Hello.
I do have one question.
In The Amicable Numbers preferences, there is an option for number of CPUs.
Does this equate to how many cores get used per task? E.g. if I set it to 8 CPUs 8 out of 16 threads will be used on this Ryzen?
thanks.

Hi wolfman1360,

You are correct that it is the number of cores used per task. If you set it to 8 CPUs, but leave BOINC's CPU usage at 100%, it will have the effect of running two tasks at the same time with 8 threads each. I do this on my Ryzen 5 1600X so that I can pause tasks if I need some CPU power for something else, without having to stop all crunching for Amicable Numbers. I have my 1600X set up to run tasks with 3 threads each, so that I can easily change how much of my CPU is being used (0%, 25%, 50%, 75% or 100%) whenever convenient.

If you would like to limit your computer to running just a single task with 8 threads you can do that in the options here by limiting that computer to only having 1 workunit at a time, setting CPU usage to 50% in BOINC, or by making an app_config file with the following in it;

<app_config>
<app>
<name>amicable_10_20</name>
<max_concurrent>1</max_concurrent>
</app>
</app_config>

Hope this helps!

Regards,
Kellen

Hi wolfman1360,

You are definitely correct about the RAM usage right now! The total RAM used is approximately 650MB per thread, so if you are running 16 threads on you 1800X that would get you into the 10GB neighborhood. This is also a by-product of the present search stage, where we are looking at candidates containing very large prime numbers. RAM usage will continue to climb gradually until the end of the search to 10^20, but will drop significantly once 10^21 search begins.

To the best of my knowledge there are presently no test applications running, so I don't think enabling that would do anything right now. It might if Sergei gets the 10^21 app loaded and tested before 10^20 is complete, but I would expect that is some time off and would only be for a short while.

Nothing really to keep in mind with multi-threading for this project. The multi-threading implementation is pretty straightforward and tends to work well with default settings. Something to note though is that if you are running a task with a set number of threads, lets say 16, and you set CPU usage in BOINC to 50% on your 1800X, the 16-thread task will continue to run with 16 threads, using 100% of your CPU, until it is complete, then the next task you receive will be an 8-thread task.

Over at PrimeGrid you are correct that many Intel CPUs have a clear advantage over Ryzen and that is predominantly related to the AVX portion of the CPU. Intel CPUs have a 256-bit width for the AVX processing and 1st and 2nd generation Ryzen CPUs only have 128-bit width. The 3rd generation Ryzen CPUs have 256-bits though, so they are comparable with most Intel CPUs (well; except for the high end Intel CPUs which have AVX512 support, which are in a league of their own for the LLR tasks). Thankfully, this does not affect the processing speed here at Amicable Numbers :D

Hope this helps! Enjoy crunching! :)

Regards,
Kellen

Hi wolfman1360!

And welcome to Amicable Numbers! Unfortunately for your new GTX 1080 GPU workunits are extremely inefficient at the moment as the vast majority (99%+) of the calculations performed for each workunit are done by the CPU. This will change in a month or two when we finish searching up to 10^20 and begin the search up to 10^21. Until that time it is still possible to run GPU workunits, however you will not be able to fully utilize the GTX 1080 even with a very powerful CPU and as many workunits as you have threads on that CPU. Instead; you can run the CPU version of the program here and it has an excellent credit/day throughput compared to almost any other project.

If you would like to participate in Amicable Numbers to help finish the search to 10^20 faster and get to those GPU-efficient 10^21 workunits faster my recommendation would be to run CPU workunits here, and then put the GPU power towards something like Collatz or the AP27 or GFN-21/22 workunits over at PrimeGrid. Those use very little CPU to run efficiently on a GTX 1080. Then, once we begin the search to 10^21, switch the GTX 1080 over to here and watch the credits pile in :)

Regards,
Kellen