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Date: Sun, 16 May 2004 11:45:15 -0600
From: Scott Long <scottl@freebsd.org>
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To: Dan Nelson <dnelson@allantgroup.com>
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cc: Michael Hamburg <hamburg@fas.harvard.edu>
Subject: Re: fsck in -current
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Dan Nelson wrote:
> In the last episode (May 16), Scott Long said:
> 
>>Dan Nelson wrote:
>>
>>>In the last episode (May 16), Scott Long said:
>>>
>>>
>>>>Actually, bgfsck unconditionally inserts a delay into every 8th i/o
>>>>operation to try to keep from saturating the disks.  Unfortunately
>>>>this isn't terribly sophisticated and it results in bgfsck taking
>>>>an eternity whether the system is idle, loaded, or reniced.
>>>
>>>See http://dan.allantgroup.com/FreeBSD/fsck_ffs.diff for a patch
>>>that removes the delay if it's at the minimum value, and more fairly
>>>calculates disk wait time.  This cuts bgfsck time from ~4 hours to
>>>20 minutes on my 36gb /usr.
>>
>>Looks like a reasonable fix.  Do you want it reviewed and committed?
> 
> 
> Sure.  I don't remember why I bumped up the max wait time to 2.5 sec,
> though.  That's probably too long.
> 

Maybe you were seeing effects of the syncer daemon?  It can easily
generate 2+ seconds of i/o on a flush.

Scott