Re: [AMaViS-user] Berkeley DB blocking during heavy load?

On Wed, Apr 06, 2005 at 04:43:41PM -0400, John Morrissey wrote:
> On Wed, Apr 06, 2005 at 01:39:37AM +0200, Mark Martinec wrote:
> > > I'm running amavisd-new 20040701-1
> >
> > I suggest 2.2.1 for production use.
>
> Ok, I'll start looking at upgrading.
>
> > > on some large-ish machines (dual 3GHz CPUs, 4GB RAM) doing virus
> > > filtering only. Under high load (more than a couple dozen amavisd
> > > processes active),
> >
> > Did you arrive at the optimum number of processes by measuring throughput?
>
> That's the gist of what we're trying to do, but we can't come up with an
> honest number when there is so much lock contention. They obviously have
> more horsepower available (plenty of RAM available, state is stored on a
> tmpfs so very little disk I/O is involved, and plenty of CPU remaining, just
> a lot of processes spinning on lock acquisition).

I suspect you might wind up with better CPU utilization with fewer
processes. Off the cuff, in postfix content filter mode, I think 10-12
concurrent processes should keep SA busy soaking up all the CPU it can
get.

BTW, unless you are running a large DB on the same machine, it seems
to me 4GB RAM is overkill. (Even with a substantial portion dedicated
to a RAM-based /var/amavis fs.)

[...]
> That begs the question of what happens if the remaining BDB use also causes
> excessive lock contention. The stats will be useful to us, and I'd like to
> have them. Is there any way of alleviating the contention? Do the stats
> modify a single state table? If so, a transactional BDB environment wouldn't
> help, since that code probably needs atomic increments.

(Sorry, can't help on this one.)

-- Clifton

--
Clifton Royston -- cliftonr@tikitechnologies.com
Tiki Technologies Lead Programmer/Software Architect
"I'm gonna tell my son to grow up pretty as the grass is green
And whip-smart as the English Channel's wide..."
-- 'Whip-Smart', Liz Phair


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