[Gc] Re: Effective heap utilization

Boehm, Hans hans.boehm at hp.com
Fri Oct 12 16:32:25 PDT 2007

> From:  Ludovic Courtès
> Hi,
> "Bruce Hoult" <bruce at hoult.org> writes:
> > The simplest idea is to do a GC_dump() and look at the 
> number of mark 
> > bits set in each heap block compared to the possible number 
> of objects 
> > in that block (the blocksize divided by the size of objects in that 
> > block).
> Good idea.  I used the attached Scheme script to parse the 
> line produced by `GC_dump ()' (or `GC_DUMP_REGULARLY') 
> showing the blocks in use.
> With a libgc-based Guile running a small program creating 
> lots of garbage, I get a total-to-alive heap ratio of 1.03, 
> which seems pretty good (I believe there were no 
> uncollectable objects).
This seems to good to be true.

gc7 with GC_PRINT_STATS set will print totals for reachable memory.

GC_get_free_bytes() currently  only includes bytes in completely empty pages.


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