Am 27.05.2013 um 10:17 schrieb phil@highoctane.be:
I was looking at the output of "top" for while and Pharo was trusting the top spot indeed.
Well, I'll look at all that this evening and give back the impressions.
I want to run several instances of Pharo on the box and it will for sure add up. Say, 20 x 2% gives an awful lot.
What is the use of having 20 idle images on one server? :) I think you can't easily say that it always adds on top. If your image is running at 100% the 2% off even if fully countable wouldn't be that much. But nevertheless it is a valid point and I cannot see pharo becomes more modern by stop polling in the mid-term future. Anyway I played a little bit with the tweaks and there are things that make me wonder. I raised the limit for server mode but didn't get much benefit. Having a cycle pause of 100ms in serverMode and stopping the ui process still gave me a 1% CPU usage which is really a lot. Does anyone know in-depth what an image is doing? How to investigate? Maybe there are a lot of native polling things involved, too? I need to dig deeper. Norbert
Phil
On Mon, May 27, 2013 at 10:07 AM, Norbert Hartl <norbert@hartl.name> wrote:
Am 27.05.2013 um 09:49 schrieb Sven Van Caekenberghe <sven@stfx.eu>:
BTW, load & cpu usage numbers can be very hard to interpret.
really? CPU usage is pretty easy and you can see this in most OSses directly. 100% CPU usage is full :) Load isn't that much harder. It's just the load of the scheduler queue. So if some needs a rule of thumb
safe CPU load = number of cores/processes * 0.7 theoretical optimal CPU load = number of core/processes
Everything above should really be investigated because you entered the zone where additional CPU load can drive your machine unresponsive. You have less CPU usage but high load? Investigate I/O usage!
I know you know that, Sven. I just wanted to mention it because this comes up from time to time. Compared to memory consumption, CPU, scheduler and I/O are easier targets IMHO.
For Phil the point isn't the health of the system. It is EC2. You have to pay for the CPU usage on EC2 so I think he had the impression there is room for improvement. And indeed there is. But if you calculate it through it isn't really a factor.
Norbert