scheduler tunables with contest - max_timeslice

Using the osdl (http://www.osdl.org) resources provided to me I'm running a series of contest benchmarks on 2.5.52-mm1 and modifying the scheduler tunables as provided by RML's patch. SMP used to minimise how long it will take me to do these. This is the first in the series and I've run a range of max_timeslices (default is 300ms; range 100-400):

noload:

Kernel [runs]           Time    CPU%    Loads   LCPU%   Ratio
2.5.52-mm1 [8]          39.7    180     0       0       1.10
max_tim100 [3]          39.7    180     0       0       1.10
max_tim200 [3]          39.6    180     0       0       1.09
max_tim400 [3]          39.7    181     0       0       1.10

cacherun:

Kernel [runs]           Time    CPU%    Loads   LCPU%   Ratio
2.5.52-mm1 [7]          36.9    194     0       0       1.02
max_tim100 [3]          36.7    194     0       0       1.01
max_tim200 [3]          36.8    193     0       0       1.02
max_tim400 [3]          36.8    194     0       0       1.02

process_load:

Kernel [runs]           Time    CPU%    Loads   LCPU%   Ratio
2.5.52-mm1 [7]          49.0    144     10      50      1.35
max_tim100 [3]          52.5    133     14      60      1.45
max_tim200 [3]          47.8    150     9       43      1.32
max_tim400 [3]          48.3    146     10      48      1.33

Slight balance change here. Note process load forks off 4*num_cpus processes that do their task in a very short time and shortening the max timeslice seems to slightly favour these tasks at the expense of kernel compilation time.

ctar_load:

Kernel [runs]           Time    CPU%    Loads   LCPU%   Ratio
2.5.52-mm1 [7]          55.5    156     1       10      1.53
max_tim100 [3]          56.0    156     1       10      1.55
max_tim200 [3]          53.9    162     1       10      1.49
max_tim400 [3]          55.5    148     1       10      1.53

xtar_load:

Kernel [runs]           Time    CPU%    Loads   LCPU%   Ratio
2.5.52-mm1 [7]          77.4    122     1       8       2.14
max_tim100 [3]          73.0    123     1       8       2.02
max_tim200 [3]          82.5    115     1       8       2.28
max_tim400 [3]          82.8    117     1       9       2.29

io_load:

Kernel [runs]           Time    CPU%    Loads   LCPU%   Ratio
2.5.52-mm1 [7]          80.5    108     10      19      2.22
max_tim100 [3]          93.8    100     13      20      2.59
max_tim200 [3]          88.8    98      12      19      2.45
max_tim400 [3]          71.4    114     8       18      1.97

The trend here is one of definite shortening of duration of kernel compilation during io load as the max timeslice is made longer

io_other:

Kernel [runs]           Time    CPU%    Loads   LCPU%   Ratio
2.5.52-mm1 [7]          60.1    131     7       18      1.66
max_tim100 [3]          64.5    127     8       19      1.78
max_tim200 [3]          62.8    125     8       19      1.73
max_tim400 [3]          62.5    126     6       15      1.73

read_load:

Kernel [runs]           Time    CPU%    Loads   LCPU%   Ratio
2.5.52-mm1 [7]          49.9    149     5       6       1.38
max_tim100 [3]          50.4    150     5       6       1.39
max_tim200 [3]          50.5    149     5       6       1.39
max_tim400 [3]          50.6    148     5       6       1.40

list_load:

Kernel [runs]           Time    CPU%    Loads   LCPU%   Ratio
2.5.52-mm1 [7]          43.8    167     0       9       1.21
max_tim100 [3]          44.2    166     0       9       1.22
max_tim200 [3]          43.6    168     0       9       1.20
max_tim400 [3]          43.3    167     0       9       1.20

mem_load:

Kernel [runs]           Time    CPU%    Loads   LCPU%   Ratio
2.5.52-mm1 [7]          71.1    123     36      2       1.96
max_tim100 [3]          81.1    100     38      2       2.24
max_tim200 [3]          84.1    101     36      2       2.32
max_tim400 [3]          82.8    97      36      2       2.29

No idea what's going on in mem_load

I will continue to do these with some of the other scheduler tunables. I will need recommendations if anyone is interested in further resolution testing than that I'm currently doing.

Con

Thanks, Con.

Some ideas...

Try child_penalty=50,75 (default is 95%)

Try max_sleep_avg=500,1000,4000 (default is 2000ms)

Try prio_bonus_ratio=0,10,30,50 (default is 25%)

Try starvation_limit=1000 (default is 2000ms)

Some of these are just academic, although I am curious about child_penalty and starvation_limit. In other cases, we can assuredly improve interactivity but we have to worry about throughput and starvation. Nonetheless, I am curious as to what you will find. :)

Robert Love