When dirty_ratio or dirty_bytes is written the other parameter is disabled and set to 0 (in dirty_bytes_handler() / dirty_ratio_handler()). We do the same for dirty_background_ratio and dirty_background_bytes. However, in the sysctl documentation, we say that the counterpart becomes a function of the old value, that is not correct. Clarify the documentation reporting the actual behaviour. Reviewed-by: Greg Thelen <gthelen@xxxxxxxxxx> Acked-by: David Rientjes <rientjes@xxxxxxxxxx> Signed-off-by: Andrea Righi <arighi@xxxxxxxxxxx> --- Documentation/sysctl/vm.txt | 12 ++++++++---- 1 files changed, 8 insertions(+), 4 deletions(-) diff --git a/Documentation/sysctl/vm.txt b/Documentation/sysctl/vm.txt index b606c2c..30289fa 100644 --- a/Documentation/sysctl/vm.txt +++ b/Documentation/sysctl/vm.txt @@ -80,8 +80,10 @@ dirty_background_bytes Contains the amount of dirty memory at which the pdflush background writeback daemon will start writeback. -If dirty_background_bytes is written, dirty_background_ratio becomes a function -of its value (dirty_background_bytes / the amount of dirtyable system memory). +Note: dirty_background_bytes is the counterpart of dirty_background_ratio. Only +one of them may be specified at a time. When one sysctl is written it is +immediately taken into account to evaluate the dirty memory limits and the +other appears as 0 when read. ============================================================== @@ -97,8 +99,10 @@ dirty_bytes Contains the amount of dirty memory at which a process generating disk writes will itself start writeback. -If dirty_bytes is written, dirty_ratio becomes a function of its value -(dirty_bytes / the amount of dirtyable system memory). +Note: dirty_bytes is the counterpart of dirty_ratio. Only one of them may be +specified at a time. When one sysctl is written it is immediately taken into +account to evaluate the dirty memory limits and the other appears as 0 when +read. Note: the minimum value allowed for dirty_bytes is two pages (in bytes); any value lower than this limit will be ignored and the old configuration will be -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>