On 24 May 2025, at 20:48, Rob Landers <rob@bottled.codes> wrote:
>
> On Sat, May 24, 2025, at 19:37, Daniel Kesselberg wrote:
>>
>>
>> Hi everyone,
>>
>> I'm happy to share my first RFC :) It proposes adding a small function
>> to retrieve the number of available processors; a feature that's
>> commonly found in other programming languages and one that I believe
>> would be a useful addition to PHP.
>>
>> The related PR has already received a bit of early traction, and now
>> that the RFC is complete, I'm looking forward to your feedback!
>>
>> RFC: https://wiki.php.net/RFC/num_available_processors
>> Patch: https://github.com/php/php-src/pull/11137
>>
>> Best
>> Daniel
>>
>
> Looks good!
>
> My main question is: what is this actually counting? In the RFC it mentions
> "available processing units" ... which means, what? What counts as a
> "processing unit"? Are we talking about CPU Threads/cores; NPU cores; TPM
> cores; clocks? GPS? GPU? ... a modern computer has many "processing units"
> for different purposes and workloads. I’m assuming this is CPU Threads, not
> physical cores? I will refer to CPU Threads as "Logical Cores" so we all
> don’t get confused since most of us here are programmers and saying "thread"
> has a different meaning.
>
> Secondly, how is it counting "available"? If I assign PHP to a specific CPU
> affinity mask (say one logical core), will it return 1, or the total number
> of logical cores available on my machine? I would expect it to be 1, since
> PHP only has access to 1, but I can also see the logic in returning the total
> number.
>
> — Rob
Hi Daniel,
I agree with Rob that "processor" is a bit too ambiguous. I'd use the phrase
"cpu_core" instead. Yes, technically that's not entirely accurate when
hyper-threading is used, but in most cases it's not trivial to distinguish
physical cores from logical cores anyway, and "cpu_cores" provides the most
understandable abstraction for the vast majority of use cases: deciding how
many parallel processes one should use for optimal use of the CPU.
Also, is it really necessary to add "available" as a disambiguator? In other
words: are there future plans to add a function that provides the "total" or
"unavailable" number of processors? If not, I'd just drop the "available" part.
Finally, from a quick search in php-src there doesn't seem to be any existing
function name that starts with `num_`. For the sake of consistency with the
existing PHP functions, and similar functionality in other languages, I suggest
suffixing the function name with `_count` instead.
So, to wrap this all up, I'd like to respectfully propose the following
function name instead:
cpu_core_count()
Alwin
