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SubjectRe: VM test on 2.4.13-pre3aa1 (compared to 2.4.12-aa1 and 2.4.13-pre2aa1)
On Wed, Oct 17, 2001 at 04:31:03AM +0200, Andrea Arcangeli wrote:
> I noticed that anotehr thing that changed between vanilla 2.4.13pre2 and
> 2.4.13pre3 is the setting of page_cluster on machine with lots of ram.
> You'll now find the page_cluster set to 6, that means "1 << 6 << 12"
> bytes will be paged in at each major fault, while previously only "1 <<
> 4 << 12" bytes were paged in.
> So I'd suggest to try again after "echo 4 > /proc/sys/vm/page-cluster"
> to see if it makes any difference.
> Andrea

You Rule!

The tweak to page-cluster is basically magic for this test.

With page-cluster=4, the mp3blaster sputtered like 2.4.13pre2aa1.
Better, but not beautiful.

Real beauty happens with page-cluster=2. There is virtually no sputter.
And the wall clock time is a little better than 2.4.13pre2aa1!

I don't know what page-cluster size is best for everything, but
2.4.12aa1 (which was very good IMHO), sputtered about 10 seconds per
iteration, and each iteration took 64 seconds.

2.4.13pre3aa1 with no sputters: 48 seconds.


Also, interactive "feel" is much better too. This test would
really brutalize keyboard response. With 2.4.13-pre3aa1 and
page-cluster=2, the box is still usable. (for more than listening
to mp3's :))

page-cluster = 6

Averages for 10 mtest01 runs
bytes allocated: 1236166246
User time (seconds): 2.299
System time (seconds): 2.951
Elapsed (wall clock) time: 41.969
Percent of CPU this job got: 12.00
Major (requiring I/O) page faults: 113.5
Minor (reclaiming a frame) faults: 302580.3

page-cluster = 4

Averages for 10 mtest01 runs
bytes allocated: 1237529395
User time (seconds): 2.097
System time (seconds): 2.788
Elapsed (wall clock) time: 49.394
Percent of CPU this job got: 9.50
Major (requiring I/O) page faults: 120.3
Minor (reclaiming a frame) faults: 302914.1

page-cluster = 2

Averages for 10 mtest01 runs
bytes allocated: 1239521689
User time (seconds): 2.051
System time (seconds): 2.785
Elapsed (wall clock) time: 47.878
Percent of CPU this job got: 9.80
Major (requiring I/O) page faults: 114.0
Minor (reclaiming a frame) faults: 303399.7

The wall clock time went up somewhat from page-cluster=6.
Here is where we were before:


Averages for 10 mtest01 runs
bytes allocated: 1245184000
User time (seconds): 2.050
System time (seconds): 2.874
Elapsed (wall clock) time: 49.513
Percent of CPU this job got: 9.70
Major (requiring I/O) page faults: 115.6
Minor (reclaiming a frame) faults: 304781.9


Averages for 10 mtest01 runs
bytes allocated: 1253362892
User time (seconds): 2.099
System time (seconds): 2.823
Elapsed (wall clock) time: 64.109
Percent of CPU this job got: 7.50
Major (requiring I/O) page faults: 135.2
Minor (reclaiming a frame) faults: 306779.8

Randy Hron

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