Re: [ck] Re: -mm merge plans for 2.6.23

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Matthew Hawkins wrote:
On 7/25/07, Nick Piggin <[email protected]> wrote:

I guess /proc/meminfo, /proc/zoneinfo, /proc/vmstat, /proc/slabinfo
before and after the updatedb run with the latest kernel would be a
first step. top and vmstat output during the run wouldn't hurt either.


Hi Nick,

I've attached two files with this kind of info.  Being up at the cron
hours of the morning meant I got a better picture of what my system is
doing.  Here's a short summary of what I saw in top:

beagleindexer used gobs of ram.  600M or so (I have 1G)

Hmm OK, beagleindexer. I thought beagle didn't need frequent reindexing
because of inotify? Oh well...


updatedb didn't use much ram, but while it was running kswapd kept on
frequenting the top 10 cpu hogs - it would stick around for 5 seconds
or so then disappear for no more than 10 seconds, then come back
again.  This behaviour persisted during the run.  updatedb ran third
(beagleindexer was first, then update-dlocatedb)

Kswapd will use CPU when memory is low, even if there is no swapping.

Your "buffers" grew by 600% (from 50MB to 350MB), and slab also grew
by a few thousand entries. This is not just a problem when it pushes
out swap, it will also harm filebacked working set.

This (which Ray's traces also show) is a bit of a problem. As Andrew
noticed, use-once isn't working well for buffer cache, and it doesn't
really for dentry and inode cache either (although those don't seem
to be as much of a problem on your workload).

Andrew has done a little test patch for this in -mm, but it probably
wants more work and testing. If you can test the -mm kernel and see
if things are improved, that would help.

--
SUSE Labs, Novell Inc.
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