED, NR: NOPS_RETIRED, CC: CPU_CYCLES]
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Sample | IIR | NR | CC | Bundle Address | Sample |
Number | Count | Count | Count (module:function) | Origin | |
| 1 | 1996102 | 357759 | 2030895 | 0x4001230 | TRG(0x1) |
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| 2 | 73 | 10 | 241 | 0x4001300 | TRG(0x2) |
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| 3 | 4 | 2 | 22 | 0x4001230 | TRG(0x1) |
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| (divmod::main) |
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| 4 | 73 | 10 | 103 | 0x4001300 | TRG(0x2) |
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[... | ] |
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The report shows that 1.9 M instructions retired before HP Caliper took the first sample. The first sample, indicated by TRG(0x1) in the Sample Origin column, was “TRiGgered” by a break instruction generated by the CALIPER_PMU_TAKE_SAMPLE_1() macro.
The second sample was triggered when the processor executed the
CALIPER_PMU_TAKE_SAMPLE_2() macro. Between those two statements, 73 instructions retired, among which were 10 nop instructions, taking 241 cycles.
The third and fourth samples show the same sequence. The report shows that on the second execution the same instructions were executed, but only took 103 cycles. The code executed between the end and the beginning of that particular loop body took about 22 cycles.
Precautions When Using Triggered Samples
Keep these points in mind:
•Generating a large number of triggered samples might result in HP Caliper losing samples. A rule of thumb to avoid losing samples is to limit either of these:
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Total number of such samples to be on the order of hundreds
Rate of sampling to an order of hundreds or thousands of samples per second
•Remove the trigger macros in
The macros CALIPER_PMU_TAKE_SAMPLE_n() expand to generate inline assembly instructions, specifically _Asm_break.
162 HP Caliper Features Specific to 