Re: status: separation of expansion/optimization/memoization/execution

[Han-Wen <hanwen@cs.uu.nl>]

rlb@defaultvalue.org writes:
> 
> BTW has anyone else played with valgrind
> http://developer.kde.org/~sewardj/docs/manual.html?  I'm planning to
> play with it, but so far have only had a chance to see that it doesn't
> like some of our ptr manipulations.  I also wonder if cachegrind might
> be able to tell us anything useful...

Yes, I tried running it on lilypond (which is linked to GUILE). I got
a ton of warnings that was not able to suppress (it seems that the
suppressions don't work for valgrind internal functions, like
strncmp).  Running valgrind for checking is probably pointless for
GUILE, as GUILE manages its own memory; the stack scanning GC also
generates lots of spurious warnings.

I did run it through the CPU cache simulator, which indicated that
gc_mark, gc_sweep and scm_ceval are causing a lot of cache misses.  I
hope to improve the GC part when I can compile guile with GCC 3.1 ;
GCC 3.1 supports prefetch instructions, so cache misses can be
decreased by doing stuff like

	  mark_cons:
	      prefetch (cdr)
	      scm_gc_mark (car)
	      ptr = cdr;
	      goto mark_again;


probably there are some techniques to boost cache rates for eval() as
well.



This is with the java-tree GC benchmark:

--------------------------------------------------------------------------------
I1 cache:         16384 B, 32 B, 4-way associative
D1 cache:         16384 B, 32 B, 4-way associative
L2 cache:         524288 B, 32 B, 4-way associative
Command:          ./libguile/.libs/lt-guile -s /tmp/graphs.sch
Events recorded:  Ir I1mr I2mr Dr D1mr D2mr Dw D1mw D2mw
Events shown:     Ir I1mr I2mr Dr D1mr D2mr Dw D1mw D2mw
Event sort order: Ir I1mr I2mr Dr D1mr D2mr Dw D1mw D2mw
Thresholds:       99 0 0 0 0 0 0 0 0
Include dirs:     
User annotated:   
Auto-annotation:  off

--------------------------------------------------------------------------------
         Ir    I1mr   I2mr          Dr      D1mr    D2mr         Dw    D1mw   D2mw 
--------------------------------------------------------------------------------
566,304,440 177,926 22,634 214,093,739 5,330,222 439,850 60,193,298 122,340 31,098  PROGRAM TOTALS

--------------------------------------------------------------------------------
         Ir   I1mr  I2mr         Dr      D1mr    D2mr         Dw   D1mw   D2mw  file:function
--------------------------------------------------------------------------------
188,450,666 28,572 4,577 69,348,246 1,248,161   6,579 18,620,442 22,047     84  eval.c:scm_ceval
 94,460,034  1,574   368 31,701,931 1,627,987 249,416  7,924,122 14,992  1,579  gc-mark.c:scm_gc_mark_dependencies
 90,846,605  7,899   114 38,685,160   620,624 134,205  5,581,738    746      8  gc-card.c:scm_sweep_card
 36,806,561    479    76 12,092,342    63,732      79  1,526,389      0      0  eval.c:scm_ilookup
 36,027,996     92    11 11,734,622   487,301   2,201  5,880,036 14,057  1,682  gc-mark.c:scm_gc_mark
 12,369,948    642   642  5,936,102   422,488   9,297  1,083,306      0      0  weaks.c:scm_mark_weak_vector_spines
 11,620,162    652   652  4,374,134   353,606   1,097  1,193,150     47      0  weaks.c:scm_scan_weak_vectors
 11,124,410    873    37  5,781,750   106,113      38  2,669,915      7      0  ../libguile/inline.h:scm_acons
  7,826,240  6,519   337  2,201,130    67,895     173    733,710      0      0  vectors.c:scm_vector_ref
  7,241,746    448     5  3,897,614    67,863      27  1,671,236     20      0  ../libguile/inline.h:scm_cons
  7,217,944    902   232  1,740,251     4,410       4  1,332,234  3,415     10  eval.c:scm_eval_args
  6,957,761 16,749 1,561  6,956,140    54,050   2,073        702      6      6  ???:???


-- 

Han-Wen Nienhuys   |   hanwen@cs.uu.nl   |   http://www.cs.uu.nl/~hanwen 

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