I've seen of useful, or useful looking books about Solaris
system performance tuning - most of them printed by SUN.
I've found the course material of HP Education quite useful.
System performance tuning is hard, and system specific.
I would distrust any book that claims to discuss system
performance tuning without focussing on a specific OS. I'd
also distrust any "cookbook".
Go for something that spends a lot of time analysing performance
problems, that discusses performance measuring tools (like
glance for HP-UX), and goes into detail explaining
how the system works.