Messages in this thread | | | Date | Wed, 20 May 2009 11:47:39 +0100 | From | Mel Gorman <> | Subject | Re: [PATCH 1/3] clean up setup_per_zone_pages_min |
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On Wed, May 20, 2009 at 07:30:45PM +0900, Minchan Kim wrote: > On Wed, 20 May 2009 11:21:29 +0100 > Mel Gorman <mel@csn.ul.ie> wrote: > > > On Wed, May 20, 2009 at 06:58:03PM +0900, Minchan Kim wrote: > > > Hi, Mel. > > > > > > On Wed, 20 May 2009 09:54:16 +0100 > > > Mel Gorman <mel@csn.ul.ie> wrote: > > > > > > > On Wed, May 20, 2009 at 04:18:53PM +0900, Minchan Kim wrote: > > > > > > > > > > Mel changed zone->pages_[high/low/min] with zone->watermark array. > > > > > So, setup_per_zone_pages_min also have to be changed. > > > > > > > > > > > > > Just to be clear, this is a function renaming to match the new zone > > > > field name, not something I missed. As the function changes min, low and > > > > max, a better name might have been setup_per_zone_watermarks but whether > > > > > > At first, I thouht, too. But It's handle of min_free_kbytes. > > > Documentation said, it's to compute a watermark[WMARK_MIN]. > > > I think many people already used that knob to contorl pages_min to keep the > > > low pages. > > > > Which documentation? > > Documentation/sysctl/vm.txt - min_free_kbytes. >
That documentation states
==== This is used to force the Linux VM to keep a minimum number of kilobytes free. The VM uses this number to compute a pages_min value for each lowmem zone in the system. Each lowmem zone gets a number of reserved free pages based proportionally on its size. ====
This is true. It just happens in the implementation that sets pages_min (or it's renamed value) also sets the low and high watermarks are also set based on the value of the minimum value. It doesn't need to be updated.
> > I'm looking at the function comment and see > > > > * setup_per_zone_pages_min - called when min_free_kbytes changes. > > * > > * Ensures that the pages_{min,low,high} values for each zone are set > > * correctly with respect to min_free_kbytes. > > > > So, the values of all the watermarks are updated by that function depending > > on what the new value of min_free_kbytes is. It is a bit wrong I suppose as > > it missed memory hot-add > > > > setup_per_zone_pages_min - called when min_free_kbytes changes or when memory is hot-added > > God!. I changed this function's comments with memory hot plug. > With my mistake, My patch 3/3 lost it. > I will add comment about memory hotplug. > > Thanks for pointing me out. :) > > > > > > > > So, I determined function name is proper now. > > > If setup_per_zone_watermark is better than it, we also have to change with > > > documentation. > > > > > > > you go with that name or not, this is better than what is there so; > > > > > > > > Acked-by: Mel Gorman <mel@csn.ul.ie> > > > > > > > > > -- > > > Kinds Regards > > > Minchan Kim > > > > > > > -- > > Mel Gorman > > Part-time Phd Student Linux Technology Center > > University of Limerick IBM Dublin Software Lab > > > -- > Kinds Regards > Minchan Kim >
-- Mel Gorman Part-time Phd Student Linux Technology Center University of Limerick IBM Dublin Software Lab
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