On Thu, 11 Aug 2005, Song Jiang wrote:

My machine has 2GB memory.
The size of the file to be scanned is 2.5GB.

Meanwhile, Clock-Pro is supposed to do a better job, because
part of the file can be protected in the active list and get
a decent number of hits.

Active:          11356 kB
Inactive:      1994400 kB

There is an error somewhere in my implementation of Clock-Pro.

I have made some tweaks but haven't found a proper fix yet.

The problem is that if I make things too well in favor of the
evicted pages, then pages on the active list may get replaced
by pages that have the _same_ inter-reference distance, which
would result in similarly bad behaviour.

Eyeballs on vmscan.c, nonresident.c and clockpro.c would be
very much appreciated ;)

Here is from /proc/refaults:     

    Refault distance          Hits
         0 -     32768           192
    32768 -     65536           269
    65536 -     98304           447
    98304 -    131072           603
   131072 -    163840          1087
   163840 -    196608           909
   196608 -    229376           558
   229376 -    262144           404
   262144 -    294912           287
   294912 -    327680           191
   327680 -    360448            79
   360448 -    393216            68
   393216 -    425984            41
   425984 -    458752            45
   458752 -    491520            31
New/Beyond    491520          2443

In the statistic, we do see many hits at the distance of around 
150,000 pages. If we consider the inactive list size (1.9GB), 
this position corresponds to the file size. However, if everything
happens as expected, all the hits should happen at the
distance. Unfortunately, there are also many hits listed as
New/Beyond. Because "Beyond"s should not be there, are they all
"New"s? Futhermore, I didn't see where the refault_histogram 
statistics get reset, though they almost stop increasing after
the first run. Can you show me that? 

Currently the statistics never get reset.

The number of "new/beyond" sounds about right for the
startup of a fully running Linux system.

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