I'm occasionally seeing processes on my CentOS 4.3 system get hung up, which strace reveals to be waiting on a call to futex(). Previously I'd only ever seen this in mysql on RH9, and google searches for explanations haven't turned up anything useful. Any pointers to where I should look? Is this another one of those things where using the default SMP kernel with a hyperthreaded processor is just a Bad Idea?