Re: [9fans] Maximal number of processes

[Steven Stallion <sstallion@gmail.com>]

On Wed, Jan 8, 2014 at 2:28 AM, Pavel Klinkovský
<pavel.klinkovsky@gmail.com> wrote:
> Hi all,
>
> I would like to know whether there is any hard (based on CPU architecture)
> limit of maximal number of processes in Plan9 on Intel or ARM.
>
> I do not think the soft limit like the lack of memory... ;)
>
> Thanks in advance for any hint.

Hi Pavel,

It absolutely does. Depending on the kernel you are booting,
conf.nproc will be set in a variety of different ways. This is
generally set in confinit, called from main. The obvious example is
the pc kernel:

    conf.nproc = 100 + ((conf.npage*BY2PG)/MB)*5;
    if(cpuserver)
            conf.nproc *= 3;
    if(conf.nproc > 2000)
            conf.nproc = 2000;

In general, you will find that 2000 is the highest allowable due to
limits imposed by proc.c. Other architectures can (and will) place
additional restrictions. A non-FCSE ARM implementation could elect to
only support 256 processes to avoid additional switching overhead for
example.

At the end of the day, the only way to be sure is to read the source.
It will give you a better familiarity with the system and probably
avoid some unnecessary perturbation.

Cheers,

Steve