Monthly Archives: August 2009

I’ve been working on rewriting Sheeple these past couple of days. The new version will be a major bottom-up redesign, mainly to the lowlevel stuff. The early results without too-crazy optimization are already showing up, and it’s quite nice.

These numbers are on Clozure CL x86  Linux:

SHEEPLE> (time (loop repeat 100000 do (allocate-std-sheep)))
(LOOP REPEAT 100000 DO (ALLOCATE-STD-SHEEP)) took 119 milliseconds (0.119 seconds) to run
                    with 2 available CPU cores.
During that period, 106 milliseconds (0.106 seconds) were spent in user mode
                    3 milliseconds (0.003 seconds) were spent in system mode
50 milliseconds (0.050 seconds) was spent in GC.
 4,000,000 bytes of memory allocated.
 19 minor page faults, 0 major page faults, 0 swaps.

And a single sheep object:

SHEEPLE> (time (allocate-std-sheep))
(ALLOCATE-STD-SHEEP) took 0 milliseconds (0.000 seconds) to run
                    with 2 available CPU cores.
During that period, 0 milliseconds (0.000 seconds) were spent in user mode
                    0 milliseconds (0.000 seconds) were spent in system mode
 40 bytes of memory allocated.

Now, that’s still a bit heavy compared to CLOS (which only allocates 24 bytes for a raw instance), and to be honest, I’m not aiming at beating CLOS. It’s like a class-based system trying to beat out structs. On the other hand, it’s actually pretty nice to shrink everything down to more usable levels.
The current Sheeple release, for example, the one built on top of CLOS, is quite a monster:

SHEEPLE> (time (loop repeat 100000 do (allocate-sheep)))
(LOOP REPEAT 100000 DO (ALLOCATE-SHEEP)) took 11,273 milliseconds (11.273 seconds) to run
                    with 2 available CPU cores.
During that period, 10,716 milliseconds (10.716 seconds) were spent in user mode
                    204 milliseconds (0.204 seconds) were spent in system mode
3,249 milliseconds (3.249 seconds) was spent in GC.
 244,000,000 bytes of memory allocated.
 9,419 minor page faults, 0 major page faults, 0 swaps.

So yeah, this is a huge improvement.

Keep in mind that all of these numbers don’t yet take into account what the full cost of a raw (clone) will be, although it won’t be much higher than what it is right now (I believe it will only be two extra words, because an item will be added to the parents list).

It’s a bit fun to mess around with stuff so carefully at a lower level…