[ltt-dev] General Questions

[Kevin Harms]

  I've made progress with processing the trace output, but I'm not sure I'm seeing what I expect.

  I ran a trace of my test program which produced the following output:

0.014005
0.013193
0.913196
0.012794
0.013194
0.013196
0.013195
0.012796
0.026788
0.912795
0.013195
0.012794
0.013196
0.013195
0.013195
0.012795
0.913194
0.013196
0.013195
0.013196

  These are timings of fsync(). You can see normally the fsync time is on the order of 0.01 seconds but sometimes there's a 0.9 second one. This occurs on different hardware and file systems, so it would seem to be something with my test program or linux. Looking at the trace output. I don't really see this. The fsync calls seemed to be at regular intervals with no obvious ones taking longer than expected. See the screen shot at the link below. Am I looking in the wrong place?

http://www-unix.mcs.anl.gov/~harms/lttv-capture.png

thanks,
kevin