On Fri, Sep 12, 2008 at 1:18 PM, Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote: > One thing to think about please: Michael Rubin is hitting problems with > the existing /proc/sys/vm/dirty-ratio. Its present granularity of 1% > is just too coarse for really large machines, and as > memory-size/disk-speed ratios continue to increase, this will just get > worse. Re-sending since I top-posted before. Never again. Also adding more thoughts on a byte based interface. Currently the problem we are hitting is that we cannot specify pdflush to have background limits less than 1% of memory. I am currently finishing up a patch right now that adds a dirty_ratio_millis interface. I hope to submit the patch to LKML by the end of the week. The idea is that we don't want to break backwards compatibility and we also don't want to have two conflicting knobs in the sysctl or /proc/sys/vm/ space. I thought adding a new knob for those who want to specify finer grained functionality was a compromise. So the patch has a vm_dirty_ratio and a vm_dirty_ratio_millis interface. The first to specify 0-100% and the second to specify .0 to .999%. So to represent 0.125% of RAM we set vm_dirty_ratio = 0 vm_dirty_ratio_millis = 125 The same for the background_ratio. I would also prefer using a bytes interface but I am not sure how to offer that without either removing the legacy interface of the ratios or by offering a concurrent interface that might be confusing such as when users are looking at the old one and not aware of a new one. Any feedback? mrubin _______________________________________________ Containers mailing list Containers@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/containers