Re: [PATCH] 2.2.17pre7 VM enhancement Re: I/O performance on

[Marcelo Tosatti]

On Wed, 28 Jun 2000, Andrea Arcangeli wrote:

> On Wed, 28 Jun 2000, Marcelo Tosatti wrote:
> 
> >The problems were not fix by the protected-balance, but by returning
> >success on any progress made at do_try_to_free_pages().
> 
> Returning success on any progress makes a difference only during oom (and	
> it also caused my machine to hang and I had to use SYSRQ+E). If you aren't
> oom then it doesn't change anything.
> 
> >Alan is going to apply them together anyway, thats why I merged them. 
> 
> Alan prefers to get them separately AFIK, otherwise I would not keeping
> them separately in first place ;).

Alan, 

The balance dirty state patch from Andrea against 2.2.17pre9 is located at
http://bazar.conectiva.com.br/~marcelo/patches/v2.2/2.2.17pre9/balance-dirty-andrea.patch. 

As Andrea noted, with 2.2.17pre9 a process may wait for IO completion of a
dirty buffer while there are freeable pages in memory.  To fix that, I've
changed try_to_free_buffers to wait on dirty buffers only if:

 - do_try_to_free_pages scanning priority is <= 1, meaning that we already
scanned a big amount of pages and still have not found the needed amount
of freeable pages.

or
 
- the VM is very dirty. 

This patch, against 2.2.17pre9+balance-dirty-andrea.patch is located at 
http://bazar.conectiva.com.br/~marcelo/patches/v2.2/2.2.17pre9/wait-dirty.patch