On Fri, 20 Mar 2015 09:49:50 -0400 Eric B Munson <emunson@xxxxxxxxxx> wrote: > Currently, pages which are marked as unevictable are protected from > compaction, but not from other types of migration. The POSIX real time > extension explicitly states that mlock() will prevent a major page > fault, but the spirit of this is that mlock() should give a process the > ability to control sources of latency, including minor page faults. > However, the mlock manpage only explicitly says that a locked page will > not be written to swap and this can cause some confusion. The > compaction code today does not give a developer who wants to avoid swap > but wants to have large contiguous areas available any method to achieve > this state. This patch introduces a sysctl for controlling compaction > behavior with respect to the unevictable lru. Users that demand no page > faults after a page is present can set compact_unevictable_allowed to 0 > and users who need the large contiguous areas can enable compaction on > locked memory by leaving the default value of 1. Do we really really really need the /proc knob? We're already migrating these pages so users of mlock will occasionally see some latency - how likely is it that this patch will significantly damage anyone? -- 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>