Subject: Re: New ld.elf_so from FreeBSD
To: Charles Hannum <firstname.lastname@example.org>
From: Jason R Thorpe <email@example.com>
Date: 09/05/2002 12:44:17
On Thu, Sep 05, 2002 at 02:24:36AM +0000, Charles Hannum wrote:
> * C++ code (and thus GNOME, KDE, mozilla, etc.) starts up much faster.
junyoung has a patch that addresses this problem.
> * The Alpha platform attains reasonable performance, where right now
> things like the XF86 4 server are basically unusable.
What you've neglected to tell the list is that you have already patched
our ld.elf_so to fix this problem, but have not yet checked it in to the
> * The occasional `undefined PLT symbol' problems (on Alpha) are gone.
Again, you neglected to tell the list that you debugged, and fixed, this
already in our ld.elf_so.
> * Multi-threading support (i.e. r/w locking for dl*() calls) is added.
I think there are some problems with this.
1. We've been talking a lot about performance of the dynamic
linker lately. The r/w locking is totally unnecessary for
non-threaded applications. Making non-threaded applications
pay the penalty of using them seems to go against the spirit
of improving performance.
2. Since not all platforms have the required atomic primitives
to support the r/w locking, the expense incurred by using them
for non-threaded apps might, in fact, be substantial (e.g.
unnecessarily making all processes on that platform use RAS,
I agree that we need r/w locking support in our rtld, but I think the
problem is big enough that we need to think about it a while longer before
simply adopting a solution from some other system which doens't run on
as many platforms as we run on.
-- Jason R. Thorpe <firstname.lastname@example.org>