Re: RFT: updatedb "morning after" problem [was: Re: -mm mergeplans for 2.6.23]

[Mike Galbraith]

On Fri, 2007-07-27 at 03:00 -0700, Andrew Morton wrote:
> On Fri, 27 Jul 2007 01:47:49 -0700 Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote:
> 
> > More sophisticated testing is needed - there's something in
> > ext3-tools which will mmap, page in and hold a file for you.
> 
> So much for that theory.  afaict mmapped, active pagecache is immune to
> updatedb activity.  It just sits there while updatedb continues munching
> away at the slab and blockdev pagecache which it instantiated.  I assume
> we're never getting the VM into enough trouble to tip it over the
> start-reclaiming-mapped-pages threshold (ie: /proc/sys/vm/swappiness).
> 
> Start the updatedb on this 128MB machine with 80MB of mapped pagecache, it
> falls to 55MB fairly soon and then never changes.
> 
> So hrm.  Are we sure that updatedb is the problem?  There are quite a few
> heavyweight things which happen in the wee small hours.

The balance in _my_ world seems just fine.  I don't let any of those
system maintenance things run while I'm using the system, and it doesn't
bother me if my working set has to be reconstructed after heavy-weight
maintenance things are allowed to run.  I'm not seeing anything I
wouldn't expect to see when running a job the size of updatedb.

	-Mike

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