scheduler tunables with contest - starvation_limit

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osdl, contest, tunable - starvation limit on 2.5.52-mm1

noload:

Kernel [runs]           Time    CPU%    Loads   LCPU%   Ratio
sta_lim1000 [3]         39.7    179     0       0       1.10
sta_lim2000 [3]         39.7    181     0       0       1.10

cacherun:

Kernel [runs]           Time    CPU%    Loads   LCPU%   Ratio
sta_lim1000 [3]         36.7    194     0       0       1.01
sta_lim2000 [3]         37.0    194     0       0       1.02

process_load:

Kernel [runs]           Time    CPU%    Loads   LCPU%   Ratio
sta_lim1000 [3]         48.2    146     10      47      1.33
sta_lim2000 [3]         45.6    157     7       37      1.26

ctar_load:

Kernel [runs]           Time    CPU%    Loads   LCPU%   Ratio
sta_lim1000 [3]         57.9    158     1       10      1.60
sta_lim2000 [3]         54.3    153     1       10      1.50

xtar_load:

Kernel [runs]           Time    CPU%    Loads   LCPU%   Ratio
sta_lim1000 [3]         72.9    125     1       8       2.01
sta_lim2000 [3]         67.6    130     1       9       1.87

io_load:

Kernel [runs]           Time    CPU%    Loads   LCPU%   Ratio
sta_lim1000 [3]         89.6    98      12      19      2.47
sta_lim2000 [3]         79.9    104     11      19      2.21

io_other:

Kernel [runs]           Time    CPU%    Loads   LCPU%   Ratio
sta_lim1000 [3]         68.1    124     8       19      1.88
sta_lim2000 [3]         68.5    116     9       20      1.89

read_load:

Kernel [runs]           Time    CPU%    Loads   LCPU%   Ratio
sta_lim1000 [3]         49.9    151     5       6       1.38
sta_lim2000 [3]         50.9    150     5       6       1.41

list_load:

Kernel [runs]           Time    CPU%    Loads   LCPU%   Ratio
sta_lim1000 [3]         43.8    167     0       9       1.21
sta_lim2000 [3]         43.5    168     0       9       1.20

mem_load:

Kernel [runs]           Time    CPU%    Loads   LCPU%   Ratio
sta_lim1000 [3]         106.8   77      36      2       2.95
sta_lim2000 [3]         112.4   73      36      2       3.10

Slight balance changes here. Most io things take slightly longer with lower starvation limit and mem_load takes less time.

Con
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Con, curiously, what is this OSDL hardware like?

One thing I always liked about your Contest runs were you did them on your home machine, which was presumably fairly run-of-the-mill so we could keep an eye on the low-end desktop machines.

Robert Love

one other thing that would be interesting to test on the osdl machines would be the effect of different filesystems.

the origional set of tests were all done on reiserfs, it would be interesting to see if there is a difference between it and the others.

David Lang

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The current osdl hardware uses ext3 in the default journalling mode. Trying different filesystems is something I have had planned for a while. When I get the hardware sorted out as I need it to do this I will post some results where comparisons can be made.

See the current specs here:
http://www.osdl.org/projects/ctdevel/results/

Con

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One thing I have found in doing low-latency research is the impact of ext3 over ext2. There is a periodic blip of high latency with ext3 not seen in ext2. Presumably due to the journal writeback of ext3.

It was not huge but a measurable increase. This was on 2.4, so I am curious how improved it is on 2.5.

Robert Love

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Sure. The osdl hardware is better than the laptop I used to use but in uniprocessor mode is fairly run of the mill. Its a PIII 866x2. The full hardware specs and archived major version results can be found here to be perused at your leisure:

http://www.osdl.org/projects/ctdevel/results/

Cheers,
Con
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Forgot to mention I've been doing the scheduler tunables in smp mode just so it wouldnt take me too long to get results. I have no doubt the signal to noise ratio is greater in the uniprocessor results though.

Con
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