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Number crunching :
How can I change the number of CPU used by LHC
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Author | Message |
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Send message Joined: 24 Jul 05 Posts: 17 Credit: 2,356,416 RAC: 399 |
Is there a way to change the number of CPU used by LHC after the job has already been downloaded but before the job starts running? I've had nothing but trouble getting projects that use VM to play nicely together and have decided to download one job at a time for one project at a time and strictly limit the resources used. |
Send message Joined: 15 Jun 08 Posts: 2411 Credit: 226,328,504 RAC: 131,924 |
LHC's vbox WUs use 1 core, except ATLAS. To limit ATLAS to 1 core set the project's web preferences to max # CPUs = 1: https://lhcathome.cern.ch/lhcathome/prefs.php?subset=project As some ATLAS batches need more RAM than it is defined by default settings, you may also use this app_config.xml <app_config> <app> <name>ATLAS</name> <max_concurrent>1</max_concurrent> </app> <app_version> <app_name>ATLAS</app_name> <plan_class>vbox64_mt_mcore_atlas</plan_class> <avg_ncpus>1.0</avg_ncpus> <cmdline>--nthreads 1 --memory_size_mb 4800</cmdline> </app_version> </app_config> |
Send message Joined: 14 Jan 10 Posts: 1280 Credit: 8,489,751 RAC: 1,925 |
After adjustments in the app_config.xml, you have to 'Read config files' from the Options menu in BOINC Manager, before starting the new jobs. |
Send message Joined: 27 Sep 08 Posts: 807 Credit: 652,242,820 RAC: 285,643 |
It should be possible via the web configurations, probably Max # CPU = 1 (you might have to set jobs too) |
Send message Joined: 24 Jul 05 Posts: 17 Credit: 2,356,416 RAC: 399 |
First - not to forget my manners - many thanks to those of you who took a moment to give me a hand. I genuinely appreciate your help. I cut-and-pasted the app_config file provide by computezrmle into notepad.exe and created a file I named app_config.xml in the lhcathome.cern.ch_lhcathome directory. I then returned to BOINC Manager, selected the lhc@home project, and invoked 'Read config files' from the BOINC Manager Options menu. I immediately received this error message in the Notices tab: LHC@home: Notice from BOINC Missing <app_config> in app_config.xml The <app_config> phrase shows quite clearly as the very first line in the app_config file I created. So - what did I do wrong? |
Send message Joined: 15 Jun 08 Posts: 2411 Credit: 226,328,504 RAC: 131,924 |
Check if you copy-pasted the first "<" and add a blank line at the end of the file. Then reload it again. |
Send message Joined: 8 Mar 15 Posts: 12 Credit: 1,346,755 RAC: 0 |
One of my "Theory Simulations" tasks have used 15 cores (I have a Ryzen 7 1700, 8 cores 16 threads set to do 15 tasks simultaneously). How can I set Theory tasks to use only 1 core? ASUS X570 E-Gaming AMD Ryzen 9 3950X, 16 core / 32 thread 4.4 GHz AMD Radeon Sapphire RX 480 4GB Nitro+ Nvidia GTX 1080 Ti Gaming X Trio 4x16 GB Corsair Vengeance RGB 3466 MHz |
Send message Joined: 18 Dec 15 Posts: 1688 Credit: 103,752,516 RAC: 122,129 |
On your Preferences page, simply set Max # CPUs to "1" then click on the "Update" button right underneath, and also in the BOINC Manager -> Projects -> LHC click on the "Update" button. So, only 1 CPU core will be used, for all tasks you download from then on. |
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