RE: [RFC PATCH] Introduce generalized data temperature estimation framework

[Viacheslav Dubeyko <Slava.Dubeyko@ibm.com>]

On Tue, 2025-01-28 at 08:59 +0000, Johannes Thumshirn wrote:
> On 28.01.25 09:45, Hans Holmberg wrote:
> > > I think that Direct IO could benefit too. The question here how to account dirty
> > > memory pages and updated memory pages. Currently, I am using
> > > folio_account_dirtied() and folio_clear_dirty_for_io() to implement the
> > > calculation the temperature. As far as I can see, Direct IO requires another
> > > methods of doing this. The rest logic can be the same.
> > 
> > It's probably a good idea to cover direct IO as well then as this is
> > intended to be a generalized framework.
> 
> Especially given that most applications that really care about data 
> lifetimes, write amplification etc are heavy users of direct I/O.

I believe smartphones is really huge use-case. And LFS and GC based file
systems are used there. So, page cache based approach makes sense for such
file systems to manage data placement policy efficiently.

I like this suggestion related to Direct IO case. But it needs to elaborate
the way to proper manage dirty and updated memory pages calculation for
Direct IO case.

Thanks,
Slava.