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Date:      Thu, 16 Apr 1998 22:42:14 +0800
From:      Peter Wemm <peter@netplex.com.au>
To:        "Jordan K. Hubbard" <jkh@time.cdrom.com>
Cc:        Bruce Evans <bde@zeta.org.au>, cvs-all@FreeBSD.ORG, cvs-committers@FreeBSD.ORG, cvs-sys@FreeBSD.ORG, dyson@FreeBSD.ORG
Subject:   Re: cvs commit: src/sys/kern vfs_subr.c 
Message-ID:  <199804161442.WAA17178@spinner.netplex.com.au>
In-Reply-To: Your message of "Thu, 16 Apr 1998 06:55:58 MST." <3518.892734958@time.cdrom.com> 

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"Jordan K. Hubbard" wrote:
> > > We also lost control of the update interval.
> > 
> > Yes, but it is compile-time tweakable, so those with a desperate need to 
> > tweak it can still do so, although on a power-of-two basis.
> 
> I think it'd still be nice to have it be sysctl tweakable.  If nothing
> else, it would give you a quick and easy way of saying "Hey!  Stop
> waking up the suspended drive in my laptop, dammit!" without having
> to go recompile the kernel.

Given the present structures, it's not trivial or it'd have been done by 
now.  The problem is that there's a compiled-in power-of-two sized table 
that represents work to do in 'n' seconds.  Even if this were dynamically 
reallocated and the filesystem sync period was changeable, one would very 
quickly mess up the interleave of filesystems.

Perhaps it'd be better to just have two syncer methods.  One that does the 
interleaving, and the other that does a 'sync the whole damn universe 
every <n> seconds'.  One could switch from the gradual to the all-at-once 
method but there'd be no point going back.  softdep will not run in that 
mode (not that softdep runs well at present in freebsd anyway...).

> 					Jordan
> 

Cheers,
-Peter
--
Peter Wemm <peter@netplex.com.au>   Netplex Consulting





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