Subject: Re: system looping on I/O
To: Manuel Bouyer <firstname.lastname@example.org>
From: Jaromir Dolecek <email@example.com>
Date: 11/15/2001 19:12:27
I've seen such thing happen occasionally on i386 box too, so far
sync(8) always made the system to get out of this in a while. I've
attributed this to softdeps.
Manuel Bouyer wrote:
> for a long time (since about end of july) my sparc IPX dies under heavy I/O
> load (such as a sup -o). I/O seems blocked and the disk keep trashing.
> I suspect that the same request is sent to the disk again and again,
> maybe the VM trying to flush the same dirty page(s) to disk.
> Running processes keep running until they try a disk access.
> This is not the usual out of swap problem, there is no big process and plenty
> of free swap when this happens.
> This machine has 2 disks:
> scsibus0: waiting 2 seconds for devices to settle...
> sd1 at scsibus0 target 1 lun 0: <IMPRIMIS, 94601-15, 4614> SCSI1 0/direct fixed
> sd1: 1001 MB, 1931 cyl, 15 head, 70 sec, 512 bytes/sect x 2050995 sectors
> sd1: async, 8-bit transfers
> sd0 at scsibus0 target 3 lun 0: <CONNER, CP30200 SUN0207, 4544> SCSI2 0/direct fixed
> sd0: 203 MB, 2123 cyl, 4 head, 49 sec, 512 bytes/sect x 416108 sectors
> sd0: sync (200.0ns offset 15), 8-bit (5.000MB/s) transfers
> System is on sd0, swap and sources on sd1. sd1 is really slow, maybe this is
> what triggers the problem (race condition somewhere ?).
> Anyone else seen this ?
> Manuel Bouyer, LIP6, Universite Paris VI. Manuel.Bouyer@lip6.fr
Jaromir Dolecek <jdolecek@NetBSD.org> http://www.NetBSD.org/Ports/i386/ps2.html
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