Issues with threading/SMP (I think?) on Debian-AMD64

[mysql]

I'm compiling my mysql server from source.

I have started noticing this as of 4.1.10 - in fact, I was running 4.1.12 and it's changed the LinuxThreads detection (since LT does not exist on amd64) - and 4.1.12 kept locking up after only a few minutes of uptime consistently.

Once I figured this out, I rolled back to my 4.1.10 with a small patch to the "configure" script to force the calling of CFLAGS="$CFLAGS -DUSE_MUTEX_INSTEAD_OF_RW_LOCKS -DPTHREAD_ADAPTIVE_MUTEX_INITIALIZER_NP"

I'm wondering though - am I missing something here?

What would be the best threading library to call (or command line switch when compiling mysql) on a single processor amd64 machine - as well as a dual processor (SMP) amd64 machine? I have both... and would like to ensure maximum performance on both!

This is my existing configure line:

./configure --prefix=/usr/local/mysql --enable-assembler --without-debug --with-mysqld-user=mysql --without-innodb --without-isam --enable-thread-safe-client --without-extra-tools

Thanks in advance.