> On Tue, 29 Jan 2008 16:49:06 +0100 > Miklos Szeredi <miklos@xxxxxxxxxx> wrote: > > > Add "max_ratio" to /sys/class/bdi. This indicates the maximum > > percentage of the global dirty threshold allocated to this bdi. > > Maybe I'm having a stupid day, but I don't understand the semantics of this > min and max at all. I've read the code, and I've read the comments (well, > I've hunted for some) and I've read the docs. > > I really don't know how anyone could use this in its current state without > doing a lot of code-reading and complex experimentation. All of which > would be unneeded if this tunable was properly documented. > > So. Please provide adequate documentation for this tunable. I'd suggest > that it be pitched at the level of a reasonably competent system operator. > It should help them understand why the tunable exists, why they might > choose to alter it, and what effects they can expect to see. Hopefully a > reaonably competent kernel developer can then understand it too. OK. I think what's missing from some docs, is a high level description of the per-bdi throttling algorithm, and how it affects writeback. Because with info, I think the min and max ratios are trivially understandable: they just override the result of the algorithm, in case it would mean too high or too low threshold. Peter, could you write something about that? Thanks, Miklos - 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
