Re: [Help-smalltalk] Read-only oldspace

[Paolo Bonzini]

On 05/12/2011 05:24 PM, Holger Hans Peter Freyther wrote:
> How many read-only objects do we have in a bootstrapped image? In a typical
> iliad application? Does it make sense to optimize for it? or will RO handling
> just become more easy and this is a cleanup?

I think the point is to optimize _non_ read-only objects at the cost of 
making tenuring read-only objects a bit more expensive (you will have to 
unprotect the page, allocate, copy, protect the page).  We also win 
read-only access to fixed instance variables, which GNU Smalltalk 
doesn't have (only indexed instance variables are protected).

BTW, for the same reason I think that moving objects to read-only space 
directly when you make them read-only (like you did for fixedspace) is a 
good idea.  Anyway, read-only objects are mostly literals so they are 
long-living.  Gwen, can you reorganize the patch along these lines?

The patch making readonly space, well, readonly should be a separate 
one.  For unprotection/protection around allocation you can add hooks to 
alloc.c heaps, like we have after_allocating: that would be 
before_freeing, after_freeing, before_allocating.

Paolo