Re: [RFC][PATCH] page reclaim throttle take2

[Balbir Singh <balbir@linux.vnet.ibm.com>]

KOSAKI Motohiro wrote:
> Hi
> 
>>> I don't think so.
>>> all modern many cpu machine stand on NUMA.
>>> it mean following,
>>>  - if cpu increases, then zone increases, too.
>>>
>>> if default value increase by #cpus, lock contension dramatically increase
>>> on large numa.
>>>
>>> Have I overlooked anything?
>>>
>> How about adding something like..
>> == 
>> CONFIG_SIMULTANEOUS_PAGE_RECLAIMERS 
>> int
>> default 3
>> depends on DEBUG
>> help
>>   This value determines the number of threads which can do page reclaim
>>   in a zone simultaneously. If this is too big, performance under heavy memory
>>   pressure will decrease.
>>   If unsure, use default.
>> ==
>>
>> Then, you can get performance reports from people interested in this
>> feature in test cycle.
> 
> hm, intersting.
> but sysctl parameter is more better, i think.
> 
> OK, I'll add it at next post.

I think sysctl should be interesting. The config option provides good
documentation, but it is static in nature (requires reboot to change). I wish we
could have the best of both worlds.

-- 
	Warm Regards,
	Balbir Singh
	Linux Technology Center
	IBM, ISTL