Re: [OE-core] [PATCH] rust: Enable parallel-frontend-threads

[Sundeep KOKKONDA <Sundeep.Kokkonda@windriver.com>]

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On 12-Mar-26 14:32, Alexander Kanavin wrote:
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> On Thu, 12 Mar 2026 at 05:07, Sundeep KOKKONDA via
> lists.openembedded.org
> <sundeep.kokkonda=windriver.com@lists.openembedded.org> wrote:
>> Test Results:
>> A few tests ran by, with and without enabling this option.
>> - Avg. default build time (w/o this option) - 56m 50.104s
>> - Avg. build time with this option - 49m 17.224s
>> - Performance Difference - 7m 32.880s faster builds (≈ 13.3%)
>>
>> Tests were performed by setting thread count as 8 & 16 but no much difference is seen.
>> So, the parallel-frontend-threads = 8 is set.
> It would really help to provide specifics. What tests did you run, and
> how were the numbers obtained? How can these tests be reproduced? What
> CPU was used and how many cores it had?

I tested the rust build time with `time bitbake rust` (I wonder how I 
missed this to put is commit msg)

Machine Info: Intel(R) Xeon(R) CPU E5-4669 v3 @ 2.10GHz with 144 CPUs.

>
>> +    config.set("rust", "parallel-frontend-threads", "8")
> I'd suggest we don't hardcode a number, but rather set to oe.utils.cpu_count()
> (grep oe-core for examples).

I choose 8 here as there is no noticeable difference between 8/16. Also, the rust blog says (https://blog.rust-lang.org/2023/11/09/parallel-rustc/) -

/We recommend eight threads because this is the configuration we have 
tested the most and it is known to give good results. Values lower than 
eight will see smaller benefits, but are appropriate if your hardware 
has fewer than eight cores. Values greater than eight will give 
diminishing returns and may even give worse performance. /
Thanks,
Sundeep K

>
> Alex

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