Re: slab fragmentation ?

[Manfred Spraul <manfred@colorfullife.com>]

Badari Pulavarty wrote:

>>The fix would be simple: kmem_cache_alloc_node must walk through the 
>>list of partial slabs and check if it finds a slab from the correct 
>>node. If it does, then just use that slab instead of allocating a new 
>>one. And statistics must be added to kmem_cache_alloc_node - I forgot 
>>that when I wrote the function.
>>    
>>
>
>I will add more debug to find out if this is happening or not.
>
>What stats you want me to update in kmem_cache_alloc_node() ?
>
>  
>
I would just add a printk to confirm our suspicion. 
"kmem_cache_alloc_node called" + dump_stack(). I always use that 
approach, thus I forgot to add proper statistics.

For the final fix:
Add a field to struct kmem_cache_s. Something like "unsigned long 
alloc_node" or so. Add a STATS_INC_ALLOC_NODE macro and use it. Export 
the field value in the globalstat block (see s_show() near the end of 
slab.c) and increase the version number to 2.1 (in s_start()).

--
    Manfred
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