Re: [PATCH 3/3] kernel/sysctl.c: threads-max observe limits

Heinrich Schuchardt
2015-02-25T18:49:20Z

On 24.02.2015 23:20, David Rientjes wrote:
> On Tue, 24 Feb 2015, Heinrich Schuchardt wrote:
>
>>>> Users can change the maximum number of threads by writing to
>>>> /proc/sys/kernel/threads-max.
>>>>
>>>> With the patch the value entered is checked against the same
>>>> limits that apply when fork_init is called.
>>>>
>>>
>>> Correct me if I'm wrong, but this is a change in functionality (without
>>> update to Documentation/sysctl/kernel.txt which describes threads-max)
>>> since it does not allow the value to be lowered as before from the
>>> calculation involving totalram_pages. The value passed to
>>> set_max_threads() only caps the value.
>>
>> threads_max is set to the value the user inputs if it is inside the
>> interval [20, FUTEX_TID_MASK] and it is capped by the value calculated
>> from totalram_pages.
>>
>> So lowering and raising is still possible (inside the limits).
>>
>
> I believe this information should be added to the documentation cited
> above which mentions threads-max since users will otherwise be unfamiliar
> with the limits imposed.

Hello David,

I guess the documentation fix should be put into a separate patch (of
the same patch series) as Jonathan Corbet uses a separate git tree to
consolidate documentation changes. Is that ok with you?

Best regards

Heinrich