diff options
Diffstat (limited to 'Documentation/sysctl/vm.txt')
-rw-r--r-- | Documentation/sysctl/vm.txt | 17 |
1 files changed, 9 insertions, 8 deletions
diff --git a/Documentation/sysctl/vm.txt b/Documentation/sysctl/vm.txt index dd9d0e33b443..5b6da0fb5fbf 100644 --- a/Documentation/sysctl/vm.txt +++ b/Documentation/sysctl/vm.txt | |||
@@ -772,16 +772,17 @@ This is value ORed together of | |||
772 | 2 = Zone reclaim writes dirty pages out | 772 | 2 = Zone reclaim writes dirty pages out |
773 | 4 = Zone reclaim swaps pages | 773 | 4 = Zone reclaim swaps pages |
774 | 774 | ||
775 | zone_reclaim_mode is set during bootup to 1 if it is determined that pages | 775 | zone_reclaim_mode is disabled by default. For file servers or workloads |
776 | from remote zones will cause a measurable performance reduction. The | 776 | that benefit from having their data cached, zone_reclaim_mode should be |
777 | page allocator will then reclaim easily reusable pages (those page | 777 | left disabled as the caching effect is likely to be more important than |
778 | cache pages that are currently not used) before allocating off node pages. | ||
779 | |||
780 | It may be beneficial to switch off zone reclaim if the system is | ||
781 | used for a file server and all of memory should be used for caching files | ||
782 | from disk. In that case the caching effect is more important than | ||
783 | data locality. | 778 | data locality. |
784 | 779 | ||
780 | zone_reclaim may be enabled if it's known that the workload is partitioned | ||
781 | such that each partition fits within a NUMA node and that accessing remote | ||
782 | memory would cause a measurable performance reduction. The page allocator | ||
783 | will then reclaim easily reusable pages (those page cache pages that are | ||
784 | currently not used) before allocating off node pages. | ||
785 | |||
785 | Allowing zone reclaim to write out pages stops processes that are | 786 | Allowing zone reclaim to write out pages stops processes that are |
786 | writing large amounts of data from dirtying pages on other nodes. Zone | 787 | writing large amounts of data from dirtying pages on other nodes. Zone |
787 | reclaim will write out dirty pages if a zone fills up and so effectively | 788 | reclaim will write out dirty pages if a zone fills up and so effectively |