Thread '"On multiprocessor systems, use at most % of processors" is inconsistant'

Author	Message
Lucas Dobre Send message Joined: 18 Feb 23 Posts: 40	Message 115468 - Posted: 20 Feb 2025, 13:07:02 UTC Last modified: 20 Feb 2025, 13:07:37 UTC I have 24 cores. I input 100%, it uses 24. I input 99%, it rounds it down and uses 23. I input 91.7 and it rounds it up to 23? 91 rounds up to 22 which I wanted. Hit and miss guesswork. How is it even possible to program it this way?! ID: 115468 · Reply Quote

Dave Help desk expert Send message Joined: 28 Jun 10 Posts: 2809	Message 115469 - Posted: 20 Feb 2025, 13:59:22 UTC - in response to Message 115468. Which BOINC version and OS? Also which CPU. I don't think BOINC code has taken account of efficiency cores yet on Intel CPUs. With my 32 thread (16 real cores) I haven't observed the discrepancy you mention and it always uses as many cores as it can up to the limit so if I set it to 49% it will use 15 cores. The projects I run, using more than half the threads actually cuts down throughput of work so I never go above 50%. ID: 115469 · Reply Quote

Vitalii Koshura Volunteer developer Help desk expert Send message Joined: 29 Mar 17 Posts: 57	Message 115470 - Posted: 20 Feb 2025, 14:39:54 UTC - in response to Message 115468. In reply to Lucas Dobre's message of 20 Feb 2025: How is it even possible to program it this way?! We are highly skilled engineers, and we tried our best. BOINC maintainer. For any insight, check my BOINC Development Blog. ID: 115470 · Reply Quote

Lucas Dobre Send message Joined: 18 Feb 23 Posts: 40	Message 115475 - Posted: 21 Feb 2025, 0:42:02 UTC - in response to Message 115469. In reply to Dave's message of 20 Feb 2025: Which BOINC version and OS? Also which CPU. I don't think BOINC code has taken account of efficiency cores yet on Intel CPUs. With my 32 thread (16 real cores) I haven't observed the discrepancy you mention and it always uses as many cores as it can up to the limit so if I set it to 49% it will use 15 cores. The projects I run, using more than half the threads actually cuts down throughput of work so I never go above 50%. Latest Boinc and Windows. AMD Ryzen 9 3900XT. 12/24 cores/threads. It's just the rounding up and down I find odd. Which is supposed to do? ID: 115475 · Reply Quote

Lucas Dobre Send message Joined: 18 Feb 23 Posts: 40	Message 115476 - Posted: 21 Feb 2025, 0:42:26 UTC - in response to Message 115470. In reply to Vitalii Koshura's message of 20 Feb 2025: In reply to Lucas Dobre's message of 20 Feb 2025: How is it even possible to program it this way?! We are highly skilled engineers, and we tried our best. Nice to see you in here Vitali, only spoken to you in Github. Is it meant to round up or down? ID: 115476 · Reply Quote

Vitalii Koshura Volunteer developer Help desk expert Send message Joined: 29 Mar 17 Posts: 57	Message 115483 - Posted: 21 Feb 2025, 11:36:50 UTC - in response to Message 115476. In reply to Lucas Dobre's message of 21 Feb 2025: In reply to Vitalii Koshura's message of 20 Feb 2025: In reply to Lucas Dobre's message of 20 Feb 2025: How is it even possible to program it this way?! We are highly skilled engineers, and we tried our best. Nice to see you in here Vitali, only spoken to you in Github. Is it meant to round up or down? Actually we just drop the fractional part. So if there will be 11.9999 CPUs to use, we will use 11, not 12. BOINC maintainer. For any insight, check my BOINC Development Blog. ID: 115483 · Reply Quote

Lucas Dobre Send message Joined: 18 Feb 23 Posts: 40	Message 115584 - Posted: 10 Mar 2025, 21:06:00 UTC - in response to Message 115483. Last modified: 10 Mar 2025, 21:08:25 UTC In reply to Vitalii Koshura's message of 21 Feb 2025: In reply to Lucas Dobre's message of 21 Feb 2025: In reply to Vitalii Koshura's message of 20 Feb 2025: In reply to Lucas Dobre's message of 20 Feb 2025: How is it even possible to program it this way?! We are highly skilled engineers, and we tried our best. Nice to see you in here Vitali, only spoken to you in Github. Is it meant to round up or down? Actually we just drop the fractional part. So if there will be 11.9999 CPUs to use, we will use 11, not 12. I input 91.7% (equates to 22.008 CPUs) and it rounded it up to 23. Although I've just tried it again and got 22. I guess I missed something like a high priority task, my fault. ID: 115584 · Reply Quote

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