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To: Attilio Rao <attilio@freebsd.org>
From: "Poul-Henning Kamp" <phk@phk.freebsd.dk>
In-Reply-To: Your message of "Thu, 15 Apr 2010 12:10:21 +0200."
	<r2r3bbf2fe11004150310w9fa12d12vebd6b7f73cc1c5c0@mail.gmail.com> 
Date: Fri, 16 Apr 2010 08:23:03 +0000
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Cc: Giovanni Trematerra <giovanni.trematerra@gmail.com>,
	freebsd-arch@freebsd.org
Subject: Re: [PATCH] Syncer rewriting 
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In message <r2r3bbf2fe11004150310w9fa12d12vebd6b7f73cc1c5c0@mail.gmail.com>, At
tilio Rao writes:

>The syncer, meant as what we have now, becames the 'standard one' but
>switches to a different model. It becames per-mount and it then gets
>rid of the syncer vnode. This also helps in simplifying a lot the
>locking within the syncer because now any thread is responsible only
>for its own dog-food.

YeeeeEEEEEHAAAAA!

Go! Go! GO!


>- The standard syncer may be further improved getting rid of the
>bufobj. It should actually handle a list of vnodes rather than a list
>of bufobj. However similar optimizations may be done after the patch
>is ready to enter the tree.

That would be the wrong direction: we need the bufobj because for instance
a RAID5 geom module does not have a vnode for the parity data.

If you force the syncer to only work on vnodes, then we need a parallel
mechanism for non-filesystem disk users.

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.