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Date: Thu, 14 Jun 2012 12:45:13 +0200
From: Martin Matuska <mm@FreeBSD.org>
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To: Alexandr Kovalenko <alexandr.kovalenko@gmail.com>
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Cc: freebsd-fs@freebsd.org
Subject: Re: zfs list -t snapshot slow
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Hi Alexandr,

this slowdown is known, as for fetching each snapshot its metadata are
to be fetched.
There was a speedup to this operation, but it affects only name-sorted
output,
you need to issue "-o name -s name" to your zfs list command.

More information:
http://svnweb.freebsd.org/base?view=revision&revision=230438

This change has been integrated into the tree on:
HEAD: r230438 (2012-01-21)
9-STABLE: r231946 (2012-02-20)
8-STABLE: r233862 (2012-04-04)

On 14. 6. 2012 12:24, Alexandr Kovalenko wrote:
> Hello!
>
> I've noticed it takes pretty unreasonable amount of time to list snapshots:
>
> # time (zfs list -t snapshot 2>&1 > /dev/null)
>
> real    0m4.919s
> user    0m0.146s
> sys     0m0.716s
>
> # zfs list -t snapshot | wc -l
>     1838
>
> kdump -f ktrace.out attached.
>
> Could anyone please advise what could cause this problem?
-- 
Martin Matuska
FreeBSD committer
http://blog.vx.sk