* scm_must_realloc mallocated count in 1.6
@ 2006-03-19 22:46 Kevin Ryde
2006-03-25 22:56 ` Marius Vollmer
0 siblings, 1 reply; 2+ messages in thread
From: Kevin Ryde @ 2006-03-19 22:46 UTC (permalink / raw)
There's a bit of a bug in scm_must_realloc and its scm_mallocated
counting in 1.6.
If you tell scm_must_realloc to decrease the size of a block, it
doesn't change scm_mallocated count, so when you later report the new
size in the free, the final scm_mallocated is off by the difference
(ie. bigger than it should be).
This occurs in the core with bignums when scm_i_adjbig trims off
excess digits from the end of a block. It might happen with
applications, though perhaps realloc to decrease isn't too common.
A little loop that shows the problem is
(while #t
(ash 1 256)
(gc)
(pk (assq-ref (gc-stats) 'bytes-malloced)))
The count printed keeps going up.
I'm inclined to remove the short-circuit
if (size <= old_size)
return where;
from scm_must_realloc, ie. if you ask to decrease a block then
actually do it, which is what 1.8 has now.
The alternative would be to leave no realloc() on decrease, but do
adjust scm_mallocated. That would mean scm_mallocated doesn't reflect
the amount of malloc actually in use, which wouldn't be a good thing
for the mtrigger stuff.
_______________________________________________
Guile-devel mailing list
Guile-devel@gnu.org
http://lists.gnu.org/mailman/listinfo/guile-devel
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: scm_must_realloc mallocated count in 1.6
2006-03-19 22:46 scm_must_realloc mallocated count in 1.6 Kevin Ryde
@ 2006-03-25 22:56 ` Marius Vollmer
0 siblings, 0 replies; 2+ messages in thread
From: Marius Vollmer @ 2006-03-25 22:56 UTC (permalink / raw)
Kevin Ryde <user42@zip.com.au> writes:
> I'm inclined to remove the short-circuit
>
> if (size <= old_size)
> return where;
>
> from scm_must_realloc, ie. if you ask to decrease a block then
> actually do it, which is what 1.8 has now.
Sounds good to me.
--
GPG: D5D4E405 - 2F9B BCCC 8527 692A 04E3 331E FAF8 226A D5D4 E405
_______________________________________________
Guile-devel mailing list
Guile-devel@gnu.org
http://lists.gnu.org/mailman/listinfo/guile-devel
^ permalink raw reply [flat|nested] 2+ messages in thread
end of thread, other threads:[~2006-03-25 22:56 UTC | newest]
Thread overview: 2+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2006-03-19 22:46 scm_must_realloc mallocated count in 1.6 Kevin Ryde
2006-03-25 22:56 ` Marius Vollmer
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).