[PATCH] provide means to access the zone from the corresponding chunk

[Daniel Berlin]

On May 8, 2004, at 2:57 AM, Paolo polimi wrote:

Daniel Berlin wrote:

On May 7, 2004, at 9:59 AM, Paolo Bonzini wrote:
This patch enables the zone collector to recover the page_entry and
alloc_zone structures from the address of an arbitrary ggc_alloc-ed 
pointer.  Unfortunately, while very useful, this is quite invasive.
Why do we need to do this?
What exactly useful property does being able to get the page entry 
have?
It allows to recover the zone from the chunk, without *any* kind of 
overhead.  For example, it allows to track inter-zone pointers or 
chunks that live in the garbage_zone.
Sorry if i seemed abrupt. It's finals time, and I was incredibly 
curious what you were going to use this for.
If that is your goal, it may indeed be worth it.
Tracking inter-zone pointers is necessary to be able to mark one zone 
at a time (without marking other zones).
However, there are other things necessary to do this that I was working 
on first (you need to be able to mark by typecode, at least for most 
things. This ends up being more invasive than we'd like.)
I agree it may not be worth spending four bytes per chunk, but at zero 
cost...


Paolo