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Heavy IO hangs [was: Re: Debian/SPARC[64]]

Hello Mark,

On Mon, Jan 12, 2015 at 12:32:41PM +0000, Mark Cave-Ayland wrote:
> I've been spending time working on the SPARC64 emulation on QEMU and can
> confirm that the latest QEMU 2.2 release is good enough boot, install
> and run all of Debian squeeze/wheezy, NetBSD and OpenBSD in -nographic
> mode. Work on Solaris is currently a slow on-going task, although
> support could be completed sooner if interested parties wanted to
> sponsor such work.
> Now I've had a couple of personal reports of QEMU users experiencing
> hard lockups during periods of high I/O under Debian wheezy similar to
> the thread at
> http://comments.gmane.org/gmane.linux.debian.ports.sparc/16093 (QEMU
> emulation is an approximation of the Ultra 5 machine) which makes me
> believe that this could be a kernel bug.

on a Sun Enterprise 250 UP Machine I found my heavy IO issue
(dd if=dev/zero of=/dev/sd<x> hangs the machine sooner or later) fixed in the
Vanilla 3.17 Kernel - see my experiences on

But later on a scsi issue stopped me with 3.18 Kernels:

> Sadly as I struggle to reproduce this issue locally then it's almost
> impossible for me to say whether this is something that affects all
> SPARC64 kernels or just a specific hardware combination, but I'd be very
> interested to hear back as to whether you also experience any lockups
> during high I/O during your testing with more recent kernels
> (particularly virtio seems to help trigger the issue under emulation).

I never saw any output on the machines where I log the console on those
heavy IO related hangups - nor was there anything in the log files
after a reboot. With squeeze I havn't noticed lookups during long runtimes.

No lookups on Sun SMP Machines running wheezy with 3.17.x kernels so far.

Hope that helps,

Netzwerkadministration/Zentrale Dienste, Interdiziplinaeres 
Zentrum fuer wissenschaftliches Rechnen der Universitaet Heidelberg
IWR; INF 368; 69120 Heidelberg; Tel: (06221)54-8236 Fax: -5224
Email: Hermann.Lauer@iwr.uni-heidelberg.de

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