[Dovecot] How to get rid of locks
Jim Maenpaa
jim+dovecot at ohwell.org
Sat Apr 7 22:52:19 EEST 2007
On Apr 7, 2007, at 12:30, Timo Sirainen wrote:
> Although Dovecot is already read-lockless and it uses only short-
> lived write locks, it's be really nice to just get rid of the
> locking completely. :)
>
> I just figured out that O_APPEND is pretty great. If the operating
> system updates seek position after writing to a file opened with
> O_APPEND, writes to Dovecot's transaction log file can be made
> lockless. I see that this works with Linux and Solaris, but not
> with OS X. Could you BSD people try if it works there? http://
> dovecot.org/tmp/append.c and see if it says "offset = 0" (bad) or
> non-zero (yay). The O_APPEND at least doesn't work with NFS, so
> it'll have to be optional anyway.
I tested on Mac OS X. Works on Intel (offset = 5), but not PowerPC
(offset = 0)... Both are running 10.4.9.
Kernel versions:
Darwin Kernel Version 8.9.0: Thu Feb 22 20:54:07 PST 2007;
root:xnu-792.17.14~1/RELEASE_PPC
Darwin Kernel Version 8.9.1: Thu Feb 22 20:55:00 PST 2007;
root:xnu-792.18.15~1/RELEASE_I386
-jim
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