Re: Better memory statistics, take 2

[Matt Austern <austern at apple dot com>]

On Sep 2, 2004, at 9:23 AM, Zack Weinberg wrote:

> Jan Hubicka <hubicka@ucw.cz> writes:
>
> > Hi,
> > here is updated version of patch I sent while reducing memory for GCC
> > 3.4, it is quite usefull now again...
> >
> > Hi, this patch improves the per-line statistics by tracking down
> > each allocated entity to figure out whether it will be freed,
> > garbage collected or leaked.  To rule out ggc_freed values is pretty
> > important as these are much cheaper,
> ...
>
> Please do timing tests before submitting any changes.  In my
> experience ggc_free is *not* cheaper, it is by itself such an
> expensive operation that we don't actually gain anything over
> letting the garbage collector do its job.

What this does mean is that if we know a data structure will be 
temporary, we shouldn't use ggc_free or ggc_anything.

			--Matt