On Mon, Feb 10, 2025 at 04:39:41PM -0800, Andrew Morton wrote: > On Mon, 10 Feb 2025 00:36:16 -0500 Gregory Price <gourry@xxxxxxxxxx> wrote: > > > On Fri, Feb 07, 2025 at 06:20:09PM -0800, Andrew Morton wrote: > > > On Fri, 7 Feb 2025 12:13:35 -0800 Joshua Hahn <joshua.hahnjy@xxxxxxxxx> wrote: > > > > > > Leading to... how do we know that this patch makes the kernel better? > > > > Just focusing on this question: > > > > The default behavior of weighted interleave without this patch is > > equivalent to normal interleave. This provides a differentiation > > out-of-the box, and that's just a better experience. > > > > We may find the default values / calculations need tweaking in the > > future, but this gives us a good starting point. Anecdotally, I've > > seen an "optimal" distribution of 10:1 based on the numbers run > > sub-optimally compared to 7:1 or 13:1 (but better than default mempol). > > How was this optimality measured/observed? > TL;DR: We used MLC to observe highest sustained bandwidth. Unfortunately I can't post exact numbers at this time. To simplify the results - HMAT reported bandwidth often drifted +/- 10% compared to real observed bandwidth. So the distributions produced by auto-configuration were mildly off - but not by enough to cause performance degredation, we still saw higher sustained bandwidth. When testing the manual configurations I saw that changing from the auto-selected values to a few ticks in one direction or the other resulted in *slightly* better results. Not too surprising. So as long has hardware doesn't lie horrifically, which might be a tall ask, auto config has a good shot at giving a decent default. ~Gregory
