Re: Impact of scheduler tunables on interactive response (was Re: [BENCHMARK] scheduler tunables with contest - prio_bonus_ratio)

From: Bill Davidsen (davidsen@tmr.com)
Date: Wed Jan 01 2003 - 11:05:50 EST


On Wed, 1 Jan 2003, scott thomason wrote:

> I wrote a program that emulates a varying but constant set of loads
> with a fixed amount of sleep() time in the hopes that it would appear
> "interactive" to the estimator. The program measures the time it
> takes to process each iteration (minus the time it spends sleeping).
> Then I tried seven different configurations of the tunables while the
> system was under load. The kernel was 2.5.53-mm2. The load was a
> continuously looping kernel make -j4 clean/make -j4 bzImage, and a
> continuously looping copy of a 100MB file. My system is a dual AMD
> MP2000 with 1GB RAM.

This sounds very like my resp2 (www.unyuug.org/benchmarks/) program I
announced on this list some months ago, but resp2 generates loads of a
specific type so that you can determine of changes affect i/o load,
swapping load, CPU load, etc.

>
> *IF* the test program is valid--something I would like feedback
> on!--the results show that you can attack the background load with
> aggressive tunable settings to achieve low interactive response
> times, contrary to the direction Andrew had suggested taking for
> tunable settings.
>
> The seven tunable configurations, a graph of the results, and the raw
> data are here:
>
> http://www.thomasons.org/int_res.html
>
> Tab-delimited text and OpenOffice spreadsheets of the data are here:
>
> http://www.thomasons.org/int_res.txt
> http://www.thomasons.org/int_res.sxc
>
> I would like to assemble a small suite of tools that can be used to
> measure the impact of kernel changes on interactive performance,
> starting with Mark Hahn's/Andrew's "realfeel" microbenchmark and
> moving up thru whatever else may be necessary to gauge real-life
> impact. Your comments and direction are very welcome.

Note: the context switching benchmark is at the same URL. I have posted
some output recently, haven't had a of feedback other than some folks
mailing results to me without copying the list.

-- 
bill davidsen <davidsen@tmr.com>
  CTO, TMR Associates, Inc
Doing interesting things with little computers since 1979.

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