| 139,10 → 139,10 |
|---|
| thread exits, its kernel structure usually stays in memory, until the |
| thread is detached by another thread using <code>thread_detach()</code> |
| function. Terminated but undetached threads are in the |
| <constant>Undead</constant> state. When the thread is detached or |
| <constant>Lingering</constant> state. When the thread is detached or |
| detaches itself during its life, it is destroyed in the |
| <constant>Exiting</constant> state and the <constant>Undead</constant> |
| state is not reached.<figure float="1"> |
| <constant>Exiting</constant> state and the |
| <constant>Lingering</constant> state is not reached.<figure float="1"> |
| <title>Transitions among thread states.</title> |
| |
| <mediaobject id="thread_states" xreflabel=""> |
| 162,28 → 162,28 |
|---|
| </formalpara> |
| |
| <formalpara> |
| <title>Pseudo Threads</title> |
| <title>Fibrils</title> |
| |
| <para>HelenOS userspace layer knows even smaller units of execution. |
| Each userspace thread can make use of an arbitrary number of pseudo |
| threads. These pseudo threads have their own synchronous register |
| context, userspace code and stack. They live their own life within the |
| userspace thread and the scheduler does not have any idea about them |
| because they are completely implemented by the userspace library. This |
| implies several things:<itemizedlist> |
| Each userspace thread can make use of an arbitrary number of fibrils. |
| These fibrils have their own synchronous register context, userspace |
| code and stack. They live their own life within the userspace thread and |
| the scheduler does not have any idea about them because they are |
| completely implemented by the userspace library. This implies several |
| things:<itemizedlist> |
| <listitem> |
| <para>pseudothreads schedule themselves cooperatively within the |
| time slice given to their userspace thread,</para> |
| <para>fibrils schedule themselves cooperatively within the time |
| slice given to their userspace thread,</para> |
| </listitem> |
| |
| <listitem> |
| <para>pseudothreads share FPU context of their containing thread |
| <para>fibrils share FPU context of their containing thread |
| and</para> |
| </listitem> |
| |
| <listitem> |
| <para>all pseudothreads of one userspace thread block when one of |
| them goes to sleep.</para> |
| <para>all fibrils of one userspace thread block when one of them |
| goes to sleep.</para> |
| </listitem> |
| </itemizedlist></para> |
| </formalpara> |