On Tue, 15 Nov 2011, Mel Gorman wrote: > Fine control is limited. If it is really needed, I would not oppose > a patch that allows the use of sync compaction via a new setting in > /sys/kernel/mm/transparent_hugepage/defrag. However, I think it is > a slippery slope to expose implementation details like this and I'm > not currently planning to implement such a patch. > This doesn't expose any implementation detail, the "defrag" tunable is supposed to limit defragmentation efforts in the VM if the hugepages aren't immediately available and simply fallback to using small pages. Given that definition, it would make sense to allow for synchronous defragmentation (i.e. sync_compaction) on the second iteration of the page allocator slowpath if set. So where's the disconnect between this proposed behavior and the definition of the tunable in Documentation/vm/transhuge.txt? -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>