Jamie Lokier wrote: > Christoph Hellwig wrote: > > On Tue, Sep 01, 2009 at 08:38:55PM +0200, Peter Zijlstra wrote: > > > Do we really need a tunable for this? > > > > It will make increasing it in the field a lot easier. And having deal > > with really large systems I have the fear that there are I/O topologies > > outhere for which every "reasonable" value is too low. > > > > > I guess we need a limit to avoid it writing out everything, but can't we > > > have something automagic? > > > > Some automatic adjustment would be nice. But finding the right auto > > tuning will be an interesting exercise. > > I have embedded systems with 32MB RAM and no MMU, where I deliberately > make the equivalent of max_writeback_pages *smaller* to limit the > number of dirty pages causing fragmentation and preventing allocation > of high-order pages... Write performance is less important than being > able to allocate contiguous memory for reads. > > They are still using 2.4 kernels, but the principle still applies. > maybe even more on 2.6 which is more prone to fragmentation on small > no-MMU devices. Sorry, I must get more sleep. I confused max_writeback_pages with the limit on dirty pages in the system, which is completely different. So please ignore my previous mail. *little*, -- Jamie -- 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
