| Index | Recent Threads | Unanswered Threads | Who's Active | Guidelines | Search |
 |
World Community Grid Forums
Category: Completed Research
Forum: The Clean Energy Project Forum
Thread: Page Faults |
| No member browsing this thread |
|
Thread Status: Active Total posts in this thread: 11
|
|
| Author |
|
|
BigMike
Cruncher USA Joined: Nov 14, 2005 Post Count: 13 Status: Offline Project Badges: 
|
Thanks for the update!
---------------------------------------- While we're waiting, could someone look at the app (WinXP 32bit SP3)? It's generating a huge number (thousands per second) of page faults. And it seems to have nothing to do with available memory ... my system has at least 1GB free while CEP is running. No other grid app I run does this. ==Mike
Don't believe everything you think.
|
||
|
|
Former Member
Cruncher Joined: May 22, 2018 Post Count: 0 Status: Offline |
http://wcg.wikia.com/wiki/Page_faults
----------------------------------------edit: mere thousands per second is unfortunate, but usually not debilitating. [Edit 1 times, last edit by Former Member at Mar 24, 2009 4:22:38 PM] |
||
|
|
David_L6
Senior Cruncher USA Joined: Aug 24, 2006 Post Count: 296 Status: Offline Project Badges: 
|
I guess that's just the nature of beast with CEP. I have a lot of page faults too. OS doesn't seem to matter (XP Home, XP Pro 32 bit, Vista 32 bit, and Vista 64 bit).
---------------------------------------- |
||
|
|
BigMike
Cruncher USA Joined: Nov 14, 2005 Post Count: 13 Status: Offline Project Badges:
|
mere thousands per second is unfortunate, but usually not debilitating. Well, on my system, we're talking about roughly 10,000 per second. If we add together all the systems crunching CEP world-wide, we probably would have quite a few (hundreds? thousands?) CPU's worth of processing power doing nothing but servicing page faults. Just because it's spread out across everyone's systems doesn't make it trivial. Still worth looking at. The grid is all about making small things large enough to matter. ==Mike
Don't believe everything you think.
|
||
|
|
Former Member
Cruncher Joined: May 22, 2018 Post Count: 0 Status: Offline |
The techs decide where their efforts are best expended.
I saw recently a very useful rebuttal of that old saw "every little helps". Yes, every little helps - but only a little bit. In this case, your experience is exceptional, and you haven't even told us what the actual time cost is. Secondly, the problem only affects certain computer/task combinations, so the aggregate effect is even less significant. Do we want to fix it? Of course! This issue is already on the list. But it will have to wait its turn behind more urgent things. |
||
|
|
Former Member
Cruncher Joined: May 22, 2018 Post Count: 0 Status: Offline |
I ran a quick study to see page faults on a linux system with a multi core cpu with the following results:
----------------------------------------Note: I also abbreviated the terminal output of the sar command to reflect only the average page faults/second to keep the post more brief and legible. System: AMD Phenom 9600 2300 MHz with Fedora 10 Page faults per second with BOINC client shut down (system background page faults reference): [roger@starbase2 Documents]$ sudo sar -B 3 4 Linux 2.6.27.19-170.2.35.fc10.x86_64 (starbase2.command) 03/30/2009 09:17:59 AM fault/s Average: 16.37 Running CEP on 0 cores and HFCC on 4 cores simultaneously: Linux 2.6.27.19-170.2.35.fc10.x86_64 (starbase2.command) 03/30/2009 09:25:18 AM fault/s Average: 53.04 Running CEP on 1 core and HFCC on 3 cores simultaneously: Linux 2.6.27.19-170.2.35.fc10.x86_64 (starbase2.command) 03/30/2009 09:23:48 AM fault/s Average: 6525.48 Running CEP on 2 cores and HFCC on 2 cores simultaneously: Linux 2.6.27.19-170.2.35.fc10.x86_64 (starbase2.command) 03/30/2009 09:16:32 AM fault/s Average: 13239.42 It would be interesting to quantify the total time to complete 4 CEP WU's when running simultaneously on 4 cores vs running the same WU's individually on the same single core but one would have to be able to run the WU's twice. [Edit 1 times, last edit by Former Member at Mar 31, 2009 10:36:55 PM] |
||
|
|
Former Member
Cruncher Joined: May 22, 2018 Post Count: 0 Status: Offline |
mere thousands per second is unfortunate, but usually not debilitating. Well, on my system, we're talking about roughly 10,000 per second. If we add together all the systems crunching CEP world-wide, we probably would have quite a few (hundreds? thousands?) CPU's worth of processing power doing nothing but servicing page faults. Just because it's spread out across everyone's systems doesn't make it trivial. Still worth looking at. The grid is all about making small things large enough to matter. ==Mike I have to say he makes a very good point. While Didactylos said that it's on their list, I hope it's not too far behind, because it seems very important considering it could be costing so much cpu power. I mean, for me cep alternates between taking about 1k-2k every few seconds, and other projects like hfcc take maybe 8 every minute. It's defiantly important if you ask me. |
||
|
|
Sekerob
Ace Cruncher Joined: Jul 24, 2005 Post Count: 20043 Status: Offline |
Bluntly, it's economics. CEP takes about 8.6 CPU years for today, 271 CPU years are projected for the other sciences. The resources on WCG side are limited too, though it's costing their side 1.25 million Euro plus annual (actually I think it costs allot more, lots of hidden cost not passed within the large IBM organization), so choices which items to tackle first have to be made. One CEP job at a time does not seem to cause my quad to get saturated, so that's how I run them until a fix is found, probably a needle in a haystack stumbler.
----------------------------------------
WCG
----------------------------------------Please help to make the Forums an enjoyable experience for All! [Edit 1 times, last edit by Sekerob at Mar 30, 2009 6:21:30 PM] |
||
|
|
Former Member
Cruncher Joined: May 22, 2018 Post Count: 0 Status: Offline |
And still nobody has quantified what it actually costs in terms of kernel time.
|
||
|
|
Sekerob
Ace Cruncher Joined: Jul 24, 2005 Post Count: 20043 Status: Offline |
Darn, just see 2 CEP running on the quad: 1 9:47 hours with 14 minutes Kernel time, the other 6:56 hours with 10 minutes.
----------------------------------------
WCG
Please help to make the Forums an enjoyable experience for All! |
||
|
|
|