Re: [PATCH 00/23] per device dirty throttling -v8

Martin Bligh
2007-08-09T00:55:14Z

Andrew Morton wrote:
> On Wed, 08 Aug 2007 14:10:15 -0700
> "Martin J. Bligh" <mbligh@mbligh.org> wrote:
>
>> Why isn't this easily fixable by just adding an additional dirty
>> flag that says atime has changed? Then we only cause a write
>> when we remove the inode from the inode cache, if only atime
>> is updated.
>
> I think that could be made to work, and it would fix the performance
> issue.
>
> It is a behaviour change. At present ext3 (for example) commits everything
> every five seconds. After a change like this, a crash+recovery could cause
> a file's atime to go backwards by an arbitrarily large time interval - it
> could easily be months.

A second pdflush / workqueue at a slower rate would alleviate that.

Yes, it's a semantic change ... but only in an incredibly small
corner-case ?