Messages in this thread | | | Subject | Re: [PATCH] ext4: slab caches set to SLAB_MEM_SPREAD flags. | From | Theodore Tso <> | Date | Wed, 16 Nov 2011 10:51:59 -0500 |
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On Nov 16, 2011, at 10:04 AM, Namjae Jeon wrote:
> If slab caches set to SLAB_MEM_SPREAD flags, The allocation is spread evenly over all the memory nodes instead of favoring allocation on the node local to current cpu.
And why do you think this is a good thing? For mballoc in particular, the data structures are used immediately and then freed immediately --- on the local node, so using a non-local memory just makes things worse in a NUMA system.
For the pageio, they are used immediately, and may end up getting freed on the same CPU if the I/O interrupt (and hence competion callbacks) happen on the same CPU that they are submitted on….
Regards,
-- Ted
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