Re: arcmsr & areca-1660 - strange behaviour under heavy load

From: Nikola Ciprich
Date: Tue Feb 26 2008 - 14:30:17 EST


Hi Andrew,
no, right now I have the machine in the weird state, swap is empty (3GB), and so is bigger part of RAM (~100MB free), and the gcc crashes even when trying to compile c program with empty main function. so it doesn't seem to be problem with memory exhaustion.
Hopefully the areca guys will be able to find out what is going on. But anyways, if You'll have any other idea what should I check/try, please let me know, as I have to admit that I'd really like to hunt it down myself (and yes, there is some vanity on my side here :))
thanks a lot once more
cheers
nik



On Tue, 26 Feb 2008, Andrew Morton wrote:

On Tue, 26 Feb 2008 10:35:31 +0100 (CET) Nikola Ciprich <extmaillist@xxxxxxxxxxx> wrote:

Hi

On Sun, 24 Feb 2008, Andrew Morton wrote:

Hi Andrew,
thanks a lot for reply, I'm attaching requested information.
please let me know if You need more information/testing, whatever.
I'll be glad to help.
BR
nik

Areca support doesn't seem to be very interested in the problem :-(

(cc's added)

Please get the machine into this state of memory exhaustion then take
copies of the output of the following, and send them via reply-to-all to
this email:

- cat /proc/meminfo

- cat /proc/slabinfo

- dmesg -c > /dev/null ; echo m > /proc/sysrq-trigger ; dmesg -c

Thanks.

Alas, that all looks OK to me.

You never get any out-of-memory messages, and no oom-killing messages?

Possibly what is happening here is that in this low-memory condition, some
of the driver's internal memory-allocation attempts are failing, and the
driver isn't correctly handling this. This is a rare situation which may
well not have been hit in anyone else's testing.

I expect that the Areca engineers will be able to reproduce this with a
suitably small "mem=" kernel boot option. If not, they could perhaps
investigate the kernel's fault-injection framework, which permits
simulation of page allocation failures.
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