On Wed, 7 Dec 2016, Mel Gorman wrote: > 3.0-era kernels had better fragmentation control, higher success rates at > allocation etc. I vaguely recall that it had fewer sources of high-order > allocations but I don't remember specifics and part of that could be the > lack of THP at the time. The overhead was massive due to massive stalls > and excessive reclaim -- hours to complete some high-allocation stress > tests even if the success rate was high.
There were a couple of high order page reclaim improvements implemented at that time that were later abandoned. I think higher order pages were more available than now. SLUB was regularly able to get higher order pages.
