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        <para>Upon allocation request via function <code>frame_alloc()</code>,
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        <para>Upon allocation request via function <code>frame_alloc()</code>,
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        the frame allocator first tries to find a zone that can satisfy the
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        the frame allocator first tries to find a zone that can satisfy the
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        request (i.e. has the required amount of free frames). Once a suitable
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        request (i.e. has the required amount of free frames). Once a suitable
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        zone is found, the frame allocator uses the buddy allocator on the
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        zone is found, the frame allocator uses the buddy allocator on the
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        zone's buddy system to perform the allocation. During deallocation,
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        zone's buddy system to perform the allocation. If no free zone is
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        which is triggered by a call to <code>frame_free()</code>, the frame
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        found, the frame allocator tries to reclaim slab memory.</para>
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        allocator looks up the respective zone that contains the frame being
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        <para>During deallocation, which is triggered by a call to
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        deallocated. Afterwards, it calls the buddy allocator again, this time
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        <code>frame_free()</code>, the frame allocator looks up the respective
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        zone that contains the frame being deallocated. Afterwards, it calls
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        the buddy allocator again, this time to take care of deallocation
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        to take care of deallocation within the zone's buddy system.</para>
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        within the zone's buddy system.</para>
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      </formalpara>
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      </formalpara>
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    </section>
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    </section>
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    <section id="buddy_allocator">
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    <section id="buddy_allocator">
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      <indexterm>
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      <indexterm>
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          <para>Whatever entities are allocated by the buddy allocator, the
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          <para>Whatever entities are allocated by the buddy allocator, the
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          first entity within a block is used to represent the entire block.
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          first entity within a block is used to represent the entire block.
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          The first entity keeps the order of the whole block. Other entities
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          The first entity keeps the order of the whole block. Other entities
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          within the block are assigned the magic value
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          within the block are assigned the magic value
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          <constant>BUDDY_INNER_BLOCK</constant>. This is especially important
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          <constant>BUDDY_SYSTEM_INNER_BLOCK</constant>. This is especially important
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          for effective identification of buddies in a one-dimensional array
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          for effective identification of buddies in a one-dimensional array
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          because the entity that represents a potential buddy cannot be
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          because the entity that represents a potential buddy cannot be
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          associated with <constant>BUDDY_INNER_BLOCK</constant> (i.e. if it
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          associated with <constant>BUDDY_SYSTEM_INNER_BLOCK</constant> (i.e. if it
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          is associated with <constant>BUDDY_INNER_BLOCK</constant> then it is
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          is associated with <constant>BUDDY_SYSTEM_INNER_BLOCK</constant> then it is
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          not a buddy).</para>
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          not a buddy).</para>
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        </formalpara>
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        </formalpara>
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      </section>
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      </section>
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    </section>
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    </section>
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        <secondary>- slab cache</secondary>
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        <secondary>- slab cache</secondary>
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      </indexterm>
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      </indexterm>
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      <para>Slabs of one object type are organized in a structure called slab
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      <para>Slabs of one object type are organized in a structure called slab
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      cache. There are ususally more slabs in the slab cache, depending on
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      cache. There are usually more slabs in the slab cache, depending on
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      previous allocations. If the the slab cache runs out of available slabs,
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      previous allocations. If the the slab cache runs out of available slabs,
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      new slabs are allocated. In order to exploit parallelism and to avoid
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      new slabs are allocated. In order to exploit parallelism and to avoid
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      locking of shared spinlocks, slab caches can have variants of
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      locking of shared spinlocks, slab caches can have variants of
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      processor-private slabs called magazines. On each processor, there is a
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      processor-private slabs called magazines. On each processor, there is a
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      two-magazine cache. Full magazines that are not part of any
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      two-magazine cache. Full magazines that are not part of any