From: rogerdpack <rogerpack2005@...>
Date: 2008-12-14T13:14:40+09:00
Subject: [ruby-core:20542] Re: New shootout

> And if I remember correctly, tweaking 1.9's GC also benefits from
> tweaking [2].

example of what tweaking the gc can do [Cangiano benchmark]
Ruby 1.9 normal:

real-world/bm_hilbert_matrix.rb,
4.0054624080658,4.09904861450195,4.052255511283875,0.046793103218079,50
real-world/bm_hilbert_matrix.rb,
8.86907505989075,12.8570592403412,10.863067150115967,1.993992090225220,60

ruby 1.9 trunk with GC patch [1]

real-world/bm_hilbert_matrix.rb,
2.87246918678284,2.8920271396637,2.882248163223267,0.009778976440430,50
real-world/bm_hilbert_matrix.rb,
6.63441443443298,6.49161219596863,6.563013315200806,0.071401119232178,60

With GC.disable

real-world/bm_hilbert_matrix.rb,
2.61896514892578,2.60238766670227,2.610676407814026,0.008288741111755,50
real-world/bm_hilbert_matrix.rb,
5.82226586341858,5.81672692298889,5.819496393203735,0.002769470214844,60

So there is still room for improvement [i.e. with something like [0]],
but some benefit is gained with tuning.

Thanks!
-=R

[0] http://www.nabble.com/GC-patch-for-1.9-to-run-in-a-separate-thread-td20082948.html
[1]
Index: gc.c
===================================================================
--- gc.c        (revision 20731)
+++ gc.c        (working copy)
@@ -75,7 +75,7 @@
 #endif /* __GNUC__ */

 #ifndef GC_MALLOC_LIMIT
-#define GC_MALLOC_LIMIT 8000000
+#define GC_MALLOC_LIMIT 80000000
 #endif

 #define nomem_error GET_VM()->special_exceptions[ruby_error_nomemory]
@@ -281,7 +281,7 @@
     int limit;
 };

-#define HEAP_MIN_SLOTS 10000
+#define HEAP_MIN_SLOTS 100000
 #define FREE_MIN  4096

 struct gc_list {