Hard-limits for kern.maxproc
Hard-limits for kern.maxproc
- Subject: Hard-limits for kern.maxproc
- From: Nathan <email@hidden>
- Date: Thu, 29 Jan 2009 12:15:48 -0700
I've been posting about this to macos-x-server and unix-porting for a
few days before it dawned on me that there was probably a kernel
mailing list. So...Hi! My name's Nathan and this is my first post.
----
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? Even with raising kern.maxproc (and
kern.maxprocperuid and the launchd settings that mirror it and
launchd's maxfiles setting, etc. etc) my Xserve will run into the
process limit far before it exhausts CPU, RAM, disk, or bandwidth
resources.
I'd be happy to provide some legwork (testing, doing some sanity
checks on stuff in the kernel source code, etc.) if that would help.
I am a registered ADC member and I'm willing to get my hands dirty to
get this fixed. I've set up four-dozen OS X stations up in my
company, as well as 200 linux stations, all of which access our Xserve
for mail. It was very embarassing when we switched from our email
hosting provider (who used OpenBSD) to our own Apple Xserve (I didn't
want to have to learn to configure courier+cyrus+postfix+whatever all
by myself on a Linux server) that we had so many problems for so long
and it took two months to narrow it down to an apparently arbitrarily
small value for kern.maxproc (and launchd).
~ Nathan
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