On 05/06/2014 09:25 AM, Peter Zijlstra wrote: > On Sun, May 04, 2014 at 08:41:09AM -0400, Rik van Riel wrote: >> Even on 8-node DL980 systems, the NUMA distance in the >> SLIT table is less than RECLAIM_DISTANCE, and we will >> do wake_affine across the entire system. > > Yeah, so the problem is that (AFAIK) ACPI doesn't actually specify a > metric for the SLIT distance. This (in as far as BIOS people would care > to stick to specs anyhow) has lead to the 'fun' situation where BIOS > engineers tweak SLIT table values to make OSes behave as they thing it > should. > > So if the BIOS engineer finds that this system should have < > RECLAIM_DISTANCE it will simply make the table such that the max SLIT > value is below that. > > And yes, I've seen this :-(
It appears to be the case on the vast majority of the NUMA systems that are actually in use. To me, this suggests that we should probably deal with it. -- All rights reversed -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
