Reducing the activity of the image

Am 09.02.2015 um 21:33 schrieb [hidden email]:

Can't the box be setup 5o do some WoL thing and go back to sleep when idling for a while?

This CPU usage is really annoying indeed.

Phil

Le 9 févr. 2015 21:11, "Norbert Hartl" <[hidden email]> a écrit :

I have an installation where a pharo powered hardware is used in a closed case. Over time that collects quite some heat. One reason for this is that the pharo vm is taking approx. 6% CPU all the time. The only thing that happens is network/sockets. I suspended the ui thread in the image but on this platform it doesn't help.
Are there any tweaks to lower the polling and the activity of the image/vm even more?

thanks,

Norbert

> Am 09.02.2015 um 22:19 schrieb stepharo <<a href="javascript:;" onclick="_e(event, &#39;cvml&#39;, &#39;stepharo@free.fr&#39;)">stepharo@...>:
>
>
>>>> I have an installation where a pharo powered hardware is used in a closed case. Over time that collects quite some heat. One reason for this is that the pharo vm is taking approx. 6% CPU all the time. The only thing that happens is network/sockets. I suspended the ui thread in the image but on this platform it doesn't help.
>>>> Are there any tweaks to lower the polling and the activity of the image/vm even more?
>>> Right now having an event driven VM is the way but it is not on the horizon. JB was starting to look at that when he worked on the android part.
>> Are the prerequisites for having things event driven known? Is that a huge task for the vm if things need to call in instead of being called?
>
> I do not know. What I can tell you is that we are doing our best and I'm try to get funding.
> This is three years that I apply to EU funding and fail :). But if I get it I have 8 years engineers planned.

I know is hard. Thank you very much to try harder :)

We'll make it somehow ;)

Norbert

Am 10.02.2015 um 09:23 schrieb Clément Bera <[hidden email]>:

Hello,

About the Morphic rendering loop, the delay between rendering is handled in WorldState>>#interCyclePause:. The best solution to reduce the cost of the Morphic rendering loop is to put it in server mode by executing in Pharo: WorldState serverMode: true. In squeak you have to set that in the Preferences.

But as it was discussed, the cpu consumption most probably does not come from Morphic but comes from the idle loop, which can be solved by doing an event-driven VM. 

I am particularly willing to have an event-driven VM because it then means that the VM performance would then be directly proportional to the cpu consumption. For example, theoretically, with an event-driven VM, having the VM twice faster with Spur would also mean that the VM consumes twice less energy. Go Green IT :-)

2015-02-10 8:00 GMT+01:00 Eliot Miranda <[hidden email]>:

On Feb 9, 2015, at 10:41 PM, Sven Van Caekenberghe <[hidden email]> wrote:

>
>> On 10 Feb 2015, at 01:55, Eliot Miranda <[hidden email]> wrote:
>>
>> Hi Sven,
>>
>> On Mon, Feb 9, 2015 at 1:43 PM, Sven Van Caekenberghe <[hidden email]> wrote:
>> There is some timer thread between the image and the vm that ticks every millisecond, that is the cause. I don't know what it does but it is apparently needed.
>>
>> Anyway, that is how I understood it from Igor and Eliot, long ago.
>>
>> So basically, the VM is always slightly busy.
>>
>> Yet the VM is always slightly busy with the heartbeat thread, but this is very cheap.  The actual idle cost comes form the idle loop in the background process that sends relinquishProcessorForMicroseconds:, which is a primitive that eventually calls the select system call.  This is the source of the cost.
>
> Can we change something about that ?
> Maybe just as an experiment to prove your point ?

What do you think halving or doubling the argument to relinquishProcessorForMicroseconds: should do if this is the major source of overhead?  Processor usage at idle should be closely inversely proportional right?

>
>>> On 09 Feb 2015, at 21:11, Norbert Hartl <[hidden email]> wrote:
>>>
>>> I have an installation where a pharo powered hardware is used in a closed case. Over time that collects quite some heat. One reason for this is that the pharo vm is taking approx. 6% CPU all the time. The only thing that happens is network/sockets. I suspended the ui thread in the image but on this platform it doesn't help.
>>> Are there any tweaks to lower the polling and the activity of the image/vm even more?
>>>
>>> thanks,
>>>
>>> Norbert
>> --
>> best,
>> Eliot
>
>

Am 10.02.2015 um 11:23 schrieb Sven Van Caekenberghe <[hidden email]>:

On 10 Feb 2015, at 11:19, Norbert Hartl <[hidden email]> wrote:

Sven,

Am 10.02.2015 um 10:36 schrieb Sven Van Caekenberghe <[hidden email]>:

On 10 Feb 2015, at 09:51, Norbert Hartl <[hidden email]> wrote:

Am 10.02.2015 um 09:23 schrieb Clément Bera <[hidden email]>:

Hello,

About the Morphic rendering loop, the delay between rendering is handled in WorldState>>#interCyclePause:. The best solution to reduce the cost of the Morphic rendering loop is to put it in server mode by executing in Pharo: WorldState serverMode: true. In squeak you have to set that in the Preferences.

I'll play with it and see what can be gained.

I tried the following on an otherwise idle DigitalOcean VM running Ubuntu 13.10

$ mkdir pharo4
$ curl get.pharo.org/40+vm | bash
$ ./pharo Pharo.image save Server

First patch (slower event handling, extra delay of 50ms):

$ ./pharo Server.image eval --save 'WorldState serverMode: true'

Second patch (give time back to OS while idle for 10ms instead of for 1ms):

$ cat ProcessorScheduler-class-idleProcess.st 
'From Pharo4.0 of 18 March 2013 [Latest update: #40484] on 10 February 2015 at 9:49:15.412839 am!ProcessorScheduler class methodsFor: 'background process' stamp: 'SvenVanCaekenberghe 2/10/2015idleProc[true] w[self relinquishProcessorForMicroseconds: 10000]! !

$ ./pharo Server.image eval "'ProcessorScheduler-class-idleProcess.st' asFileReference fileIn"
$ ./pharo Server.image eval '(ProcessorScheduler class>>#idleProcess) sourceCode'
'idleProcess
"A default background process which is invisible."

[true] whileTrue:
[self relinquishProcessorForMicroseconds: 10000]'

Run an image with a basic Zn HTTP server in background:

$ ./pharo Server.image eval --no-quit 'ZnServer startDefaultOn: 1701' &
$ curl http://localhost:1701

Overall load is 0.01% but this is virtual/shared hardware, so who knows.

CPU load of the pharo process hovers around a couple of %, I am not seeing much difference, maybe it is a bit lower, but that might be wishful thinking.

my findings are similar. I have a CPU usage of 6%. WorldState serverMode adds a Delay for 50ms. Setting a higher number in the idle process does not seem to have any effect until the number is too high, then the image does not start anymore. 
I tuned all of these things and it is not faster sometimes it appears to take more CPU which probably is not true. 

I am afraid that we as a community do not fully understand what is happening or how we can control it.

On the other hand, on a machine with many images running, things are still totally fine, so we should not worry too much. It is only in specific case like yours where it becomes a concern.

Norbert 

But as it was discussed, the cpu consumption most probably does not come from Morphic but comes from the idle loop, which can be solved by doing an event-driven VM. 

I am particularly willing to have an event-driven VM because it then means that the VM performance would then be directly proportional to the cpu consumption. For example, theoretically, with an event-driven VM, having the VM twice faster with Spur would also mean that the VM consumes twice less energy. Go Green IT :-)

That is exactly my point. While consumed energy is turned into heat the act of saving energy is the same as having a cool device (pun intended). 

So I would like to take my consortium hat to state my upvote on this.

Norbert

2015-02-10 8:00 GMT+01:00 Eliot Miranda <[hidden email]>:



On Feb 9, 2015, at 10:41 PM, Sven Van Caekenberghe <[hidden email]> wrote:

On 10 Feb 2015, at 01:55, Eliot Miranda <[hidden email]> wrote:

Hi Sven,

On Mon, Feb 9, 2015 at 1:43 PM, Sven Van Caekenberghe <[hidden email]> wrote:
There is some timer thread between the image and the vm that ticks every millisecond, that is the cause. I don't know what it does but it is apparently needed.

Anyway, that is how I understood it from Igor and Eliot, long ago.

So basically, the VM is always slightly busy.

Yet the VM is always slightly busy with the heartbeat thread, but this is very cheap.  The actual idle cost comes form the idle loop in the background process that sends relinquishProcessorForMicroseconds:, which is a primitive that eventually calls the select system call.  This is the source of the cost.

Can we change something about that ?
Maybe just as an experiment to prove your point ?

What do you think halving or doubling the argument to relinquishProcessorForMicroseconds: should do if this is the major source of overhead?  Processor usage at idle should be closely inversely proportional right?

On 09 Feb 2015, at 21:11, Norbert Hartl <[hidden email]> wrote:

I have an installation where a pharo powered hardware is used in a closed case. Over time that collects quite some heat. One reason for this is that the pharo vm is taking approx. 6% CPU all the time. The only thing that happens is network/sockets. I suspended the ui thread in the image but on this platform it doesn't help.
Are there any tweaks to lower the polling and the activity of the image/vm even more?

thanks,

Norbert

--
best,
Eliot