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Re: GUILE GC -- Write barrier for vectors
From: |
Han-Wen Nienhuys |
Subject: |
Re: GUILE GC -- Write barrier for vectors |
Date: |
Mon, 15 Jul 2002 20:22:19 +0200 |
address@hidden writes:
> > Also, smobs and maybe some other types (which ones? structs?), are
> > always assumed to have been changed, since they are outside of GC's
> > control. It would probably be best to allocate them from a different
> > pool so that they won't poison the normal generations, but that would
> > require a slight extension of the GUILE API.
>
> Do you have a suggestion for such an extension?
SCM scm_changing_cell()
SCM scm_changing_vector()
They would be allocated from a separate memory pool. Also if we
redefine the GC engine to use a different function internally
(i.e. scm_gc_internal_mark), then we can distinguish between data
cells that may be moved (only pointed to from within the heap), and
other cells (marked by scm_gc_mark: conservatively marked entries,
pointed to from smobs, etc.).
The copiable cells could be subjected to copying GC, although it would
require another scan of the entire heap.
>I think, summarizing all thoughts in workbook will be quite helpful.
I much prefer comments in the source code. If you're serious about
hacking that's the first place where you go looking anyways.
> > * Direct write access to a vector must be done through the macro
> > SCM_WRITABLE_VELTS.
>
> Hmmm? Where should this be necessary? Do you want to modify the vector
> cell itself, or are you using this for "speed ups"? In the "speed-up"
> case: wouldn't SCM_VECTOR_SET do as well, given that the compiler can
> extract constant expressions from within loops?
In some cases no (GC manipulations of weak vectors), and in some cases
yes, but it would introduce lots of redtape: long lists of
SCM_VECTOR_SET calls. I'll review the cases once more.
> > * Will this patch be integrated into CVS? The FSF already has
> > disclaimers for me.
>
> I have not looked into the patch yet, but I think that the SCM_VECTOR_SET
> patch as you describe it is probably the right thing to do. I am not sure
> about the need for SCM_WRITABLE_VELTS, but I think we can discuss this
> one. In any case, it would be great if you could contact Michael Livshin.
I assume he is still on the list, reading all my musings? Also I
noticed that Greg Harvey did a lot of work on gengc, but apparently
that didn't work very well?
--
Han-Wen Nienhuys | address@hidden | http://www.cs.uu.nl/~hanwen/
- GUILE GC -- Write barrier for vectors, hanwen, 2002/07/14
- Re: GUILE GC -- Write barrier for vectors, Miroslav Silovic, 2002/07/15
- Re: GUILE GC -- Write barrier for vectors, Dirk Herrmann, 2002/07/15
- Re: GUILE GC -- Write barrier for vectors,
Han-Wen Nienhuys <=
- Re: GUILE GC -- Write barrier for vectors, Dirk Herrmann, 2002/07/15
- Re: GUILE GC -- Write barrier for vectors, Han-Wen, 2002/07/15
- Re: GUILE GC -- Write barrier for vectors, Han-Wen Nienhuys, 2002/07/16
- Re: GUILE GC -- Write barrier for vectors, Dirk Herrmann, 2002/07/16
- Re: GUILE GC -- Write barrier for vectors, Han-Wen, 2002/07/16
- Re: GUILE GC -- Write barrier for vectors, Han-Wen, 2002/07/17
- Re: GUILE GC -- Write barrier for vectors, Dirk Herrmann, 2002/07/19