Retest: Re: New VM Testcase (2.4.18pre7 SWAPS) (2.4.17-rmap12b OK)

From: Roger Larsson (roger.larsson@norran.net)
Date: Tue Feb 05 2002 - 18:15:36 EST


On Tuesdayen den 5 February 2002 01.36, Ed Tomlinson wrote:
> On February 4, 2002 05:24 pm, Roger Larsson wrote:
> > When examining Karlsbakk problem I got into one quite different myself.
> >
> > I have a 256MB UP PII 933 MHz.
> > When running the included program with an option of 200
> > (serving 200 clients with streaming data á 10MB... on first run
> > it creates the data, from /dev/urandom - overkill from /dev/null is ok!)
> >
> > ddteset.sh 200
> > [testcase initially written by Roy Sigurd Karlsbakk, he does not get
> > into this - but he has more RAM]
> >

I rerun the testcases, this time the 2.4.18-pre8 did not go as deep - and
survived. But had worse performance - then I remembered... I had added
file readahead. Retested again - it still survived...

echo "file_readahead:255"> /proc/ide/hda/settings

The results from all tested kernels standard and with readahead follows...

2.4.18pre7
        start: with 'bi' at 12000
        after awhile 'bi' hovers at 7000-9000 (sporadic swap outs)
        after yet some time it starts to swap in too - but without performance loss

2.4.18pre7 with file_readahead:255
        start: bi at 15000-18000
        after awhile heavy swap out: 600(!)-10000
        after yet some time, now with swap in too: 1000-6000

2.4.18pre7 w. Ed Tomlinsons patch
        start: bi at 12000
        stays at: 9000-12000
        more swapout causes throughput loss: 5000-9000
        but finally stabilizes at 7000-10000

2.4.18pre7 w. Ed Tomlinsons patch and file_readahead
        start: bi at 15000-23000
        ...
        rather soon ends up in both swapping in and out...
        (about the same throughput at 2.4.18pre7)

2.4.17rmap12c
        during the whole testrun: bi at 10000-12000
        exept for some short dips downto at most 8000

2.4.17rmap12c with file_readahead
        during whole testrun: bi at 20000-23000
        short dips downto 16000 (once 9000)

This should be a picture, but... some other day...

/RogerL

-- 
Roger Larsson
Skellefteå
Sweden
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