Re: [RFC PATCH] ext3 writepage() journal avoidance

[Andrew Morton <akpm@osdl.org>]

Arjan van de Ven <arjan@infradead.org> wrote:
>
> On Fri, 2006-03-10 at 00:23 -0800, Andrew Morton wrote:
>  > Arjan van de Ven <arjan@infradead.org> wrote:
>  > >
>  > > 
>  > > > I'm not sure that PageMappedToDisk() gets set in all the right places
>  > > > though - it's mainly for the `nobh' handling and block_prepare_write()
>  > > > would need to be taught to set it.  I guess that'd be a net win, even if
>  > > > only ext3 uses it..
>  > > 
>  > > btw is nobh mature enough yet to become the default, or to just go away
>  > > entirely as option ?
>  > 
>  > I don't know how much usage it's had, sorry.  It's only allowed in
>  > data=writeback mode and not many people seem to use even that.
> 
>  would you be prepared to turn it on by default in -mm for a bit to see
>  how it holds up?

spose so.  One would have to test it a bit first, make sure that it still
works.  Performance testing with PAGE_SIZE much-greater-than blocksize
would be needed.

Unfortunately there's no `-o bh' (nonobh?) to turn it back on again if it
causes problems..