Re: [Bug 9941] New: Zone "Normal" missing in /proc/zoneinfo

[Mel Gorman <mel@csn.ul.ie>]

On (13/02/08 15:23), Andy Whitcroft didst pronounce:
> On Wed, Feb 13, 2008 at 11:52:25AM +0000, Mel Gorman wrote:
> 
> > > > > > $ grep zone /proc/zoneinfo
> > > > > >
> > > > > > Output with 2.6.24:
> > > > > > Node 0, zone      DMA
> > > > > > Node 0, zone    DMA32
> > > > > > Node 0, zone   Normal
> > > > > >
> > > > > > Output with 2.6.24.2:
> > > > > > Node 0, zone      DMA
> > > > > > Node 0, zone    DMA32
> > > > > >
> > 
> > The greater surprise to me is that "Normal" ever appeared. The zone is empty,
> > why is information appearing about it? I checked the dmesg for an x86_64
> > machine with 1GB of RAM that was running 2.6.24 here and there is no sign
> > of Normal.
> > 
> > mel@arnold:/tmp$ grep zone zoneinfo.before 
> > Node 0, zone      DMA
> > Node 0, zone    DMA32
> > 
> > The loop looks like
> > 
> >         for (zone = node_zones; zone - node_zones < MAX_NR_ZONES; ++zone) {
> >                 if (!populated_zone(zone))
> >                         continue;
> > 
> > It makes no sense for it to show up *unless* 2.6.24 was compiled as a 32
> > bit kernel by accident. Could this be the case?
> 
> Interestingly I would not expect to see DMA32 at all if the kernel was
> compiled 32 bit as CONFIG_DMA32 defaults to X86_64.
> 

D'oh, of course. This couldn't have been a 32 bit kernel.

> Could we simply have less ram detected/present in this boot.  That would
> make the zone dissappear if it became empty.
> 
> The e820 output as reported by the old and new kernels would confirm the
> memory size is detected the same.  Also some idea of how much memory is
> supposed be in the machine might shed some light.  If the overall is near
> to 4GB it may be remapping for the AGP apature or something similar which
> is shifting memory up above the boundary.
> 


-- 
Mel Gorman
Part-time Phd Student                          Linux Technology Center
University of Limerick                         IBM Dublin Software Lab

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