[ZODB-Dev] Re: ZODB Benchmarks

[Izak Burger]

Benji York wrote:
> If you're on Linux, you can tweak swappiness (/proc/sys/vm/swappiness; 
> http://lwn.net/Articles/83588/) to affect how much RAM is used for the 
> page cache and how much for your process.

While we're on that subject. We recently had a box that would take 
strain for almost no reason. You'd copy a bigish file from one place to 
another and the load average would just soar as the various zope and zeo 
instances tried to get to the disk. Turns out this machine used the 
anticipatory io scheduler, which really messes things up. We changed it 
to deadline, like so:

   echo deadline > /sys/block/sda/queue/scheduler

Performance is a lot better now. Our (not very scientific) tests shows 
that deadline is also a little better than cfq for running zope.