On Tue, Feb 23, 2016 at 03:04:23PM +0000, Mel Gorman wrote: > In many benchmarks, there is an obvious difference in the number of > allocations from each zone as the fair zone allocation policy is removed > towards the end of the series. For example, this is the allocation stats > when running blogbench that showed no difference in headling performance > > mmotm-20160209 nodelru-v2 > DMA allocs 0 0 > DMA32 allocs 7218763 608067 > Normal allocs 12701806 18821286 > Movable allocs 0 0 According to the mmotm numbers, your DMA32 zone is over a third of available memory, yet in the nodelru-v2 kernel sees only 3% of the allocations. That's an insanely high level of aging inversion, where the lifetime of a cache entry is again highly dependent on placement. The fact that this doesn't make a performance difference in the specific benchmarks you ran only proves just that: these specific benchmarks don't care. IMO, benchmarking is not enough here. If this is truly supposed to be unproblematic, then I think we need a reasoned explanation. I can't imagine how it possibly could be, though. If reclaim can't guarantee a balanced zone utilization then the allocator has to keep doing it. :( As far as I'm concerned, the original reason for the fair zone allocator still applies. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>