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Re: DB_THREAD support in Berkeley DB/glibc
- To: dje at watson dot ibm dot com
- Subject: Re: DB_THREAD support in Berkeley DB/glibc
- From: Geoff Keating <geoffk at cygnus dot com>
- Date: Tue, 28 Dec 1999 16:54:38 -0800
- CC: eek at escape dot ca, drow at false dot org, linuxppc-dev at lists dot linuxppc dot org, libc-alpha at sourceware dot cygnus dot com
- References: <199912290015.TAA24316@mal-ach.watson.ibm.com>
> 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>