Add a paragraph to introduce the functionality and usage on vmstat_mode in sysctl/vm.txt Reported-by: Jesper Dangaard Brouer <brouer@xxxxxxxxxx> Suggested-by: Dave Hansen <dave.hansen@xxxxxxxxx> Suggested-by: Ying Huang <ying.huang@xxxxxxxxx> Signed-off-by: Kemi Wang <kemi.wang@xxxxxxxxx> --- Documentation/sysctl/vm.txt | 26 ++++++++++++++++++++++++++ 1 file changed, 26 insertions(+) diff --git a/Documentation/sysctl/vm.txt b/Documentation/sysctl/vm.txt index 9baf66a..6ab2843 100644 --- a/Documentation/sysctl/vm.txt +++ b/Documentation/sysctl/vm.txt @@ -61,6 +61,7 @@ Currently, these files are in /proc/sys/vm: - swappiness - user_reserve_kbytes - vfs_cache_pressure +- vmstat_mode - watermark_scale_factor - zone_reclaim_mode @@ -843,6 +844,31 @@ ten times more freeable objects than there are. ============================================================= +vmstat_mode + +This interface allows virtual memory statistics configurable. + +When performance becomes a bottleneck and you can tolerate some possible +tool breakage and some decreased counter precision (e.g. numa counter), you +can do: + echo [C|c]oarse > /proc/sys/vm/vmstat_mode +ignorable statistics list: +- numa counters + +When performance is not a bottleneck and you want all tooling to work, you +can do: + echo [S|s]trict > /proc/sys/vm/vmstat_mode + +We recommend automatic detection of virtual memory statistics by system, +this is also system default configuration, you can do: + echo [A|a]uto > /proc/sys/vm/vmstat_mode + +E.g. numa statistics does not affect system's decision and it is very +rarely consumed. If set vmstat_mode = auto, numa counters update is skipped +unless the counter is *read* by users at least once. + +============================================================== + watermark_scale_factor: This factor controls the aggressiveness of kswapd. It defines the -- 2.7.4 -- 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>
