|| ||Rik van Riel <riel-AT-redhat.com>|
|| ||Song Jiang <sjiang-AT-lanl.gov>|
|| ||Re: [PATCH/RFT 5/5] CLOCK-Pro page replacement|
|| ||Thu, 11 Aug 2005 21:22:11 -0400 (EDT)|
|| ||linux-mm-AT-kvack.org, linux-kernel-AT-vger.kernel.org|
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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