On Sat, Apr 25 2009, Theodore Tso wrote: > On Fri, Apr 24, 2009 at 08:40:47PM +0200, Christoph Hellwig wrote: > > On Thu, Apr 23, 2009 at 09:21:24PM +0200, Jens Axboe wrote: > > > The intent was to add some sort of notification mechanism from the file > > > system to inform the IO scheduler (and others?) that this process is how > > > holding a file system wide resource. So if you have a low priority > > > process getting access to such a resource, you want to boost its > > > priority to avoid higher priority apps getting stuck beind it. Sort of a > > > poor mans priority inheritance. > > > > > > It would be wonderful if you could kick this process more into gear on > > > the fs side... > > I have to agree with Christoph; it would be nice if this were actually > documented somewhere. Filesystem authors can't do something if they > don't understand what the semantics are and how it is supposed to be > used! I don't disagree, the project (unfortunately) never really went anywhere. THe half-assed implementation was meant to be picked up by fs people. I guess that's what is happening now, so it's a belated success :-) > I'm kind of curious why you implemented things in this way, though. > Is there a reason why the bosting is happening deep in the guts of the > cfq code, instead of in blk-core.c when the submission of the block > I/O request is processed? You would need to implement a lot more logic in the block layer to handle it there, as it stands it's basically a scheduler decision. So the positioning is right imho, the placement of fs hooks is probably mostly crap and could do with some work. -- Jens Axboe -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
