Message boards : Questions and problems : Multi-Threaded Apps
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![]() Send message Joined: 29 Aug 05 Posts: 15585 ![]() |
You can limit the number of threads in the cc_config by adding this <ncpus>48</ncpus> The <ncpus/> configuration option tells BOINC that you want to test use that many CPU cores, even when you don't have them. Doing this on e.g. a quad core CPU will start 48 instances of science applications, massively slowing down everything in the computer. Not really a good idea or advice in this. |
Send message Joined: 5 Oct 06 Posts: 5143 ![]() |
Maybe I'm misunderstanding, but hopefully I'm not. Multi-threaded apps (tasks running on more than 1 core) use OpenCL to do so. This basically helps the task complete faster by using parallel processing instead of serial. That is only one possible example, out of many. The BOINC programming manual refers to You may be able to use OpenCL, MPI, OpenMP, ​CUDA, languages like Titanium or Cilk, or libraries of multi-threaded numerical "kernels", to develop a multi-threaded app. In general on this forum, we refer to OpenCL when we mean OpenCL, and multi-threaded when we mean one of the others - most commonly OpenMP. |
![]() Send message Joined: 29 Aug 05 Posts: 15585 ![]() |
In general on this forum, we refer to OpenCL when we mean OpenCL, and multi-threaded when we mean one of the others - most commonly OpenMP. I have to give it to SuperSluether that projects can make use of OpenCL to make their multi-threaded applications, and that we can refer to it as that. OpenCL isn't GPU only, it's capable of running on anything that can do calculations and has OpenCL support, so in theory also the processor in a NIC or Soundcard. Support for OpenCL on CPUs is already in BOINC and I think I saw that support for non-CPUs is about to be introduced in 7.5 |
Send message Joined: 20 Jun 14 Posts: 11 ![]() |
You can limit the number of threads in the cc_config by adding this <ncpus>48</ncpus> <ncpus>48</ncpus> was just an example I use that to limit a 64 core machine to 48 cores when running multil threaded WU's. You can put however many cores you want to use there <ncpus>3</ncpus> when you are running muti threaded work. |
![]() Send message Joined: 29 Aug 05 Posts: 15585 ![]() |
<ncpus>48</ncpus> was just an example I use that to limit a 64 core machine to 48 cores when running multil threaded WU's. You can put however many cores you want to use there <ncpus>3</ncpus> when you are running muti threaded work. You might be using it for that, but it's not what it is there for. Since you just said earlier that you set it like that and that that works for you, without telling anyone at the time that you have the amount of CPUs to work with, I only explained what the option does and why it's then bad advice to tell people to use it like that. Not everyone has 64 CPUs or cores. Someone with only 1, 2, 3, 4, 6, 8, 10, 12 cores will overload his machine with 48 tasks running simultaneously. http://boinc.berkeley.edu/wiki/Client_configuration <ncpus>N</ncpus> Act as if there were N CPUs; e.g. to simulate 2 CPUs on a machine that has only 1. To use the number of available CPUs, set the value to -1 (was 0 which in newer clients really means zero). |
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