How to configure AQUA mt tasks to run on less than the total number of CPU cores

[kashi]

The AQUA mt (multi-threaded) application by default will use all the cores of a single socket computer. This gives the greatest efficiency and highest rate of credit when running AQUA. However some may wish to run AQUA on less than all the cores available.

The reasons for this may include enabling more CPU support for running video card based projects, running a favourite CPU project on one or more of the cores at the same time as AQUA, leaving a core free for greater computer responsiveness for non-BOINC applications (yes, yes, I know, but there really are some who use their computer for applications other than BOINC :)), enabling cooler running on a computer that is overheating due to inadequate cooling/hot weather or stopping AQUA hogging resources by not sharing properly according to the BOINC resource share that has been set.

To do this it is necessary to reduce the number of cores allocated to BOINC before downloading an AQUA task:

On the "Your account" page of a project you are currently attached to click "Computing preferences" in Preferences section. Then click "Edit preferences" near bottom. In Preferences section in box next to "On multiprocessors, use at most Enforced by version 6.1+" change the 100% to the percentage of cores you wish to allocate to AQUA, for example set 75% to use 3 cores of a quad, or 87.5% to use 7 cores of a Nehalem. Click "Update preferences" box near the bottom of the page and wait until the page refreshes with the red writing at the top. Leave the webpage open, we will return to it later. Then in BOINC Manager highlight the project on which you have changed the preferences and click "Update" Command box. Check in messges tab and you should see the number of BOINC cores change to what you had set, BOINC will run CPU Benchmark when number of cores change. Then highlight AQUA and click "Allow new tasks" command button and you should download 2 AQUA tasks if your cache settings are large enough. These AQUA tasks will run on the reduced number of cores you currently have set. Now go back to the webpage we left open and use the same method as before to change back to 100% CPU cores. Then back to BOINC Manager and Update the project again and BOINC will change back to using all cores, AQUA will remain using the reduced number of cores and you will be left with core(s) free to do with as you will. 

You need to follow this procedure every time before you download a new AQUA task, otherwise the new task and any remaining in your cache will change back to using the full number of CPU cores.

[veebee]

this process doesn't change existing WU's to run on 7 cores does it ?

I just tried it and it didn't even notify of changes in the messages tab..

EDIT: just did the "update" on the q6600 and IT dropped down to 3 cores... but the i7 still wont go down to 7..

[veebee]

just realised it was coz I didn't get a new WU to download on the i7..but now it wont give me another 1  ! hahah


EDIT - AGAIN: OK, did the "re-setting" of preferences again and got it to download another WU..but stil running on 8 "cores"..   :cry2:



EDIT - FINAL I HOPE:  OK, I have it now running on 7 cores for AQUA. problem is, BOTH AQUA WU's start running !

[kashi]

Yes you have to suspend the 2nd AQUA task until the first one is finished. It was an oversight on my part not mentioning that, I am so used to it that I took it for granted.

The 200-8 tasks run for so long that if you will be away from your computer or asleep when the first task is due to finish just suspend it and switch to processing the second task instead. The long run time gives a fair bit of scope to juggle the finishing times of both tasks to suit your schedule. You have to be present to switch back to a lower number of cores anyway before you download another task, so there is not really much extra babysitting involved.

For example I now have an AQUA task that is due to finish at 4am, so I will suspend it and switch to the 2nd task before I go to sleep. Sometime tomorrow I will switch back and complete the first task. I use the same procedure if I am going out for the day and an AQUA task is due to finish in that time. If you are very busy, away from home for very long periods or have a large farm this may not be convenient but many people would be able to manage it without much trouble.

Personally I find the long and consistent run times of AQUA tasks require much less supervision than when I am doing a bit of WCG which requires frequent checking in case it is using all 8 cores and preventing MilkyWay ATI running or only running on 6 or 5 cores with 1 or 2 cores on MIlkyWay ATI in "running idle" mode.