Re: [interbench numbers] Re: interactive task starvation

Mike Galbraith
2006-03-23T11:06:56Z

On Thu, 2006-03-23 at 06:53 +0100, Mike Galbraith wrote:
> On Thu, 2006-03-23 at 16:43 +1100, Con Kolivas wrote:
> > On Thu, 23 Mar 2006 02:22 pm, Mike Galbraith wrote:
> > > On Thu, 2006-03-23 at 07:27 +1100, Con Kolivas wrote:
> > > > I wonder why the results are affected even without any throttling
> > > > settings but just patched in? Specifically I'm talking about deadlines
> > > > met with video being sensitive to this. Were there any other config
> > > > differences between the tests? Changing HZ would invalidate the results
> > > > for example. Comments?
> > >
> > > I wondered the same. The only difference then is the lower idle sleep
> > > prio, tighter timeslice enforcement, and the SMP buglet fix for now <
> > > p->timestamp due to SMP rounding. Configs are identical.
> >
> > Ok well if we're going to run with this set of changes then we need to assess
> > the affect of each change and splitting them up into separate patches would
> > be appropriate normally anyway. That will allow us to track down which
> > particular patch causes it. That won't mean we will turn down the change
> > based on that one result, though, it will just help us understand it better.
>
> I'm investigating now.

Nothing conclusive. Some of the difference may be because interbench
has a dependency on the idle sleep path popping tasks in a prio 16
instead of 18. Some of it may be because I'm not restricting IO, doing
that makes a bit of difference. Some of it is definitely plain old
jitter.

Six hours is long enough. I'm all done chasing interbench numbers.

-Mike

virgin

--- Benchmarking simulated cpu of Video in the presence of simulated ---
Load Latency +/- SD (ms) Max Latency % Desired CPU % Deadlines Met
None 0.031 +/- 0.396 16.7 100 99.9
X 0.722 +/- 3.35 30.7 100 97
Burn 0.531 +/- 7.42 246 99.1 98
Write 0.302 +/- 2.31 40.4 99.9 98.5
Read 0.092 +/- 1.11 32.9 99.9 99.7
Compile 0.428 +/- 2.77 36.3 99.9 97.9
Memload 0.235 +/- 3.3 104 99.5 99.1

throttle patches with throttling disabled

--- Benchmarking simulated cpu of Video in the presence of simulated ---
Load Latency +/- SD (ms) Max Latency % Desired CPU % Deadlines Met
None 0.185 +/- 1.6 18.8 100 99.1
X 1.27 +/- 4.47 27 100 94.3
Burn 1.57 +/- 13.3 345 98.1 93
Write 0.819 +/- 3.76 34.7 99.9 96
Read 0.301 +/- 2.05 18.7 100 98.5
Compile 4.22 +/- 12.9 233 92.4 80.2
Memload 0.624 +/- 3.46 66.7 99.6 97

minus idle sleep

--- Benchmarking simulated cpu of Video in the presence of simulated ---
Load Latency +/- SD (ms) Max Latency % Desired CPU % Deadlines Met
None 0.222 +/- 1.82 16.8 100 98.8
X 1.02 +/- 3.9 30.7 100 95.7
Burn 0.208 +/- 3.67 141 99.8 99.3
Write 0.755 +/- 3.62 37.2 99.9 96.4
Read 0.265 +/- 1.94 16.9 100 98.6
Compile 2.16 +/- 15.2 333 96.7 90.7
Memload 0.723 +/- 3.5 37.4 99.8 96.3

minus don't restrict IO

--- Benchmarking simulated cpu of Video in the presence of simulated ---
Load Latency +/- SD (ms) Max Latency % Desired CPU % Deadlines Met
None 0.226 +/- 1.82 16.8 100 98.8
X 1.38 +/- 4.68 49.4 99.9 93.9
Burn 0.513 +/- 9.62 339 98.8 98.4
Write 0.418 +/- 2.7 30.8 99.9 97.9
Read 0.565 +/- 2.99 16.7 100 96.8
Compile 1.05 +/- 13.6 545 99.1 95.1
Memload 0.345 +/- 3.23 80.5 99.8 98.5