linux-kernel - Re: [PATCH 4/4] Documentation/scheduler/sched-deadline.txt: add tests suite appendix

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Message-ID: <53EB2B42.1030506@arm.com>
Date:	Wed, 13 Aug 2014 10:09:22 +0100
From:	Juri Lelli <juri.lelli@....com>
To:	Randy Dunlap <rdunlap@...radead.org>,
	"peterz@...radead.org" <peterz@...radead.org>
CC:	"luca.abeni@...tn.it" <luca.abeni@...tn.it>,
	"mingo@...hat.com" <mingo@...hat.com>,
	"henrik@...tad.us" <henrik@...tad.us>,
	"raistlin@...ux.it" <raistlin@...ux.it>,
	"juri.lelli@...il.com" <juri.lelli@...il.com>,
	"linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 4/4] Documentation/scheduler/sched-deadline.txt: add tests
 suite appendix

Hi Randy,

On 12/08/14 18:57, Randy Dunlap wrote:
> On 08/12/14 08:49, Juri Lelli wrote:
>> Add an appendix briefly describing tools that can be used to test SCHED_DEADLINE
>> (and the scheduler in general). Links to where source code of the tools is hosted
>> are also provided.
>>
>> Signed-off-by: Juri Lelli <juri.lelli@....com>
>> Cc: Randy Dunlap <rdunlap@...radead.org>
>> Cc: Peter Zijlstra <peterz@...radead.org>
>> Cc: Ingo Molnar <mingo@...hat.com>
>> Cc: Henrik Austad <henrik@...tad.us>
>> Cc: Dario Faggioli <raistlin@...ux.it>
>> Cc: Juri Lelli <juri.lelli@...il.com>
>> Cc: linux-doc@...r.kernel.org
>> Cc: linux-kernel@...r.kernel.org
>> ---
>>  Documentation/scheduler/sched-deadline.txt |   52 ++++++++++++++++++++++++++++
>>  1 file changed, 52 insertions(+)
>>
>> diff --git a/Documentation/scheduler/sched-deadline.txt b/Documentation/scheduler/sched-deadline.txt
>> index d056034..52eb25f 100644
>> --- a/Documentation/scheduler/sched-deadline.txt
>> +++ b/Documentation/scheduler/sched-deadline.txt
>> @@ -15,6 +15,7 @@ CONTENTS
>>   5. Tasks CPU affinity
>>     5.1 SCHED_DEADLINE and cpusets HOWTO
>>   6. Future plans
>> + A. Test suite
>>  
>>  
>>  0. WARNING
>> @@ -339,3 +340,54 @@ CONTENTS
>>   throttling patches [https://lkml.org/lkml/2010/2/23/239] but we still are in
>>   the preliminary phases of the merge and we really seek feedback that would
>>   help us decide on the direction it should take.
>> +
>> +Appendix A. Test suite
>> +======================
>> +
>> + The SCHED_DEADLINE policy can be easily tested using two applications that
>> + are part of a wider Linux Scheduler validation suite. The suite is
>> + available as a GitHub repository: https://github.com/scheduler-tools.
>> +
>> + The first testing application is called rt-app and can be used to
>> + start multiple threads with specific parameters. rt-app supports
>> + SCHED_{OTHER,FIFO,RR,DEADLINE} scheduling policies and their related
>> + parameters (e.g., niceness, priority, runtime/deadline/period). rt-app
>> + is a valuable tool, as it can be used to synthetically recreate certain
>> + workloads (maybe mimicking real use-cases) and evaluate how the scheduler
>> + behaves under such workloads. In this way, results are easily reproducible.
>> + rt-app is available at: https://github.com/scheduler-tools/rt-app.
>> +
>> + Threads parameters can be specified from command line, with something like
> 
>     Thread                              from the
> 
>> + this:
>> +
>> +  # rt-app -t 100000:10000:d -t 150000:20000:f:10 -D5
>> +
>> + What above creates two threads, first one, scheduled by SCHED_DEADLINE,
> 
>     The above creates two threads. The first one,
> 
>> + executes for 10ms every 100ms and second one, scheduled at RT priority 10
> 
>                                   and the second one,
> 
>> + with SCHED_FIFO, executes for 20ms every 150ms. The configuration runs
>> + for 5 seconds.
>> +
>> + More interestingly, configurations can be described with a json file, that
> 
>                                                     drop comma here     ^
> 

All fixed.

Thanks a lot,

- Juri

>> + can be passed as input to rt-app with something like this:
>> +
>> +  # rt-app my_config.json
>> +
>> + The parameters that can be specified with the second method are a superset
>> + of the command line options. Please refer to rt-app documentation for more
>> + details.
>> +
>> + The second testing application is a modification of schedtool, called
>> + schedtool-dl, which can be used to setup SCHED_DEADLINE parameters for a
>> + certain pid/application. schedtool-dl is available at:
>> + https://github.com/scheduler-tools/schedtool-dl.git.
>> +
>> + The usage is straightforward:
>> +
>> +  # schedtool -E -t 10000000:100000000 -e ./my_cpuhog_app
>> +
>> + With this, my_cpuhog_app is put to run inside a SCHED_DEADLINE reservation
>> + of 10ms every 100ms (note that parameters are expressed in microseconds).
>> + You can also use schedtool to create a reservation for an already running
>> + application, given that you know its pid:
>> +
>> +  # schedtool -E -t 10000000:100000000 my_app_pid
>>
> 
> 

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