threading and multicores, pros and cons

[Paul Rubin]

John Nagle <nagle at animats.com> writes:
>     If locking is expensive on x86, it's implemented wrong.
> It's done right in QNX, with inline code for the non-blocking case.

Acquiring the lock still takes an expensive instruction, LOCK XCHG or
whatever.  I think QNX is usually run on embedded cpu's with less
extensive caching as these multicore x86's, so the lock prefix may be
less expensive in the QNX systems.