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implement chain walking for arbitrary ->next pointer offsets in

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Mon Dec  5 15:53:20 2005  Tim Janik  <timj@imendio.com>

        * glib/gslice.c: implement chain walking for arbitrary ->next pointer
        offsets in g_slice_free_chain_with_offset() based on a patch by behdad
        in bug 323178. moved time consuming logic from g_slice_free() out of
        the inner loop, so g_slice_free_chain_with_offset() provides a real
        performance benefit over g_slice_free1() now.

        * glib/gslice.h: renamed g_slice_free_chain() to
        g_slice_free_chain_with_offset(). implemented g_slice_free_chain() as
        a type-safe macro as suggested in bug 323178.
        simplified the macro implementation of g_slice_free() and implemented
        it in a type safe manner for all compliers as suggested by Morten
        Welinder <mortenw@gnome.org>.

        * glib/gmain.c:
        * glib/glist.c:
        * glib/gslist.c:
        * glib/glib.symbols: s/g_slice_free_chain/g_slice_free_chain_with_offset/
This commit is contained in:
Tim Janik
2005-12-05 15:01:27 +00:00
committed by Tim Janik
parent 559e1057a0
commit 6ed79b115c
11 changed files with 183 additions and 64 deletions
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5
docs/reference/ChangeLog
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@@ -1,3 +1,8 @@
Mon Dec 5 15:53:37 2005 Tim Janik <timj@imendio.com>
* glib/tmpl/memory_slices.sgml: updates to new g_slice API
and minor fixes.
2005-12-05 Matthias Clasen <mclasen@redhat.com>
* gobject/tmpl/generic_values.sgml:

69
docs/reference/glib/tmpl/memory_slices.sgml
View File

@@ -6,18 +6,21 @@ efficient way to allocate groups of equal-sized chunks of memory.
<!-- ##### SECTION Long_Description ##### -->
<para>
Memory slices provide a space-efficient way to allocate equal-sized
pieces of memory, just like #GMemChunks, while avoiding their scalability
and performance problems.
Memory slices provide a space-efficient and multi processing scalable
way to allocate equal-sized pieces of memory, just like the original
#GMemChunks (from GLib <= 2.8), while avoiding their excessive
memroy-waste scalability and performance problems.
</para>
<para>
To achieve these goals, the slice allocator uses a sophisticated,
layered design that has been inspired by Bonwick's slab allocator
<footnote><para><ulink url="http://citeseer.ist.psu.edu/bonwick94slab.html">[Bonwick94]</ulink> Jeff Bonwick, The slab allocator: An object-caching kernel
<footnote><para>
<ulink url="http://citeseer.ist.psu.edu/bonwick94slab.html">[Bonwick94]</ulink> Jeff Bonwick, The slab allocator: An object-caching kernel
memory allocator. USENIX 1994, and
<ulink url="http://citeseer.ist.psu.edu/bonwick01magazines.html">[Bonwick01]</ulink> Bonwick and Jonathan Adams, Magazines and vmem: Extending the
slab allocator to many cpu's and arbitrary resources. USENIX 2001</para></footnote>.
<ulink url="http://citeseer.ist.psu.edu/bonwick01magazines.html">[Bonwick01]</ulink> Bonwick and Jonathan Adams, Magazines and vmem: Extending the
slab allocator to many cpu's and arbitrary resources. USENIX 2001
</para></footnote>.
It uses posix_memalign() to optimize allocations of many equally
sized chunks, and has per-thread free lists (the so-called magazine layer)
to quickly satisfy allocation requests of already known structure sizes.
@@ -94,17 +97,19 @@ object size used at allocation time is still available when freeing.
<!-- ##### FUNCTION g_slice_alloc ##### -->
<para>
Allocates a block of memory from the slice allocator.
The block adress handed out is guaranteed to be aligned
to at leats 2 * sizeof (void*).
</para>
@block_size: the number of bytes to allocate
@Returns: a pointer to the allocated
@Returns: a pointer to the allocated memory block
@Since: 2.10
<!-- ##### FUNCTION g_slice_alloc0 ##### -->
<para>
Allocates a block of memory from the slice allocator, setting the
memory to 0.
Allocates a block of memory via g_slice_alloc()
and initialize the returned memory to 0.
</para>
@block_size: the number of bytes to allocate
@@ -114,38 +119,48 @@ memory to 0.
<!-- ##### FUNCTION g_slice_free1 ##### -->
<para>
Frees a block of memory. The memory must have been allocated from
the slice allocator.
Frees a block of memory. The memory must have been allocated via
g_slice_alloc() or g_slice_alloc0()
and the @block_size has to match the size specified upon allocation.
</para>
@block_size: the size of the block
@mem_block: a pointer to the block to free
@Since: 2.10
<!-- ##### FUNCTION g_slice_free_chain ##### -->
<!-- ##### FUNCTION g_slice_free_chain_with_offset ##### -->
<para>
Frees a linked list of memory block. The memory blocks must be equal-sized,
allocated from the slice allocator and linked together by a
<literal>next</literal> pointer stored in the @next_offset's word of
each block.
Frees a linked list of memory blocks. The memory blocks must be equal-sized,
allocated via
g_slice_alloc() or g_slice_alloc0()
and linked together by a <literal>next</literal> pointer (similar to #GSList)
stored in the word of each block denoted by @next_offset.
The @block_size has to match the size specified upon allocation.
</para>
<para>
Currently, this function only supports blocks which store their
<literal>next</literal> pointer in the same position as #GSList.
Therefore, @next_offset must be 1.
</para>
@block_size: the size of the blocks
@mem_chain: a pointer to the first block
@next_offset: the offset of the <literal>next</literal> pointer
@Since: 2.10
<!-- ##### MACRO g_slice_free_chain ##### -->
<para>
Frees a linked list of memory blocks of structure type @type.
The memory blocks must be equal-sized, allocated via
g_slice_alloc() or g_slice_alloc0()
and linked together by a @next pointer (similar to #GSList). The name of the
@next field in @type is passed as third argument.
</para>
@type: the type of the @mem_chain blocks
@mem_chain: a pointer to the first block of the chain
@next: the field name of the next pointer in @type
@Since: 2.10
<!-- ##### MACRO g_slice_new ##### -->
<para>
A convenience macro to allocate a block of memory from the slice allocator.
It calls g_slice_alloc() and casts the returned pointer to a pointer to
the given type, avoiding a type cast in the source code.
It calls g_slice_alloc() with sizeof (@type) and casts the returned pointer
to a pointer of the given type, avoiding a type cast in the source code.
</para>
@type: the type to allocate, typically a structure name
@@ -156,9 +171,9 @@ the given type, avoiding a type cast in the source code.
<!-- ##### MACRO g_slice_new0 ##### -->
<para>
A convenience macro to allocate a block of memory from the slice allocator
and set the memory to 0. It calls g_slice_alloc0() and casts the returned
pointer to a pointer to the given type, avoiding a type cast in the source
code.
and set the memory to 0. It calls g_slice_alloc0() with sizeof (@type) and
casts the returned pointer to a pointer of the given type, avoiding a type
cast in the source code.
</para>
@type: the type to allocate, typically a structure name