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SubjectRe: [RFC PATCH] ext3 writepage() journal avoidance
Andrew Morton wrote:

>Arjan van de Ven <> wrote:
>>On Fri, 2006-03-10 at 00:23 -0800, Andrew Morton wrote:
>> > Arjan van de Ven <> 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.
I did nobh option only for writeback mode + only if PAGE_SIZE ==
blocksize case :(
I guess I could enhance it for PAGE_SIZE > blocksize case also.

Doing it for ordered mode, journal mode is hard - due to transactions &
As you suggested while ago, we need a new mode. I hate to add new modes
no one will be using it (unless we decide to make it default). Thats the
reason why
I spent little time doing nobh option for writeback mode.

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

Can be added easily. I will send out a patch for this.



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