Performance issue

[Philipp Klaus Krause <pkk@spth.de>]

There's something wrong when running the sdcc regression tests on Hurd
inside kvm (checked out sdcc from svn, built it and then tried to run
the tests in support/regression): They are supposed to take their cpu
time in the compiler or simulator (ucsim). When I run them on the host
they are cpu bound. However on Hurd, they eat nearly no CPU time
according to top, the host doesn't show significant cpu usage during
that time either. The disc isn't particularly active (writeback cache
seemed to help), there's not even a lot of e2fs activity.
Nevertheless running the tests is really slow (I guess between 100 and
1000 times as long as on the host). Could it be that ucsim is programmed
in a way that makes it very it very slow when run on an os inside a vm?
I have no idea if this is a vm, hurd or ucsim issue.

Philipp

When running the regression test using make -j 3 test-ucgbz80, there are
three running ucsim processes:

top - 16:33:47 up 15456 days, 16:33,  0 users,  load average: 3.55,
3.12, 3.06
Tasks:  66 total,   0 running,  64 sleeping,   0 stopped,   0 zombie
Cpu(s):  1.6% us,  0.0% sy,  0.0% ni, 98.4% id,  0.0% wa,  0.0% hi,  0.0% si
Mem:    524276k total,   225944k used,   298332k free,        0k buffers
Swap:   177148k total,        0k used,   177148k free,        0k cached

  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND




    3 root      20   0  479m  43m    0 S  0.5  8.4   7:32.22 ext2fs




    2 root       6 -14  674m  19m    0 D  0.0  3.7   0:02.26
root=device:hd0



  508 philipp   20   0  148m 6316    0 S  0.0  1.2   0:00.37 -bash




  413 philipp   20   0  148m 6272    0 S  0.0  1.2   0:00.37 -bash




  507 root      20   0  130m 4448    0 S  0.0  0.8   0:05.36 /hurd/term




25100 philipp   20   0  135m 4244    0 S  0.0  0.8   0:02.85 make




  393 root      20   0  147m 3448    0 S  0.0  0.7   0:00.24 -bash




  405 root      20   0 14444 3440    0 H  0.0  0.7   0:00.06
/usr/sbin/sshd



  407 root      20   0 14444 3408    0 H  0.0  0.7   0:00.07
/usr/sbin/sshd



  570 philipp   20   0  147m 3264    0 S  0.0  0.6   0:00.01
../../sim/ucsim



  563 philipp   20   0  147m 3216    0 S  0.0  0.6   0:00.01
../../sim/ucsim



  555 philipp   20   0  147m 3204    0 S  0.0  0.6   0:00.02
../../sim/ucsim



  357 root      20   0  131m 2076    0 S  0.2  0.4   0:06.29
/hurd/pfinet



  411 philipp   20   0 14456 1836    0 S  0.0  0.4   0:00.20
/usr/sbin/sshd



  389 root      20   0  133m 1808    0 S  0.0  0.3   0:00.02
/hurd/console



  506 philipp   20   0 14456 1792    0 S  0.0  0.3   0:00.25 /usr/sbin/sshd