[Qemu-devel] How to measure precise system time in qemu?

[Zack Chen]

Hill all,

I'm now testing some benchmarks on qemu.

I am not sure the time measured by "time" command in linux over qemu is precise,

since that qemu is an emulator.

So,  alternatively, I have tried ssh to a native linux machine to get the correct time.

However, ssh provide some overhead, and this overhead varies every time,

the variance is a large amount in my testbenches.

Is there anything else can help me get more precise execution time?

Here are some of my experiment results:

  

Remote(s)       Local(s)        Benchmark

3.86               3.55            automotive/basicmath

0.65               0.45            automotive/bitcount

0.68               0.48            automotive/qsort

0.73               0.40            automotive/susan

4.60               4.39            telecomm/CRC32

2.93               2.72            telecomm/FFT

3.20               2.96            telecomm/adpcm

2.03               1.84            telecomm/gsm

0.20               0.01            office/stringsearch

3.34               3.11            office/ispell

5.88               5.66            office/rsynth

1.37               0.96            office/ghostscript

0.51               0.30            network/dijkstra

1.27               0.85            network/patricia

0.47               0.17            consumer/jpeg

1.11               0.84            consumer/typeset

0.69               0.45            consumer/tiff2bw

1.32               1.10            consumer/tiff2rgba

1.12               0.93            consumer/tiffdither

1.15               0.95            consumer/tiffmedian

0.19               0.00            consumer/lame

0.19               0.00            consumer/mad

Thanks.

Zack