From 32766cd281b1f7930790ce4840b8e08964ab737f Mon Sep 17 00:00:00 2001 From: Adrian Chadd Date: Thu, 10 Sep 2015 04:05:58 +0000 Subject: Also make kern.maxfilesperproc a boot time tunable. Auto-tuning threshold discussions aside, it turns out that if you want to lower this on say, rather memory-packed machines, you either set maxusers or kern.maxfiles, or you set it in sysctl. The former is a non-exact way to tune this; the latter doesn't actually affect anything in the startup scripts. This first occured because I wondered why the hell screen would take upwards of 10 seconds to spawn a new screen. I then found python doing the same thing during fork/exec of child processes - it calls close() on each FD up to the current openfiles limit. On a 1TB machine this is like, 26 million FDs per process. Ugh. So: * This allows it to be set early in /boot/loader.conf; * It can be used to work around the ridiculous situation of screen, python, etc doing a close() on potentially millions of FDs even though you only have four open. Tested: * 4GB, 32GB, 64GB, 128GB, 384GB, 1TB systems with autotune, ensuring screen and python forking doesn't result in some pretty hilariously bad behaviour. TODO: * Note that the default login.conf sets openfiles-cur to unlimited, effectively obeying kern.maxfilesperproc. Perhaps we should fix this. * .. and even if we do, we need to also ensure that daemons get a soft limit of something reasonable and capped - they can request more FDs themselves. MFC after: 1 week Sponsored by: Norse Corp, Inc. --- sys/kern/subr_param.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'sys/kern/subr_param.c') diff --git a/sys/kern/subr_param.c b/sys/kern/subr_param.c index 36608d1f52b8..52c6f167f753 100644 --- a/sys/kern/subr_param.c +++ b/sys/kern/subr_param.c @@ -265,7 +265,8 @@ init_param2(long physpages) if (maxfiles > (physpages / 4)) maxfiles = physpages / 4; maxfilesperproc = (maxfiles / 10) * 9; - + TUNABLE_INT_FETCH("kern.maxfilesperproc", &maxfilesperproc); + /* * Cannot be changed after boot. */ -- cgit v1.2.3