Re: [Axiom-developer] Mark Botch

[Camm Maguire]

:-)

(wondering what neat pseudonym still left for me to claim...)

Just a quick note to state that a significant gbc leak was plugged
some months ago due to a report by an acl2 user, which involved the
interaction of contiguous page garbage collection and SGC toggling.
Object modules are loaded into contiguous pages.  Wondering if there
is any significant size difference with --enable-static.  Wondering
also if axiom uses sgc.  Only time I've ever seen a mark botch is when
heap memory somehow gets allocated past heap_end and into either the
hole or the relocatable block section.  It may be useful to recall
that GCL memory is organized into non-relocatable pages of various
types below heap_end, then a hole of size holesize, then a relocatable
block section up to core_end, which can be extended up to maxpages.

I must say I haven't seen anything like this in ages -- the gbc has
been extremely stable since I've worked on gcl save for the one leak
mentioned above.  Of course I'd be most appreciative of any uncovering
of a bug in this area.

Take care,


Tim Daly  <address@hidden> writes:

> Bill,
> 
> Guffaw. I owe you. One of my old areas of expertise is memory
> management and I spent quite a while talking to Bill Schelter
> about akcl garbage collection. One of the phases of garbage
> collection is called the "mark" phase where you mark all of
> the "live" objects (then you collect the dead objects and
> reclaim memory). The error message is "mark botch". I got it
> so often that I adopted the pseudonym of "Mark Botch" when
> writing to Bill.
> 
> Clearly the garbage collector is unhappy. I'll look at the
> code and see if I can figure out why.
> 
> Tim "Mark Botch" Daly
> 
> 
> 
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> 
> 
> 

-- 
Camm Maguire                                            address@hidden
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