tiomap-dev team mailing list archive

[Ricardo Salveti <rsalveti@xxxxxxxxxxxx>]

Here's the kernel with CPU_IDLE disabled:
http://people.linaro.org/~rsalveti/linux-image-3.1.0-1402-linaro-lt-
omap_3.1.0-1402.5_armel.deb

But I was also able to get some fast timings with it sometimes:
 CLOCK_REALTIME tsdiff=166351318.000000 ns (1322121994/667296966 -> 1322121994/500945648
 gettimeofday tvdiff=166351.000000 us (1322121994/667296 -> 1322121994/500945
result=0.225014
 CLOCK_REALTIME tsdiff=72937012.000000 ns (1322121994/744903167 -> 1322121994/671966155
 gettimeofday tvdiff=72937.000000 us (1322121994/744903 -> 1322121994/671966
result=0.225014
 CLOCK_REALTIME tsdiff=169189457.000000 ns (1322121995/11504731 -> 1322121994/842315274
 gettimeofday tvdiff=169189.000000 us (1322121995/11504 -> 1322121994/842315
result=0.225014

But please check and see if you're able to reproduce it at your
enviroment.

-- 
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Developers, which is subscribed to linaro-landing-team-ti.
https://bugs.launchpad.net/bugs/873453

Title:
  odd timing behaviour on panda

Status in Linaro Texas Instruments Landing Team:
  New
Status in Linaro Ubuntu Evaluation Builds:
  New

Bug description:
  I've got a set of benchmarks that use clock_gettime like:

      clock_gettime(CLOCK_REALTIME, &tbefore);

      for(l=0;l<numloops;l++) {
         dostuff
      }

      clock_gettime(CLOCK_REALTIME, &tafter);

      nsdiff=(double)(tafter.tv_nsec - tbefore.tv_nsec);
      nsdiff+=1000000000.0 *(tafter.tv_sec - tbefore.tv_sec);

  
  and I've just reinstalled our local panda to using Linaro 11.09 (kernel 3.0.0-1404-linaro-lt-omap)
  and it's starting to get weird timing artifacts.

  For example:

  smarter_strlen_ldrd: ,102400, loops of ,62, bytes=6.054688 MB, transferred in ,3936768.000000 ns, giving, 1537.984331 MB/s
  smarter_strlen_ldrd: ,102400, loops of ,32, bytes=3.125000 MB, transferred in ,0.000000 ns, giving, inf MB/s
  smarter_strlen_ldrd: ,102400, loops of ,16, bytes=1.562500 MB, transferred in ,4180909.000000 ns, giving, 373.722557 MB/s

  Now there is no way that loop took 0.000000 ns!  Running the same
  binary on an older installation runs fine.

  Dave

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