On Tuesday 14 August 2007 01:46, Evgeniy Polyakov wrote: > On Mon, Aug 13, 2007 at 06:04:06AM -0700, Daniel Phillips (phillips@xxxxxxxxx) wrote: > > Perhaps you never worried about the resources that the device > > mapper mapping function allocates to handle each bio and so did not > > consider this hole significant. These resources can be > > significant, as is the case with ddsnap. It is essential to close > > that window through with the virtual device's queue limit may be > > violated. Not doing so will allow deadlock. > > This is not a bug, this is special kind of calculation - total limit > is number of physical devices multiplied by theirs limits. It was > done _on purpose_ to allow different device to have different limits > (for example in distributed storage project it is possible to have > both remote and local node in the same device, but local device > should not have _any_ limit at all, but network one should). > > Virtual device essentially has _no_ limit. And that as done on > purpose. And it will not solve the deadlock problem in general. (Maybe it works for your virtual device, but I wonder...) If the virtual device allocates memory during generic_make_request then the memory needs to be throttled. Regards, Daniel - To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
