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<concept id="GUID-3D5974E9-0F6C-4BBE-AD41-C405DC286C09" xml:lang="en"><title>Crazy Scheduler</title><shortdesc>This document describes the crazy scheduler tool.</shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody>

<section id="GUID-BB5A11B3-4EEB-4DD1-A9CF-F0D38BC87527"><title>Introduction</title><p>The adding of new functionality to the kernel has meant that Inter-Process

Communication (IPC) is no longer deterministic.  The crazy scheduler

is a tool that is designed to simulate the effect of IPC calls occurring

at any time. With this tool, developers can check that their code

will still work with the latest version of the kernel.</p><p>Crazy

scheduler has two modes of operation:</p><ul>

<li><p>Crazy delays</p></li>

<li><p>Crazy priorities</p></li>

</ul><p><note>Both modes of operation should not be enabled simultaneously

since this could cause the system to deadlock.</note></p><p>Ideally,

the test cases should be run twice (once with each mode of the crazy

scheduler).</p> </section>

<section id="GUID-EE0742D8-4050-4307-BBF9-DE00B4CD9D0B"><title>Crazy

delay mode</title><p>This mode is used to test the effect of a delay

in threads moving between states.</p></section>

<section id="GUID-D104CF5B-22F6-4367-8220-3E213583C014"><title>Crazy

priority mode</title><p>This mode is used to test the effect of no

longer being able to rely on thread priority to synchronize IPC calls.

In this mode, an IPC call can occur at any time. </p></section>

<section id="GUID-D23075E3-C015-4ECF-A0E2-65553B3506E5"><title>Prerequisites</title><p>Your build should have the crazy scheduler present. It is present

in the udeb version of a build and is disabled by default.</p></section>

<section id="GUID-03C46CE1-6ED6-4448-A804-E023D25477E1"><title>Limitations</title><p>Crazy scheduler will only work on the udeb version of a build.

Crazy scheduler in crazy priority mode does not impact the system

as heavily as the crazy scheduler in crazy delay mode. Crazy Priority

mode can only be enabled at ROM time or boot time (for the emulator).

Do not expect this tool to find all the issues associated with IPC

and synchronization. The crazy delay mode will slow the system down.</p><p><note>When a build is booting with the crazy scheduler in crazy

delay mode enabled, the booting process can take a long time. In fact

it can appear that it has hung. To reduce the boot time, it is advisable

to do the following:<ul>

<li><p>Format the user NAND (C:) partition using a regular ROM image

before booting the build with the crazy scheduler enabled.</p></li>

</ul>It is advisable to execute the crazy scheduling tests on both

the emulator and on hardware. </note></p></section>

<section id="GUID-B7C2FAE4-4DA7-4678-BB9E-788E884BEDC4"><title>How

to enable the crazy scheduler</title><p>The Crazy scheduler can be

used on both the emulator and hardware builds.</p></section>

<section id="GUID-A0B0C64D-5366-47C7-9599-5E528855C36E"><title>Enabling

for hardware</title><p>If the crazy scheduler is to be executed on

hardware, then there are two ways to enable it:</p><ul>

<li><p>Add the parameters -DCRAZYSCHEDDELAY (for the crazy delay)

or -DCRAZYSCHEDPRIO (for crazy priority) to the buildrom arguments.

Do not enable both parameters at the same time.</p></li>

</ul><p>There are other ways of enabling the two modes of the crazy

scheduler:</p><ul>

<li><p>To enable the crazy priorities mode, include the following

line into the relevant iby/oby file:</p><p>CRAZYSCHEDULING(on)</p></li>

<li><p>To enable the crazy delay mode , include the following line

into the relevant iby/oby file: </p><p>kerneltrace 0x80000000 0 0x20

0 0 0 0 0</p></li>

</ul></section>

<section id="GUID-EEF30371-BF17-4C14-BC06-8C8C92E514DC"><title>Enabling

for the emulator</title><p>If the crazy scheduler is to run on the

emulator, then:</p><ul>

<li><p>To enable crazy delays, add the following line to the \epoc\data\epoc.ini

file:</p><p>debugmask2 0x20</p></li>

<li><p>To enable crazy priorities, add the following line to the \epoc32\data\epoc.ini

file:</p><p>crazyscheduling on</p></li>

</ul><p><note>Do not enable both crazy delays and crazy priorities

on at once.</note></p></section>

<section id="GUID-1D6341AB-D9F1-4F39-AD93-3DF0B408EE4A"><title>Runtime

enabling</title><p>The crazy delays can be toggled on or off at runtime.</p><p>To do this, EShell must be running. The following commands can

be used from within EShell:</p><table id="GUID-B3A9D71D-ED36-4FB4-AEB6-01B4C9AD78CF">

<tgroup cols="2"><colspec colname="col1"/><colspec colname="col2"/>

<tbody>

<row>

<entry><p><b>Command</b></p></entry>

<entry><p><b>Description</b></p></entry>

</row>

<row>

<entry><p>trace on 69</p></entry>

<entry><p>Enable crazy delays</p></entry>

</row>

<row>

<entry><p>trace off 69</p></entry>

<entry><p>Disable crazy delays</p></entry>

</row>

</tbody>

</tgroup>

</table><p><note>Crazy priority cannot be toggled on or off at runtime.</note></p></section>

<section id="GUID-B1284B69-ECCF-4265-A2A6-50C7AC0BD7BB"><title>State

of the crazy scheduler</title><p>The state of the crazy scheduler

can be obtained by executing the following in EShell:</p><ul>

<li><p>sysinfo</p></li>

</ul><p>The output will tell you which of the crazy scheduler modes

are enabled or disabled.</p></section>

<section id="GUID-582EB310-2404-455B-B9F8-59D1367D4E36"><title>How

to obtain the output from the crazy scheduler</title><p>The crazy

scheduler does not produce output as such, instead it is expected

to work in conjunction with other test tools. The only output from

this tool is whether an application will still work or not.</p></section>

<section id="GUID-C47E10B3-DA1F-47EE-BAB8-536055580C95"><title>How

to interpret the output from the crazy scheduler</title><p>As for

above. </p></section>

</conbody><related-links>

<link href="GUID-7FB63DAA-FBFD-4485-919F-5FEFBBC53B97.dita"><linktext>SMP

Tools Overview</linktext></link>

</related-links></concept>