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Hi everyone,</p>
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I have a question about the time measure measurement in ft_trace in Litmus.</p>
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I was wondering how does the ft_trace get the timestamp information, then I found that it used this function:</p>
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#include <asm/feather_trace.h></p>
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#include <asm/timex.h> /* for get_cycles() */</p>
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<span style="font-size:12pt">static inline unsigned long long ft_timestamp(void)</span></p>
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{</p>
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return get_cycles();</p>
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}</p>
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This function will return the cycle of the CPU, I checked all the program in the ft_tool and the sched-trace-tool-master, I thought when you get_cycles of the CPU, should not you divide the current frequency of the CPU to get the time. I did not find the division,
or the current get cycle did give you the time information?</p>
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When I run a small program, I get the output here, and I also send a picture as an attachment.</p>
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<p>luozheng@luozheng-Ubuntu:~/Documents/Litmus/sched-trace-tools-master$ ./st_show st--6.bin </p>
<p>[ 0] NAME 4420/0 on CPU 6 base_task</p>
<p>[ 0] PARAM 4420/0 on CPU 6 T=(cost:100.00ms, period:500.00ms, phase: 0.00ms), part=0</p>
<p>[ 2914923] SWITCH_FROM 4420/1 on CPU 6 </p>
<p>[ 2914923] SWITCH_TO 4420/1 on CPU 6 </p>
<p>[ 2914923] SWITCH_FROM 4420/1 on CPU 6 </p>
<p>[ 2914923] COMPLETION 4420/1 on CPU 6 </p>
<p>[ 2915423] RELEASE 4420/2 on CPU 6 2915923.27ms</p>
<p>[ 2915423] SWITCH_TO 4420/2 on CPU 6 </p>
<p>[ 2915774] SWITCH_FROM 4420/2 on CPU 6 </p>
<p>[ 2915774] COMPLETION 4420/2 on CPU 6 </p>
<p>[ 2915923] RELEASE 4420/3 on CPU 6 2916423.27ms</p>
<p>[ 2915923] SWITCH_TO 4420/3 on CPU 6 </p>
<p>[ 2916274] SWITCH_FROM 4420/3 on CPU 6 </p>
<p>[ 2916274] COMPLETION 4420/3 on CPU 6 </p>
<p>[ 2916423] RELEASE 4420/4 on CPU 6 2916923.27ms</p>
<p>[ 2916423] SWITCH_TO 4420/4 on CPU 6 </p>
<p>[ 2916774] COMPLETION 4420/4 on CPU 6 </p>
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I get a little confused here. Is number in the [] should be the cycles of the CPU? The number like <span style="font-size: 12pt;">2915923.27ms is the actual time? Or how do we interpret this? I think I need some help here. Thank you very much.</span></p>
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<div>Zheng Luo<br>
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