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    12 <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>

    13 <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

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

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

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

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

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

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

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

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

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

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

    24 scheduler).</p> </section>

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

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

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

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

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

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

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

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

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

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

    35 Crazy scheduler in crazy priority mode does not impact the system

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

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

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

    39 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

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

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

    42 to do the following:<ul>

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

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

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

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

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

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

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

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

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

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

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

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

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

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

    57 scheduler:</p><ul>

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

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

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

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

    62 0 0 0 0 0</p></li>

    63 </ul></section>

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

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

    66 emulator, then:</p><ul>

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

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

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

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

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

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

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

    74 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

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

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

    77 <tbody>

    78 <row>

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

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

    81 </row>

    82 <row>

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

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

    85 </row>

    86 <row>

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

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

    89 </row>

    90 </tbody>

    91 </tgroup>

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

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

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

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

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

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

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

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

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

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

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

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

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

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

   106 above. </p></section>

   107 </conbody><related-links>

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

   109 Tools Overview</linktext></link>

   110 </related-links></concept>