Greetings,
A user on unix.com posted this query :
> Does anyone know or know how to check if the Apache 2.2 version you can get
> with the Synaptic Package manager in Ubuntu 8.10has been optimized for 486 or
> higher processors?
He then quotes from the documentation on tuning:
> By default, APR uses mutex-based atomics on Linux. If you configure with
> --enable-nonportable-atomics, however, APR generates code that uses a 486
> opcode for fast hardware compare-and-swap. This will result in more efficient
> atomic operations, but the resulting executable will run only on 486 and
> later chips (and not on 386).
Looking into this, I discovered that the APR's configure code will
use generic atomics (as opposed to inline assembly) under all x86
platforms *except* i386 and x86_64 (and unless specifically overridden
on the command line). Here's the thread in the mailing list which
includes the patch and commentary (but not rationale) from
jor...@apache.org in 2004:
http://mail-archives.apache.org/mod_mbox/apr-commits/200401.mbox/<20040106150746.91496.qm...@minotaur.apache.org>
My question is: *why* ?? Why default to generic atomics on i486's and
later, but not x86_64? I think this is a bug in the configure logic,
but I'm not sure.
--
Otheus
oth...@gmail.com
+43.699.1049.7813
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