Date: Fri, 9 Jul 1999 23:07:23 -0700 (PDT) From: Matthew Dillon <dillon@apollo.backplane.com> To: Stephen Hocking-Senior Programmer PGS Tensor Perth <shocking@prth.pgs.com> Cc: current@FreeBSD.ORG Subject: Re: Dirty pages & low memory hangs with mmap Message-ID: <199907100607.XAA52988@apollo.backplane.com> References: <199907090340.LAA04093@ariadne.tensor.pgs.com>
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:I've been seeing an interesting problem when doing a make installworld on a
:486 with 16MB of memory. Immediately after installing libc.so.3, it will hang.
:DDB gives a backtrace to a mmap related call (sorry, the box is at home at the
:memoment and this email was prompted by something on freebsd-current). It's
:quite reproducible, but worked around by issuing a bunch of syncs every
:second. Outside of that, the box runs fine (it's my ppp NAT gateway, runs
:squid & nntpcached as well).
:
:
: Stephen
If you can run a kernel with DDB configured, you can break into DDB
after the machine hangs with ctl-alt-esc and then do a 'ps' to see what
all the processes are blocked in.
One of two known low memory hang conditions was fixed in a commit a day
or two ago.
The remaining known low memory hang occurs when files are mmap()'d shared
and pages are dirtied directly. I've been trying to track that one down
along with another hang in 'objtrm' without much luck so far.
But to figure out exactly why your machines is hanging I need the DDB
ps output.
-Matt
Matthew Dillon
<dillon@backplane.com>
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