DB_THREAD support in Berkeley DB/glibc

[Geoff Keating]

> Date: Tue, 28 Dec 1999 19:15:59 -0500
> From: David Edelsohn <dje@watson.ibm.com>

You were right about sync being slower than isync.  I expect
the difference is caused by sync needing to perform bus operations
where isync does not.

Anyway, they're not substitutes for each other; they do different
things, and in a given situation only one (or, possibly, both in
sequence) will be right.

> 	If you only are using the TSL_UNSET in the context that one
> already has the lock, then the lwarx/stwcx are unnecessary.  What you have
> written, however, is not a general atomic clear macro.

How is it not atomic?

The PUM says "With the exception of double-precision floating-point
accesses on 32-bit implementations, all aligned accesses are atomic."

-- 
- Geoffrey Keating <geoffk@cygnus.com>