On Mon, Sep 07 2009, Jens Axboe wrote:
> On Mon, Sep 07 2009, Jens Axboe wrote:
> > > And yes, it would be wonderful to get a test-app from you that would 
> > > express the kind of pain you are seeing during compile jobs.
> > 
> > I was hoping this one would, but it's not showing anything. I even added
> > support for doing the ping and wakeup over a socket, to see if the pipe
> > test was doing well because of the sync wakeup we do there. The net
> > latency is a little worse, but still good. So no luck in making that app
> > so far.
> 
> Here's a version that bounces timestamps between a producer and a number
> of consumers (clients). Not really tested much, but perhaps someone can
> compare this on a box that boots BFS and see what happens.

And here's a newer version. It ensures that clients are running before
sending a timestamp, and it drops the first and last log entry to
eliminate any weird effects there. Accuracy should also be improved.

On an idle box, it'll usually log all zeroes. Sometimes I see 3-4msec
latencies, weird.

-- 
Jens Axboe