NetBSD Problem Report #46952
From dholland@macaran.localdomain Fri Sep 14 02:47:38 2012
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Date: Thu, 13 Sep 2012 22:47:43 -0400 (EDT)
From: dholland@eecs.harvard.edu
Reply-To: dholland@eecs.harvard.edu
To: gnats-bugs@gnats.NetBSD.org
Subject: VM page allocation is borked
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>Number: 46952
>Category: kern
>Synopsis: VM page allocation is borked
>Confidential: no
>Severity: serious
>Priority: high
>Responsible: kern-bug-people
>State: open
>Class: sw-bug
>Submitter-Id: net
>Arrival-Date: Fri Sep 14 02:50:00 +0000 2012
>Originator: David A. Holland
>Release: NetBSD 6.99.11 (20120906)
>Organization:
>Environment:
System: NetBSD macaran 6.99.11 NetBSD 6.99.11 (MACARAN) #13: Thu Sep 6 20:22:11 EDT 2012 root@macaran:/usr/src/sys/arch/amd64/compile/MACARAN amd64
Architecture: x86_64
Machine: amd64
>Description:
I am running three concurrent copies of a simulation process, each
consuming about 1.5G, and even though I have 6G of RAM it is swapping
to death.
On tls's suggestion I tried raising vm.anonmax from 80 to 95; this
helped a lot. Lowering vm.execmin and vm.filemin to 3 helped a bit
more. However, even with these measures the system continued swapping;
just not as hard.
This workload should be fitting in memory. (And while I have an X
server and a browser running, they should be, and AFAICT are, mostly
paged out; in any event I'm 2G into swap.)
This may be a regression, as the reason I chose to run this thing in
batches of three is that prior experience, some a few months ago with
6.99.3 and more a bit further back using 5.99.59, was that three
copies would fit in memory without swapping but four wouldn't.
There seem to be two problems here: one that a workload using 75% of
installed RAM swaps, and one that the VM tuning is making it quite a
bit worse.
>How-To-Repeat:
Run a few processes with large working sets.
>Fix:
fiik.
(Contact us)
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