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 from this list: send the line "unsubscribe linux-api" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
