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Re: Proposal: B_ARRIER (addresses wapbl performance?)

On Tue, Dec 09, 2008 at 05:17:22PM -0500, Thor Lancelot Simon wrote:
> On Mon, Dec 08, 2008 at 07:37:46PM -0800, Jason Thorpe wrote:
> >
> > On Nov 4, 2008, at 4:03 PM, Bill Stouder-Studenmund wrote:
> >
> >> My biggest concern with the tag use is that your barrier mixes in with 
> >> ALL
> >> the outstanding i/o. Even reads.
> >
> > Not just "i/o"... even commands like inquiry....
> No -- inquiries, reservations and the like are "implicit HEAD OF QUEUE"
> commands, at least as I read the standard.

I read the original as being a concern with respect to ordering within
our disksort, before it ever got to the disk interface.  Clearly, we
have some ability to address this concern, which is what makes it
useful feedback on the proposal as written.


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