Re: Hard-limits for kern.maxproc
Re: Hard-limits for kern.maxproc
- Subject: Re: Hard-limits for kern.maxproc
- From: Nathan <email@hidden>
- Date: Thu, 5 Feb 2009 11:51:01 -0700
On Thu, Jan 29, 2009 at 7:36 PM, Terry Lambert <email@hidden> wrote:
> On Jan 29, 2009, at 11:15 AM, Nathan <email@hidden> wrote:
>>
>> After a frustrating and long search for the root of the various
>> problems I was having with my new Xserve serving email via IMAP, I was
>> tipped off by...
>>
>> http://support.apple.com/kb/TS1659
>>
>> ...that the kernel has insanely low defaults (for a server) for
>> kern.maxproc (532), which controls the maximum amount of processes
>> allowed to run on the system. While trying to raise the default to a
>> reasonable value (Linux defaults to 32,768 for example), I discovered
>> that I couldn't raise it above 2500. Peter O'Gorman tells me off that
>> this is a hard-coded limit in Xnu:
>>
>> ./bsd/conf/param.c:#define HNPROC 2500 /* based on thread_max */
>>
>> I've already filed rdar://6536876 asking that this be raised, but as
>> I've had very poor returns with my filed bugs that I spent a long time
>> researching, and very good returns on Apple mailing lists (go
>> apple-x11!), I thought I'd post here too. :-)
>>
>> Is there any reason the hard limit couldn't be raised an order of
>> magnitude or two?
>
> Yes. Fragility under resource starvation conditions. This has already been
> asked and answered in this mailing list previously (search the archives for
> "resource limits"), but the tuning values you specify for a general purpose
> system have to be lower than those for a role based system, since a general
> system has to be able to handle all the resources if every type being
> consumed. Role based systems use a set of resources whose type is
> constrained by the role. In trade for tuning down (or simply not using), and
> administrator may safely tune up the resources used in that role, making the
> system a better fit for the role.
Terry, I understand the intent you are trying to express (the default
settings need to work well for the general case) but I disagree with
your assertion that having such extremely low limits (max processes in
particular, but I suspect other settings as well) serves that goal.
I'm running out of political and motivational steam to pursue this
issue, as I've worked around the most pressing problems we were
experiencing internally. I've canceled most of our plans regarding
the Xserve and OS X server, as I no longer have any confidence in
Apple's ability to deliver on their marketed server features or
capacity. The problem seems to run deeper than just bugs.
I will continue to keep an eye out for shifts in the landscape for OS
X server. I hope to be proven wrong in the future, and find that OS X
Server delivers on its promises.
~ Nathan
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