On Fri, Aug 13, 2010 at 04:56:32PM +0400, Vladislav Bolkhovitin wrote: > Tejun Heo, on 08/12/2010 04:41 PM wrote: > >Nobody is making meaningful use of ORDERED_BY_TAG now and queue > >draining for barrier requests will be removed soon which will render > >the advantage of tag ordering moot. > > Have you seen Hannes Reinecke's and my measurements in > http://marc.info/?l=linux-scsi&m=128110662528485&w=2 and > http://marc.info/?l=linux-scsi&m=128111995217405&w=2 correspondingly? > > If yes, what else evidences do you need to see that the tag ordering is > a big performance win? It's not tag odering that is a win but big queue depth. That's what you measured and what I fully agree on. I haven't been able to get out of Hannes what he actually measured. And if you'd actually look at the patchset allowing deep queues is exactly what it allows us, and while I haven't done testing on this patchset but only on my previous version it does get us back to use the full potential of large arrays exactly because of that. -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
