Subject: Re: msdosfs performance problem
To: Chuck Silvers <>
From: Michael van Elst <>
List: tech-kern
Date: 11/30/2005 20:09:34
On Wed, Nov 30, 2005 at 08:00:20AM -0800, Chuck Silvers wrote:

Hi Chuck,

> > I guess there is no optimization done for overwriting complete pages
> > and the old data is first read from the disk before it gets overwritten.
> that's right, for over-writing existing pages of a file, we currently
> read the page in from backing store before overwriting it.

what about newly allocated pages? msdosfs still shows the same behaviour.

Could that be caused by msdofs extending files first and then "rewriting"
the new pages.

> > If that is right, how do other filesystems avoid this problem?
> they don't.

Then I should see the same behaviour for ufs, but I don't.

                                Michael van Elst
                                "A potential Snark may lurk in every tree."