[gnuastro-devel] [task #14100] Script to configure and build in tmpfs (RAM)

[Mohammad Akhlaghi]

Follow-up Comment #4, task #14100 (project gnuastro):

Great test, thank you! I also tried it out. But I didn't do the bootstrapping
because this script is only concerned with configure and make. Both were run
after a 'make distclean'.


$ time (./configure &&make -j8)
...
real    0m31.752s
user    0m38.003s
sys     0m3.927s

-------------

$ time (./parallel-build-in-tmpfs)
...
real    0m29.958s
user    0m36.473s
sys     0m3.487s


For me it was just slightly (<2 sec) faster! I then thought it might be
because of the source file reading speed bottle-neck. Since the source wasn't
in the RAM. So I unpacked a 'make dist' tarball in the /dev/shm and ran
configure and make there. The result wasn't any different (within errors) than
the './parallel-build-in-tmpfs' result above:


real    0m30.685s
user    0m37.317s
sys     0m3.510s


I then checked the memory usage before and after the processes involving
/dev/shm (to make sure that tmpfs was actually in the RAM, not SWAP) and I saw
that indeed the files are in the RAM. So I am also confused!

The main thing I was concerned about when coming up with this script was the
burden of a large number of read/writes on the SSD drive. I hadn't actually
objectively tested the running time like the test above. I guess this shows
how important prejudice is ;-)!

I am curious if you are also using an SSD or HDD? Since your running time is
so similar to mine, I guess you are also using an SSD, right? Probably on a
HDD the difference might be more. I can't test on a HDD now.

At least I feel it is good that the writings of small files are done in the
RAM not on the SSD. But I am still confused how the running time difference is
so small.

    _______________________________________________________

Reply to this item at:

  <http://savannah.gnu.org/task/?14100>

_______________________________________________
  Message sent via/by Savannah
  http://savannah.gnu.org/