Re: (reiserfs) Re: RFC: Re: journal ports for 2.3?

[Hans Reiser <reiser@idiom.com>]

"Benjamin C.R. LaHaise" wrote:

> I completly agree to change mark_buffer_dirty() to call balance_dirty()

> > before returning. But if you add the balance_dirty() calls all over the
> > right places all should be _just_ fine as far I can tell.
>
> I don't agree, both for the reasons above and because doing a
> balance_dirty in mark_buffer_dirty tends to result in stalls in the
> *wrong* place, because it tends to stall in the middle of an operation,
> not before it has begun.  You end up stalling on metadata operations that
> shouldn't stall.  The stall thresholds for data vs metadata have to be
> different in order to make the system 'feel' right.  This is easily
> accomplished by trying to "allocate" the dirty buffers before you actually
> dirty them (by checking if there's enough slack in the dirty buffer
> margins before doing the operation).
>
>                 -ben

If reiserfs had good SMP, you could stall it anywhere, and the code could handle
that.  But we don't, and I bet others also don't, and we won't have it for some
time even though we are working on it.

Hans

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