On Thu, Aug 05, 2010 at 04:52:15PM +0200, Hannes Reinecke wrote: > I still think that implementing ordered tags is the correct way of > doing things, implementation details notwithstanding. > > It looks better conceptually than using FUA, and would be easier > from the request-queue side of things. Sorry, but ordered tags are in no way a replacement for the FUA bit. Admittedly the current barrier semantics are confusing because they mix up to only minimally related things: a) cache flushing b) ordering a) is what we really need from the filesystems point of view. b) is something all our filesystems can do ourself. We could use ordered tags to offload it, and I'd be happy if someone could prove that we're getting speedups from it, but it certainly does not replace a). With enough outstanding tags, be that using ordered tags or software managed ordering we could fill the disk enough that we don't need to write cache, but again that'll need a lot of benchmarking. -- 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
