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SubjectRe: [dm-devel] Re: [RFC][PATCH 0/10] I/O context inheritance
On Tue, Apr 22, 2008 at 7:54 AM, Jens Axboe <jens.axboe@oracle.com> wrote:
> On Tue, Apr 22 2008, Hirokazu Takahashi wrote:
> > Hi,
> >
> > Sorry, these patches are for linux-2.6.25.
> >
> > > This series of patches make the block I/O layer and the I/O schedulers
> > > be able to determine the right io_context of every I/O.
> > >
> > > The current implementation of the block I/O layer and the I/O schedulers
> > > assume that the current process is the one which issued the given I/O,
> > > then use the io_context of this process to control the I/O.
> > > But this assumption isn't quite right because several kernel threads
> > > will handle I/O requests on behalf of the processes which originated them.
> > > This often happens when you want to use device mapper modules.
> > >
> > > The patches make every bio has a pointer to an io_context, which will
> > > be set when it is allocated or cloned. So it makes it possible to find
> > > the right io_context from any bio at any place.
> > >
> > > I'm waiting for your comments.
>
> Can you give a brief summary of what you need this stuff for?
>

I am not sure if this the intended application, but I have been
looking at supporting ionice over software-raid and this series seems
like a necessary first step.

--
Dan


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