Re: [patch 3/9] mempool - Make mempools NUMA aware

[Sridhar Samudrala <sri@us.ibm.com>]

Pavel Machek wrote:
>>>> I still think some sort of reserve pool
>>>> is necessary to give the networking stack a little breathing room when
>>>> under both memory pressure and network load.
>>>>    
>>>>         
>>> "Lets throw some memory there and hope it does some good?" Eek? What
>>> about auditing/fixing the networking stack, instead?
>>>  
>>>       
>> The other reason we need a separate critical pool is to satifsy critical 
>> GFP_KERNEL allocations
>> when we are in emergency. These are made in the send side and we cannot 
>> block/sleep.
>>     
>
> If sending routines can work with constant ammount of memory, why use
> kmalloc at all? Anyway I thought we were talking receiving side
> earlier in the thread.
>
> Ouch and wait a moment. You claim that GFP_KERNEL allocations can't
> block/sleep? Of course they can, that's why they are GFP_KERNEL and
> not GFP_ATOMIC.
>   
I didn't meant GFP_KERNEL allocations cannot block/sleep? When in 
emergency, we
want even the GFP_KERNEL allocations that are made by critical sockets 
not to block/sleep.
So my original critical sockets patches changes the gfp flag passed to 
these allocation requests
to GFP_KERNEL|GFP_CRITICAL.

Thanks
Sridhar

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