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Re: Speeding up GC
On Tue, Jun 04, 2002 at 08:52:07AM -0700, David S. Miller wrote:
> From: Marc Espie <espie@quatramaran.ens.fr>
> Date: Tue, 4 Jun 2002 17:08:51 +0200
>
> Actually, I can pinpoint it partly: going down such a path would
> 1/ make gcc very much linux-dependent.
>
> Actually, the dirty bit facility in question was orignally found to be
> present under Solaris. Every UNIX provides the mprotect+SIGSEGV
> feature though.
No.
1/ it may be prohibitively expensive on most OSes that implement it.
2/ Here, documentation of mprotect says:
Not all implementations will guarantee protection on a page basis;
the granularity of protection changes may be as large as an entire re-
gion.
Even the linux documentation says something similar:
POSIX.1b says that mprotect can be used only on regions of memory
obtained from mmap(2)