Re: [PATCH] 2.4.x write barriers (updated for ext3)

Daniel Phillips
2002-03-04T19:07:10Z

On March 4, 2002 06:24 pm, Chris Mason wrote:
> On Monday, March 04, 2002 08:57:57 AM -0600 James Bottomley wrote:
> >> 2a) Are the filesystems asking for something impossible? Can drives
> >> really write block N and N+1, making sure to commit N to media before
> >> N+1 (including an abort on N+1 if N fails), but still keeping up a
> >> nice seek free stream of writes?
> >
> > These are the "big" issues. There's not much point doing all the work to
> > implement ordered tags, if the end result is going to be no gain in
> > performance.
>
> Right, 2a seems to be the show stopper to me. The good news is
> the existing patches are enough to benchmark the thing and see if
> any devices actually benefit. If we find enough that do, then it
> might be worth the extra driver coding required to make the code
> correct.

Waiting with breathless anticipation. And once these issues are worked out,
there's a tough one remaining: enforcing the write barrier through a virtual
volume with multiple spindles underneath with separate command queues, so
that the write barrier applies to all.

--
Daniel