Re: [RFC][WIP] DIO simplification and AIO-DIO stability

[Suparna Bhattacharya <suparna@in.ibm.com>]

On Thu, Feb 23, 2006 at 05:13:36PM -0800, Andrew Morton wrote:
> Badari Pulavarty <pbadari@us.ibm.com> wrote:
> >
> > I am still trying to understand the whole proposal to give you better
> >  feedback. But, my gut feeling is - its not going to be any more simpler
> >  than what we have today :(
> > 
> 
> Yes, that's my general reaction as well.  That code's solving a complex and
> messy problem, so it got complex and messy.

True. As you say, we just understand extent of the problem better now.
I think Stephen put in considerable thought into the implementation for
2.4, but at that time he probably didn't have to contend with the
locking modes and AIO, which have exposed a lot more scenarios, especially
with regard to error handling.

> 
> Of course, a reimplementation might certainly end up faster, cleaner,
> better.  A throw-away-and-reimplement exercise often has that result, but
> mainly because on the second time the reimplementors understand the full
> scope of the problem at the outset rather than at the end.  So this time
> around, as you imply, we'd need to get a full problem description and set
> of testcases collected.
> 
> That code does a _lot_ of stuff.  Fortunately, It's basically all in
> direct-io.c and that file exports a single function.  So it's possible that
> a reimplmentation could tick along alongside the existing implementation and
> ideally, it's just a matter of changing one entry in each filesystem's a_ops.

Sounds like a good idea.

Regards
Suparna

> 
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-- 
Suparna Bhattacharya (suparna@in.ibm.com)
Linux Technology Center
IBM Software Lab, India