>> With CONFIG_SPARSEMEM_EXTREME, the two level of memory section
>> descriptors are allocated from slab or bootmem. When allocating
>> from slab, let slab allocator to clear the memory chunk. However,
>> the memory chunk from bootmem allocator, we have to clear that
>> explicitly.
>
>I am sorry but I do not see how this optimize the current code. What is
>the difference between slab doing memset and doing it explicitly for all
>cases?
>
Yeah, I do agree it won't do much optimization here. However, I'm wandering
if I can remove the whole peice of code doing memset(setion, 0, array_size)
since it seems that alloc_bootmem_node() also clears the allocated memory
chunk :-)
Please correct me if I'm wrong about alloc_bootmem_node() :-)
Thanks,
Gavin
>>
>> Signed-off-by: Gavin Shan <shangw@xxxxxxxxxxxxxxxxxx>
>> ---
>> mm/sparse.c | 12 ++++++------
>> 1 file changed, 6 insertions(+), 6 deletions(-)
>>
>> diff --git a/mm/sparse.c b/mm/sparse.c
>> index afd0998..ce50c8b 100644
>> --- a/mm/sparse.c
>> +++ b/mm/sparse.c
>> @@ -74,14 +74,14 @@ static struct mem_section noinline __init_refok *sparse_index_alloc(int nid)
>>
>> if (slab_is_available()) {
>> if (node_state(nid, N_HIGH_MEMORY))
>> - section = kmalloc_node(array_size, GFP_KERNEL, nid);
>> + section = kzalloc_node(array_size, GFP_KERNEL, nid);
>> else
>> - section = kmalloc(array_size, GFP_KERNEL);
>> - } else
>> + section = kzalloc(array_size, GFP_KERNEL);
>> + } else {
>> section = alloc_bootmem_node(NODE_DATA(nid), array_size);
>> -
>> - if (section)
>> - memset(section, 0, array_size);
>> + if (section)
>> + memset(section, 0, array_size);
>> + }
>>
>> return section;
>> }
>> --
>> 1.7.9.5
>>
>> --
>> To unsubscribe, send a message with 'unsubscribe linux-mm' in
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>> see: http://www.linux-mm.org/ .
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>
>--
>Michal Hocko
>SUSE Labs
>SUSE LINUX s.r.o.
>Lihovarska 1060/12
>190 00 Praha 9
>Czech Republic
>
>--
>To unsubscribe, send a message with 'unsubscribe linux-mm' in
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>see: http://www.linux-mm.org/ .
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>
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