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[Xen-devel] Problems with dom0 and low memory

To: xen-devel@xxxxxxxxxxxxxxxxxxxxx
Subject: [Xen-devel] Problems with dom0 and low memory
From: Jérôme Petazzoni <jp@xxxxxxxx>
Date: Tue, 07 Dec 2004 11:40:53 +0100
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I am running a Xen box where I need a lot of memory for a given domain (which runs memory-hungry java apps). I had reduced the memory of domain0 to 42000KB. It *seems* that after running OK for a while, a low memory condition on domain0 messed during a short time the VBD of the other domains, and they got a burst if I/O errors. After this event, the other domains were still running, and their VBD were still working, but the burst of I/O errors aborted the ext3 journal on the filesystems (causing them to go read-only).

Here are the kernel logs of both domains if you want to check that it's indeed a low memory condition problem and not something else (which would then be a "real" bug).

I increased the memory allocated to domain0, but it would be interesting to know if there is a way to avoid those problems (I thought about increasing /proc/sys/vm/min_free_kbytes ; would it be useful here?)

The dom0 and domU kernels, as well as xen itself, the associated symbols, and the same log files are located here, if someone needs them:
http://skaya.enix.org/webs/xen/dom0-lowmem/

Attachment: dom0-kern.log.gz
Description: application/gzip

Attachment: domU-kern.log.gz
Description: application/gzip

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