On 4/16/19 8:33 AM, Zi Yan wrote: >> We have a reasonable argument that demotion is better than >> swapping. So, we could say that even if a VMA has a strict NUMA >> policy, demoting pages mapped there pages still beats swapping >> them or tossing the page cache. It's doing them a favor to >> demote them. > I just wonder whether page migration is always better than > swapping, since SSD write throughput keeps improving but page > migration throughput is still low. For example, my machine has a > SSD with 2GB/s writing throughput but the throughput of 4KB page > migration is less than 1GB/s, why do we want to use page migration > for demotion instead of swapping? Just because we observe that page migration apparently has lower throughput today doesn't mean that we should consider it a dead end.
