Re: Question: Is zone->prev_prirotiy used ?

[MinChan Kim <minchan.kim@gmail.com>]

On Thu, Jan 22, 2009 at 09:06:57AM +0900, KAMEZAWA Hiroyuki wrote:
> On Thu, 22 Jan 2009 08:54:07 +0900 (JST)
> KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> wrote:
> 
> > > On Wed, Jan 21, 2009 at 03:52:19PM +0900, KAMEZAWA Hiroyuki wrote:
> > > > Just a question.
> > > > 
> > > > In vmscan.c,  zone->prev_priority doesn't seem to be used.
> > > > 
> > > > Is it for what, now ?
> > > 
> > > It's the purpose of reclaiming mapped pages before split-lru.
> > > Now, get_scan_ratio can do it. 
> > > I think it is a meaningless variable.
> > > How about Kosaki and Rik ?
> > 
> > Right.
> > I thought this variable can use for future enhancement. 
> > then I didn't removed.
> > 
> example ?
> 
> > Kamezawa-san, does its variable prevent your development?
> > if so, I don't oppose removing.
> > 
> 
> Hmm, I tried to fix/clean up hierarchical-memory-reclaim + split-LRU and
> wondered where prev_priority should be recorded (hierarchy root or local or..)
> and found prev_priority is not used.
> 
> IMHO, LRU management is too complex to keep unnecessary code maintained just
> because it may be used in future. I personally like to rewrite better new code
> rather than reuse old ruins.

I agree. It's too complicated. 
I think it would be better to remove it. 
We can insert it again when we will really need it. 
 
> But I'm not in hurry. I just wanted to confirm.
> 
> BTW, I noticed mem_cgroup_calc_mapped_ratio() is not used, either ;)
> 
> Thanks,
> -Kame

--
Kinds Regards,
MinChan Kim

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