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

From: Andrew Morton
Date: Fri Mar 10 2006 - 03:53:02 EST


Arjan van de Ven <arjan@xxxxxxxxxxxxx> wrote:
>
> On Fri, 2006-03-10 at 00:23 -0800, Andrew Morton wrote:
> > Arjan van de Ven <arjan@xxxxxxxxxxxxx> 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..

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