Date: Fri, 30 Oct 1998 15:37:02 -0700 (MST) From: David G Andersen <danderse@cs.utah.edu> To: hackers@FreeBSD.ORG Cc: sclawson@cs.utah.edu, danderse@cs.utah.edu, mike@fast.cs.utah.edu Subject: nfs/amd hangs / getattr request flood problem Message-ID: <199810302237.PAA01262@lal.cs.utah.edu>
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We're in the process of configuring some new machines (for personal and
distributed build farm use), and we're seeing some atrocities with amd.
The machines are running 3.0-RELEASE (plus the last few days of checked in
fixes). They receive AMD maps via NIS and a static map, but disabling NIS
doesn't affect things. We've made significant tweaks to the rest of the
system configuration (disabling nis, mfs, slowing things down, etc) and
tried it on multiple systems, and the problem keeps popping up. This
behavior isn't exhibited in 2.2.x.
We have AMD looking at /n/{machine}/path, with the actual mounts on
/a/{machine}. When compiling with a source tree on /n/machine/path and an
object tree on local /z, AMD can use up to 50% of the processor. Ktrace
and tcpdump output shows that it's handling around 150 getattr requests
per second, on "/n" and "/n/machine", and the ktrace indicates that that's
the _only_ thing it's doing.
The result of this is some serious slowdowns, and reproducible system
freezes (kernel alive and pingable, no userland activity whatsoever).
Unfortunately, we don't have a simple way of reproducing the hangs yet -
it happens while running the Linux suse Matrox Xserver and the FreeBSD
netscape (entering, then leaving, and then re-entering Netscape frequently
triggers the hang).
There don't seem to be any references to this in gnats or on the lists.
We're working on forward-porting the 2.2.x amd to 3.0 to see if the
behavior still exists, but in the meantime, if anyone has suggestions /
thoughts / knows what's wrong and wants to clue me in, it'd be greatly
appreciated. :)
-Dave
--
work: danderse@cs.utah.edu me: angio@pobox.com
University of Utah http://www.angio.net/
Department of Computer Science
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