Hi folks
recently I did a personal research. I built three different kernel image
(based on 2.6.17-mm6). Each is built using HZ=100, HZ=250 and HZ=1000.
I enabled the full preemption and BKL preemption:
CONFIG_PREEMPT=y
CONFIG_PREEMPT_BKL=y
Booting those kernels, I ran simple tests. One was a simple loop
calculating division between two random long ints, the other one was
playing a MP3 file using mpg123 version 0.59r. The results were:
$ time loop
------------------------------------------------------------------------
HZ=100 HZ=250 HZ=1000
Real 319.326 317.786 319.072
User 319.33 317.801 319.094
System 0 0.001 0
------------------------------------------------------------------------
Table 1. Loop test result (time in seconds)
$ time mpg123 <mp3 file>
------------------------------------------------------------------------
HZ=100 HZ=250 HZ=1000
Real 270.881 270.89 270.884
User 1.877 1.889 1.895
System 0.067 0.068 0.062
------------------------------------------------------------------------
Specificly for mp3 playback, can I conclude that HZ=100 is still the
best choice to reduce audio latency as much as we can?
And for this kind of test, do I need to generate additional
(background?) load such as by running xruns?
Feedbacks are welcome...
regards,
Mulyadi
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