Originally the app part of the runtime system polled for messages every 1 sec.
At some point (several years ago) I changed this to 0.1 sec.
Throttling uses 1-sec resolution to be compatible w/ old apps.
Note: "1-sec resolution" means the shorter of the 2 intervals
(on and off) is 1 sec.
E.g. 25% throttle is 1 sec on, 3 sec off.
Also: the throttling mechanism turns all jobs on/off, as a unit.
So 2 changes are possible:
1) change the resolution to 0.1 sec if all apps have recent API libs.
2) "stagger" the throttling of jobs
... or a combination of the 2.
1) has the disadvantage that stopping/starting some jobs
(e.g. multi-process) can have large-ish overhead
On 28-Feb-2013 9:29 AM, Kevin Reed wrote:
> David,
>
> I have a question about the throttle. At one point Peter Hanappe had worked
> on
> this draft paper which I understand he already shared with you:
>
> /(See attached file: hanappe-slow-computing.pdf)/
>
> In it he describes the power saving benefits of changing the throttling
> mechanism to 'fine grained throttling'.
>
> Additionally, we are periodically in discussions with the support desk about
> WCG
> running on laptops in the organizations. We tell them that we limit the cpu
> use, but they report that the cpu use jumps around and interferes with other
> applications and since they see it jumping around they ignore our statements.
>
> Additionally, I get feedback like this "Just ran the nightly installer for
> Ubuntu 13.04 [Raring Ringtail] onto my 64GB USB 3.0 memory drive and pulled
> BOINC 7.0.27 from the repository. Connected WCG and had it load 8 HCC1.
> Installed GKrellm to monitor temps. Set prefs to 50% CPU time, AND most
> importantly, set Run Based on Preferences. Gkrellm shows a seasaw load and
> temperatures alternating between 88C and 75C every other second. 88C is
> unacceptable, 75C would be borderline. As I wrote before, I'd have to lower it
> to 25% to get the top temp to go below 75C... preposterous and could as well
> not
> run BOINC. Then switch to % of processors and set that to 50%. Continous top
> temp of 93C which is not acceptable at all, Fan is going full-out.
>
> Installed CPUFreq and knocked it down to 2.5 Ghz. The top temp is now 75C and
> bottom 62C with a 50% CPU time setting. "
>
>
> Based on this, I've seen the following requests:
>
> * The interval for which the % runtime is computed needs to be much smaller
> than it is now. At least less than a second, and given Peter's work,
> perhaps it should be dynamically chosen based on the clock frequency of
> the
> processor. Even if we can't get it to achieve the power saving settings
> Peter identified, it would be good so that there isn't thermal cycling
> like
> we are seeing reported. Additionally, when people use tools such as top
> or
> task manager should see an even pacing steady % cpu use and not a usage
> that
> is jumping around.
> * We are getting a lot of feedback that % runtime should be separately
> controllable for GPU tasks and CPU tasks.
>
>
> What are your thoughts?
>
>
>
> Kevin Reed
> . . . . . . . . . . . . . . . . . . . . . . . . .
> i b m i n t e r a c t i v e:: c h i c a g o
>
> 312 529 2802 office
> [email protected] email
>
>
> /You can also donate your computer's unused time. Visit
> //http://www.worldcommunitygrid.org// to learn how./
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