zfs process hang on pool access

[Steven Hartland]

----- Original Message ----- 
From: "Andriy Gapon" <avg at FreeBSD.org>
To: "Steven Hartland" <killing at multiplay.co.uk>
Cc: <freebsd-fs at FreeBSD.org>
Sent: Wednesday, July 27, 2011 3:10 PM
Subject: Re: zfs process hang on pool access


> on 27/07/2011 16:55 Steven Hartland said the following:
>> Apparently it seems to affect machines
>> with high uptimes, if thats of help. This machine shows:-
>> 
>> uptime
>> 1:55PM  up 112 days,  3:19, 1 user, load averages: 0.00, 0.00, 0.00
> 
> Just a guess, perhaps it's another manifestation of this issue:
> http://lists.freebsd.org/pipermail/freebsd-fs/2011-May/011584.html

Not sure looking at that thread and comparing to the machine:-

top -SHb 500 | grep arc
    7 root      -8    -     0K    88K arc_re  0  11:07  0.00% {arc_reclaim_thre}
    7 root      -8    -     0K    88K l2arc_  2   0:52  0.00% {l2arc_feed_threa}

So no excessive cpu for reclaim is present and evict_skip is not
incrementing:

sysctl kstat.zfs.misc.arcstats.evict_skip
kstat.zfs.misc.arcstats.evict_skip: 235572240
sleep 60
sysctl kstat.zfs.misc.arcstats.evict_skip
kstat.zfs.misc.arcstats.evict_skip: 235572240

    Regards
    Steve

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