On Tue, 21 Sep 2010 23:10:08 +0100 Mel Gorman <mel@xxxxxxxxx> wrote: > On Tue, Sep 21, 2010 at 02:44:13PM -0700, Andrew Morton wrote: > > On Mon, 20 Sep 2010 10:52:39 +0100 > > Mel Gorman <mel@xxxxxxxxx> wrote: > > > > > > > This patch tracks how many pages backed by a congested BDI were found during > > > > > scanning. If all the dirty pages encountered on a list isolated from the > > > > > LRU belong to a congested BDI, the zone is marked congested until the zone > > > > > reaches the high watermark. > > > > > > > > High watermark, or low watermark? > > > > > > > > > > High watermark. The check is made by kswapd. > > > > > > > The terms are rather ambiguous so let's avoid them. Maybe "full" > > > > watermark and "empty"? > > > > > > > > > > Unfortunately they are ambiguous to me. I know what the high watermark > > > is but not what the full or empty watermarks are. > > > > Really. So what's the "high" watermark? > > The high watermark is the point where kswapd goes back to sleep because > enough pages have been reclaimed. It's a proxy measure for memory pressure. > > > From the above text I'm > > thinking that you mean the high watermark is when the queue has a small > > number of requests and the low watermark is when the queue has a large > > number of requests. > > > > I was expecting "zone reaches the high watermark" was the clue that I was > talking about zone watermarks and not an IO queue but it could be better. It was more a rant about general terminology rather than one specific case. > I will try and clarify. How about this as a replacement paragraph? Works for me, thanks. -- 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>