climateprediction.net home page
Swapping makes computer unusable

Swapping makes computer unusable

Questions and Answers : Preferences : Swapping makes computer unusable
Message board moderation

To post messages, you must log in.

AuthorMessage
old_user182684

Send message
Joined: 16 Apr 06
Posts: 4
Credit: 0
RAC: 0
Message 22175 - Posted: 18 Apr 2006, 20:59:02 UTC

I\'ve installed BOINC as an XP service on two student machines in my office over the weekend, and attached to CPDN. Both are P4 3.0, 512MB, plenty of disk. Both students came to me this morning because their machines were unusable - they were constantly swapping memory. The process list (which took around two minutes to get itself enough memory to display) showed two CPDN processes each using between 250 and 400MB of VM, constantly swapping in and out with wildly fluctuating physical memory usage. Suspending one wouldn\'t help - the other one would still drain the machine, whether the user tried to work on it or not.
I\'m using the standard preferences (which I thought should keep the process reasonably \"backgroundy\") - anyone with similar problems, and how did you fix it?
ID: 22175 · Report as offensive     Reply Quote
Profile Pooh Bear 27
Avatar

Send message
Joined: 5 Feb 05
Posts: 465
Credit: 1,914,189
RAC: 0
Message 22176 - Posted: 18 Apr 2006, 21:09:51 UTC

One suggestion, add more memory. Also see what else might be running at the same time. None of my machines have less than 768M of memory. The two that can do 2 CPDN simutaneously have 1G of memory and I do not get the swap issues.


ID: 22176 · Report as offensive     Reply Quote
old_user182684

Send message
Joined: 16 Apr 06
Posts: 4
Credit: 0
RAC: 0
Message 22177 - Posted: 18 Apr 2006, 21:27:14 UTC - in response to Message 22176.  

Adding more memory is not an option, because there\'s no budget. The idea was to donate idle CPU cycles, not setting up dedicated CPDN machines.

The memory requirements _for_the_machine,not_the_model_ are listed as \"at least 256MB, recommended 512\". What else is running at the same time? Well, there are people *working* on the machine. Matlab, Eclipse, Openoffice, Firefox. I\'d expect BOINC/CPDN to respect that and refrain from using an amount of virtual memory larger than the available physical memory (which is stupid anyway) if somebody is typing away on the machine at the same time.

Is \"surrender your whole machine or detach\" really the only choice I have? The old CPDN models were a bit more reasonable in that respect.

ID: 22177 · Report as offensive     Reply Quote
Les Bayliss
Volunteer moderator

Send message
Joined: 5 Sep 04
Posts: 7233
Credit: 23,154,247
RAC: 170
Message 22180 - Posted: 18 Apr 2006, 22:12:33 UTC

Minimum recommended amount of ram is now 512Megs. This has been fixed on the BBC site, but apparently overlooked here. I\'ll pass it on to be changed.

There should be two \"processes\" in Task Manager: one the worker, using a fair bit of memory, the other the gui, using little to none.
If you have two of each, then you most likely have two models running on a HT machine.

In which case, you should go into your general preferences, (Click on Your account in the blue menu to the left of here), and set: On multiprocessors, use at most
to a value of one. Then Suspend one of the models. Or Abort it.


ID: 22180 · Report as offensive     Reply Quote
old_user182684

Send message
Joined: 16 Apr 06
Posts: 4
Credit: 0
RAC: 0
Message 22182 - Posted: 18 Apr 2006, 22:28:14 UTC - in response to Message 22180.  

There are two models running (otherwise the CPU would only be 50% loaded). But as I said, suspending/aborting one of them wouldn\'t help, because one alone would still render the machine unusable for other work.

If the recommendation is 512MB min, it should be stated somewhere that this amount will not allow much else than CPDN and the operating system on the machine before it goes into perma-swap. I\'d actually call it \"minimum requirement\", not \"minimum recommendation\" (which should be >=1G then, at least for non-dedicated machines)

Is there really no way of forcing the model towards more cooperative behaviour?
ID: 22182 · Report as offensive     Reply Quote
Profile astroWX
Volunteer moderator

Send message
Joined: 5 Aug 04
Posts: 1496
Credit: 94,916,150
RAC: 20
Message 22183 - Posted: 18 Apr 2006, 23:49:59 UTC

Memory 502.07 MB suggests to me thatthere is no video card in the machines, only a video chip on the Motherboard. In which case, video memory is carved from system memory, hence, it isn\'t reported as 512 Meg and there is even less available for other work.

Are these students running graphics-intense software? If so, that would explain the extensive thrashing but, unless locked, not unusable.

I think the Models ARE trying to stay in the background but a machine with insufficient resources will consume a lot of time trying to do what you want it to do.

If you set \"No new work\" and then suspend one Run, that will cut down on the conflict.

Windoze may claim that the CPU is only running at 50% but that is because it thinks it is dealing with two CPUs. In fact, you get about 85% using a single side of the HT CPU. With the CPU still set to use HT, the remaining facility is available for whatever else you choose to run and CPDN is designed to get out of the way.

My experience with HT CPUs suggests that you try to run a single Model. Your supposition may then be changed. In any event, a machine with a CPU that powerful is memory-starved for many applications.
"We have met the enemy and he is us." -- Pogo
Greetings from coastal Washington state, the scenic US Pacific Northwest.
ID: 22183 · Report as offensive     Reply Quote
Les Bayliss
Volunteer moderator

Send message
Joined: 5 Sep 04
Posts: 7233
Credit: 23,154,247
RAC: 170
Message 22184 - Posted: 18 Apr 2006, 23:51:16 UTC

Boinc is a low priority background process. If/when another program wants the resources, then it gets them. How long it takes will depend on how much swap space is being used, and whether the computer is in the middle of a swap at the time.


ID: 22184 · Report as offensive     Reply Quote
old_user182684

Send message
Joined: 16 Apr 06
Posts: 4
Credit: 0
RAC: 0
Message 22186 - Posted: 19 Apr 2006, 0:29:33 UTC - in response to Message 22183.  

The graphics is most likely on-board, but 10MB shared memory more or less are not causing the problem here. The problem is two orders of magnitude bigger. In fact, you can let the machine sit after boot, without any users logging in (BOINC service started on boot though), and the swap orgy will start soon after. If you then press ctrl-alt-del, it can take up to a minute of swapping only to free enough memory for the damn password prompt to appear.

512MB is pretty much what Joe Sixpack gets when he buys a plain vanilla computer these days. If I look at our intranet, it is what our IT dept considers its \"standard computer\" (we\'re a research institute). The point of my question is: Is it possible to change CPDN\'s settings in a way that such a standard computer will be usable for ANY other work if CPDN is running in the background? Having to wait 10s between any two keystrokes in Word - because parts of Word are constantly swapped out - does not qualify for usability. And if 512MB is too little for this requirement, please change the website and don\'t call it the \"recommended amount of memory\".

@Les Bayliss: Yes, but that\'s the whole point. \"How long it takes will depend on how much swap space is being used\" - exactly. CPDN takes more or less all physical memory on a 512MB machine, so all foreground work will slow down to a crawl because of swapping. _How_do_I_change_that_if_possible?_
ID: 22186 · Report as offensive     Reply Quote
Les Bayliss
Volunteer moderator

Send message
Joined: 5 Sep 04
Posts: 7233
Credit: 23,154,247
RAC: 170
Message 22187 - Posted: 19 Apr 2006, 0:40:25 UTC

I don\'t think that it IS possible. BOINC\'s function is to use ALL available spare clock cycles for the DC project(s).

There is a program called Threadmaster that somehow reduces the amount of clock cycles being used.
I don\'t know much about it, only what people have posted:
It slows down all my programs
It has a very complicated setup

You can get a copy from a link in the blue menu to the left, under: Add-ons




ID: 22187 · Report as offensive     Reply Quote
John McLeod VII
Avatar

Send message
Joined: 5 Aug 04
Posts: 172
Credit: 4,023,611
RAC: 0
Message 22192 - Posted: 19 Apr 2006, 2:30:30 UTC

CPDN uses only the RAM that it absoloutely needs in order to run. There is no way of reducing the amount of RAM that CPDN uses.

If CPDN is swapping too much, I would suggest the only recourse is to detach and try some other BOINC projects (NOT BURP as their RAM requirements are even higher).


BOINC WIKI
ID: 22192 · Report as offensive     Reply Quote

Questions and Answers : Preferences : Swapping makes computer unusable

©2020 climateprediction.net