Question about setting cpu/core priority

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Question about setting cpu/core priority

Postby PFM » Sun Jan 04, 2009 9:44 pm

Hi, first time user here. I am running the Systray 6.23 client on Win XP Pro SP3.
I have a question about the 'Core Priority' setting. Switching between the 'lowest' and 'slightly higher' setting I was expecting to see the task's priority in the windows Task Manager to change. Like from Low to Below Normal or Normal or something. But I didn't see that change.
So either I am not understanding the purpose of this option correctly, or maybe its not working correctly.

Either way, would it benefit the FAH process to manually change the priority of the two tasks (Folding@Home.exe and FahCore_78.exe) to something higher than Low ?
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Re: Question about setting cpu/core priority

Postby spazzychalk » Sun Jan 04, 2009 10:12 pm

no it would be counterproductive. the idea is that all other processes start in normal priority, so anything you do the coomputer gives you the resources to do it and only uses what youre not using at that second to fold. the main idea is that it just runs in the background you never even know its there. if people have to compete with it for things they want to do on the computer theyll just shut it off and forget to shut it back on or get so mad they remove it from the system. just leave it on low and it will use whatever is leftover. the set it and forget it method.

when youre in crontrol alt delete or control shift escape to the task manager, you can go to the processes tab, and organize by cpu usage. here you can watch in real time as the core give back and takes system resources. if you raise the priority to normal you get into paging conflicts that lead to thrashing.
Last edited by spazzychalk on Mon Jan 05, 2009 5:16 pm, edited 1 time in total.
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Re: Question about setting cpu/core priority

Postby toTOW » Sun Jan 04, 2009 11:02 pm

When you change between low (slightly higher) and idle (lowest) settings, it doesn't show up in the task manager, but there is a change. You can only see it with more powerful tools (like Process Explorer) which will display detailed thread informations, and you'll see that the processing thread priority change. Windows Task Manager only shows processes.

There's not benefit to manually change process priority for two reasons :

- if you set it too high, you'll loose control on your system (never try High or Real Time settings :roll: )
- manual setting will be lost each time you restart the client, or each time you start a new WU.
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Re: Question about setting cpu/core priority

Postby spazzychalk » Sun Jan 04, 2009 11:19 pm

you can see the priorities in task manager in the processes window you right click the process and set priority and theres a bullett next to the one its on now
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Re: Question about setting cpu/core priority

Postby toTOW » Sun Jan 04, 2009 11:32 pm

No spazzychalk, you're wrong. Priorities set in the client configuration are not the same as those shown in task manager.

Here is an example (look carefully at the Base Priority field) :

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Fahcore_a1 is set at lowest (idle) priority in the client settings, and shows as low priority in task manager. Thread Base priority = 1.
Fahcore_12 is set at slightly higher (ilow) priority in the client settings, and shows as low priority in task manager too. Thread Base priority = 4.
vmware-vmx is a regular software and it shows at normal priority in task manager. Thread Base priority = 8.

This concept (thread base priority) is easier to understand under Linux, as the "top" utility displays these values by default (PR and NI values are the equivalents of "thread base priority" and priority shown in task manager).
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Re: Question about setting cpu/core priority

Postby PFM » Mon Jan 05, 2009 2:17 am

so in general thread priority take precedence over process priority ?

Here's something I experienced when I was tinkering around with it -
When the "Lowest Possible" option is selected, it does not have any negative effect on the PC even when the process priority is changed all the way to "High" in the task manager. But when the "Slightly Higher" option is selected even changing it to Normal in the task manager slows the whole system down considerably.

For 'advanced users' who want to maximize cpu availability to FAH by manually finding a point where it does not interfere with the rest of the system, and wouldn't mind doing that everytime the client is started, what do you suggest they could do ?
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Re: Question about setting cpu/core priority

Postby bruce » Mon Jan 05, 2009 7:24 am

PFM wrote:For 'advanced users' who want to maximize cpu availability to FAH by manually finding a point where it does not interfere with the rest of the system, and wouldn't mind doing that everytime the client is started, what do you suggest they could do ?


The real question here is what tasks are you running that you want to have a lower priority than FAH? How about simply not running those tasks -- or assigning them to "IDLE" priority so they can't get done.

In general, all tasks can be divided into two types -- ones which run very briefly and then have to wait for something (I/O, such as you to type or a disk to respond, etc.) and ones which will use large amounts of processing without needing to wait for anything. (FAH is relatively rare because it falls into the latter category.) Tasks that use small amounts of processing and large amounts of I/O should have priority over tasks that need large amounts of processing and small amounts of I/O. Those tasks that do mostly I/O rarely use enough processing time to slow FAH down.
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Re: Question about setting cpu/core priority

Postby Longbowgun » Mon Jan 28, 2013 3:52 am

I am looking to change the priority on several older cpu only machines. They are sitting in the garage doing nothing but folding. How do I set them to make that the top priority? I remember seeing something somewhere about setting flags. Will it make a difference?
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Re: Question about setting cpu/core priority

Postby art_l_j_PlanetAMD64 » Mon Jan 28, 2013 5:31 am

Longbowgun wrote:I am looking to change the priority on several older cpu only machines. They are sitting in the garage doing nothing but folding. How do I set them to make that the top priority? I remember seeing something somewhere about setting flags. Will it make a difference?

It should not make any difference. The folding tasks/threads should be getting almost 100% of the CPU time, only a small amount would be getting used up by your OS (Windows or Linux) with background tasks/interrupts.
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Re: Question about setting cpu/core priority

Postby bruce » Mon Jan 28, 2013 5:50 am

Right. If nothing else is running, FAH is already the top priority no matter what it's set to.
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Re: Question about setting cpu/core priority

Postby Napoleon » Mon Jan 28, 2013 12:26 pm

I do set NVidia GPU FahCore_1?.exe processes to High priority, though. It can be done automatically by utilities such as Process Lasso. I have other stuff running on my computer, so I want to make sure that NVidia folding gets all the attention from the CPU it needs, and right quick too.
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Re: Question about setting cpu/core priority

Postby JimboPalmer » Mon Jan 28, 2013 3:49 pm

If you run SMP and GPU slots on the same box, set GPU to the 'slightly higher' setting, otherwise leave F@H at lowest.

It will still get ALL the CPU time if no higher priority job runs. Just choose not to run anything else.
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Re: Question about setting cpu/core priority

Postby Longbowgun » Tue Jan 29, 2013 1:09 am

Awesome! Thanks. I am also thinking about changing some of my systems (three Dell GX270s) to Ubuntu to enhance performance. I remember reading that there is about a 5% increase in folding efficiency due to lower OS overhead. Can anyone confirm?


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Re: Question about setting cpu/core priority

Postby art_l_j_PlanetAMD64 » Tue Jan 29, 2013 1:23 am

Longbowgun wrote:Awesome! Thanks. I am also thinking about changing some of my systems (three Dell GX270s) to Ubuntu to enhance performance. I remember reading that there is about a 5% increase in folding efficiency due to lower OS overhead. Can anyone confirm?

I don't know if there's any 'official' data, but my own observations are here:
art_l_j_PlanetAMD64 wrote:I liked the Debian v6.0.6 Linux so much that I installed it on another system as well, so I now have 3 Windows machines and 2 Debian Linux machines folding now. The SMP clients on Linux do seem to be very good, the PPD of the dual-core Linux systems (AMD Athlon II X2 240 and AMD Athlon 7550) sometimes approach the PPD of the quad-core Windows systems (AMD Phenom II X4 955 and AMD Phenom II X4 965), depending on which WUs they get.


Longbowgun wrote:Overall Project user Percentile: 99.02239% Finally made into the top 1% of all users! :D

Congratulations! :D
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Re: Question about setting cpu/core priority

Postby bruce » Tue Jan 29, 2013 7:12 am

Some FahCores are more optimized and do run more efficiently in Linux; others have been no different at all. Most certainly it's not due to OS efficiency. There's no possibility of your Windows components actually taking up 5% of the time even with all the default services that it likes to start up.
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