On 11/23/2015 04:16 PM, Joonsoo Kim wrote:
Numbers looks fine to me. I guess this performance degradation is
caused by COMPACT_CLUSTER_MAX change (from 32 to 256). THP allocation
is async so should be aborted quickly. But, after isolating 256
migratable pages, it can't be aborted and will finish 256 pages
migration (at least, current implementation).
Aaron, please test again with setting COMPACT_CLUSTER_MAX to 32
This is what I found in include/linux/swap.h:
#define SWAP_CLUSTER_MAX 32UL
#define COMPACT_CLUSTER_MAX SWAP_CLUSTER_MAX
Looks like it is already 32, or am I looking at the wrong place?
BTW, I'm using v4.3 for all these tests, and I just checked v4.4-rc2,
the above definition doesn't change.
And, please attach always-always's vmstat numbers, too.
Sure, attached the vmstat tool output, taken every second.