From: Chris Mason <chris.mason@oracle.com>
To: jim owens <owens6336@gmail.com>
Cc: Andi Kleen <andi@firstfloor.org>,
linux-btrfs <linux-btrfs@vger.kernel.org>
Subject: Re: [PATCH V3 17/18] Btrfs: Full direct I/O and AIO read implementation.
Date: Tue, 23 Mar 2010 20:57:19 -0400 [thread overview]
Message-ID: <20100324005719.GF5021@think> (raw)
In-Reply-To: <4BA93530.4080303@gmail.com>
On Tue, Mar 23, 2010 at 05:40:00PM -0400, jim owens wrote:
> >
> > I know the page cache currently doesn't support that today, but
> > presumably it wouldn't be too hard to add.
>
> The only reason I did not do something like that is:
> 1) I did not want to disturb the page cache with throw-away pages.
> 2) "uncached IO" makes it even less like classic direct IO.
> 3) Writing that page cache code might not be simpler.
>
> As further argument against "uncached IO", Chris sent a very simple
> patch up to read into page cache then purge it for btrfs direct IO
> reads and it was NACKed.
Yes, but it wasn't NACKed because it was uncached IO, it was just the
mechanics of how I did it. We definitely do save some performance by
not hammering on the page cache though, so I do prefer the non-buffered
code when it is possible.
-chris
next prev parent reply other threads:[~2010-03-24 0:57 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-03-22 3:34 [PATCH V3 17/18] Btrfs: Full direct I/O and AIO read implementation jim owens
2010-03-23 5:49 ` Andi Kleen
2010-03-23 21:40 ` jim owens
2010-03-24 0:57 ` Chris Mason [this message]
2010-03-24 2:37 ` Andi Kleen
2010-03-25 3:08 ` jim owens
2010-03-25 9:41 ` Andi Kleen
2010-03-25 22:38 ` jim owens
2010-03-23 21:44 ` jim owens
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