[Libguestfs] Effect of memsize

[Richard W.M. Jones]

Marek, here are my results from a simple and small read-only test.

libguestfs 1.11.13

The test is to run the command below 3 times in a row for each memory
setting, and take the elapsed time of only the final run.

LIBGUESTFS_MEMSIZE=nnnn \
guestfish --ro -i -d F14x64 \
  inspect-list-applications /dev/vg_f13x64/lv_root > /dev/null

The test machine is my laptop which has 4GB of RAM and is mostly idle.

   257 0m14.908s   [note 1]
   500 0m14.773s   [note 2]
  1024 0m14.886s
  2048 0m14.855s
  4096 0m14.861s
  8192 0m14.908s   [note 3]
 32768 0m17.580s   [note 3]

Apart from the 32GB guest, those times are well within the margin of
variability.  Essentially they all take the same amount of time except
for the last one.

Rich.

---

Notes:

[1] Minimum permitted size.

[2] Default setting.

[3] I had to enable Linux memory overcommit for this test.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
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