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On Fri, 27 Dec 2002 09:00 pm, Con Kolivas wrote:
> On Fri, 27 Dec 2002 04:46 pm, Con Kolivas wrote:
> > Here is a family of contest benchmarks using the osdl hardware in
> > uniprocessor mode on 2.5.53-mm1 while varying vm swappiness. s020 is vm
> > swappiness=20 and so on:
>
> SNIP--->
SNIP SNIP -->
akpm was the first to suggest these results looked unusual and suggested
running them in a single sitting. The thing is, I ran these in a single
sitting without rebooting over about 12 hours sequentially so I thought I'd
try a different approach. Look at this first set rearranged in the order I
tested them:
> dbench_load:
> Kernel [runs] Time CPU% Loads LCPU% Ratio
> s000 [3] 191.6 41 1 43 2.87
> s020 [5] 195.5 40 1 44 2.93
> s040 [5] 197.9 41 1 43 2.96
> s060 [5] 331.4 32 0 23 4.96
> s080 [5] 439.4 24 0 10 6.58
> s100 [5] 883.6 13 1 9 13.24
> s050 [5] 914.6 15 0 6 13.70
It appeared to take longer to run the longer the machine had been running,
even though all memory is "flushed" and swap is turned on/off before each
run. So I ran these again with a reboot between each run:
sw000 [5] 185.1 42 1 42 2.77
sw020 [5] 199.9 39 1 44 2.99
sw040 [5] 210.5 38 2 45 3.15
sw050 [5] 199.7 39 2 46 2.99
sw060 [5] 190.3 41 1 45 2.85
sw080 [5] 196.1 40 1 44 2.94
sw100 [5] 198.7 40 1 43 2.98
Well these look rather different shall we say? There's virtually no change
regardless of the swappiness setting.
Question. Why does the above happen when the machine has been running for a
while? All the file writes are deleted between each run so the filesystem
doesnt change that dramatically, but even if it was the change to the
filesystem, why does a reboot fix it? (ext3 throughout)
Is there something about the filesystem layer or elsewhere in the kernel that
could decay or fragment over time that only a reboot can fix? This would seem
to be a bad thing.
Comments?
Con
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This archive was generated by hypermail 2b29 : Tue Dec 31 2002 - 22:00:12 EST