James E Keenan wrote:
Last night bacek was able to devote some attention to this problem. He
pointed to a particular line of code recently merged in from the
gc_massacre branch and asked me to make a manual change:
$ svn diff
Index: src/gc/gc_ms2.c
===================================================================
--- src/gc/gc_ms2.c (revision 49323)
+++ src/gc/gc_ms2.c (working copy)
@@ -623,7 +623,8 @@
/* Collect every 256M allocated. */
/* Hardcode for now. Will be configured via CLI */
- self->gc_threshold = 256 * 1024 * 1024;
+/* self->gc_threshold = 256 * 1024 * 1024; */
+ self->gc_threshold = 64 * 1024 * 1024;
}
interp->gc_sys->gc_private = self;
256M happens to be amount of Physical Memory reported by 'top' for this
machine. Changing the gc_threshold from 256M to 64M did enable 'make
test' to run completely (including t/compilers/opsc/*.t) and PASS in
about 19 minutes. So the value of the gc_threshold does have a
significant impact on whether parrot will run (in any meaningful sense)
on a particular machine.
I decided to extend this experiment by further decreasing the value
assigned to self->gc_threshold by another factor of 4:
Index: src/gc/gc_ms2.c
===================================================================
--- src/gc/gc_ms2.c (revision 49339)
+++ src/gc/gc_ms2.c (working copy)
@@ -623,7 +623,9 @@
/* Collect every 256M allocated. */
/* Hardcode for now. Will be configured via CLI */
- self->gc_threshold = 256 * 1024 * 1024;
+/* self->gc_threshold = 256 * 1024 * 1024; */
+/* self->gc_threshold = 64 * 1024 * 1024; */
+ self->gc_threshold = 16 * 1024 * 1024;
}
interp->gc_sys->gc_private = self;
With this setting, 'make' completed in 11:40 (versus 12:20 with setting
of 64M), the tests in t/compilers/opsc/*.t took 6:05 (versus something
over 7 minutes; I didn't record exact value), and 'make test' as a whole
took 15:28 (versus something in the 19-minute) range. This suggests
that on this low-physical-memory box, I get better performance the
*lower* I set the GC threshold.
Thank you very much.
kid51
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