Subject: Re: Heavy swapping causes deadlock in uvm_unlock_fpageq
To: Chuck Silvers <firstname.lastname@example.org>
From: Rick Byers <RickB@BigScaryChildren.net>
Date: 07/05/2001 11:21:28
Thanks, that makes sense. I was wondering if it could be something like
that - I've seen NetBSD behave very badly when swap is almost exhausted.
I've already added a 100 MB swap file and I'll probably throw in another
drive and setup a big swap partition just incase.
On Thu, 5 Jul 2001, Chuck Silvers wrote:
> Date: Thu, 5 Jul 2001 08:11:24 -0700
> From: Chuck Silvers <email@example.com>
> To: Rick Byers <RickB@BigScaryChildren.net>
> Cc: current-users@Netbsd.org
> Subject: Re: Heavy swapping causes deadlock in uvm_unlock_fpageq
> most likely what's happening is that you're getting really close to running
> out of swap and running into the problems with the out-of-swap detection
> in the 1.5-branch code. top showing 100 MB of swap free doesn't mean much,
> since it's entirely possible that a process allocating enough memory to
> use up that 100 MB of swap will prevent top from have the memory it needs
> to run.
> if this is the case then the only thing you can do is use less memory or
> add more swap space. I've been working on some changes to -current for
> a while now that will make it so that the system doesn't get stuck
> (instead killing a process), but this depends on other stuff that's
> only in -current and the sum is too big to backport to 1.5.
> On Thu, Jul 05, 2001 at 09:07:11AM -0400, Rick Byers wrote:
> > Hi,
> > I just started doing more memory intensive stuff (i.e. lots of swapping)
> > on my NetBSD-1.5.1/i386 machine, and have been having problems with it
> > hanging. I can still switch virtual consoles and break into the debugger,
> > but nothing else works. Here is the stack trace:
> > uvm_unlock_fpageq (+0x13)
> > uvmpd_scan_inactive
> > uvmpd_scan
> > uvm_pageout
> > start_pagedaemon
> > So it looks like there is some sort of deadlock in the paging code. I
> > left top running this last time and when it froze top wasn't indicating
> > that swap space was almost exhausted or anything (infact I think it said
> > 100 Mb free) - although there were about 6 perl processes running.
> > Anyway, so my question is - I haven't noticed anything like this on my
> > NetBSD-current/i386 machine (although it probably doesn't do as much
> > swapping), does anyone know of anything that may have been fixed in
> > -current but not -release that could cause this?
> > My -release is built from June 26 sources - I'm updating now just in case.
> > I've got a crash dump, so if there is anything I can do to help track this
> > down - let me know. It's happened twice now in the last 12 hours, so I'm
> > sure it'll happen again...
> > Thanks,
> > Rick