If you ever try to run a high load mysql on amd64 with Debian-Sarge: Forget it.

After many hard days, we found this:

http://bugs.mysql.com/bug.php?id=8555
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=314408

Switching to 32Bit mode works, but there is a loss of 10-20% performance :(

No we have a new problem - when we get close to 4000qps, we ran out of threads:
ERROR 1135 (00000): Can't create a new thread (errno 12); if you are not out of available memory, you can consult the manual for a possible OS-dependent bug

I now wait for a call from MySQL AB.