Paper: Scalability by Design - Coding for Systems With Large CPU Counts

The multi-cores are coming and software designed for fewer cores usually doesn't work on more cores without substantial redesign. For a taste of the issues take a look at No new global mutexes! (and how to make the thread/connection pool work), which shows some of the difficulties of making MySQL perform on SMP servers.

In this paper, Richard Smith, a –Staff Engineer at Sun, goes into some nice detail on multi-core issues. His take home lessons are:

Use fine-grained locking or lock-free strategy

Document the strategy, including correctness
criteria (invariants)

Keep critical sections short

Profile the code at both light and heavy load

Collect HW performance counter data

Identify bottleneck resource (there's always at least one!)

Eliminate or ameliorate it

Comments

[geekr]

Hardware Transactional Memory uses processor features to detect conflict between two
concurrent threads and choose one of them to be aborted. There is no slowdown if there is no
conflict.
One reason for Sun's interest in Transactional Memory is that the capability is being
designed into its future Rock processor.
This is promising! Thanks Todd.