Re: [PATCH 02/10] vmscan: move priority variable into scan_control

[KOSAKI Motohiro]

Hi

> Sorry for the long delay on this. I got distracted by the anon_vma and
> page migration stuff.

Sorry for the delay too. I don't have enough development time recently ;)
I had tested this patch series a while. but now they need to rebase and retest. that's sad.

> On Sat, Apr 17, 2010 at 12:48:20AM +0200, Johannes Weiner wrote:
> > On Thu, Apr 15, 2010 at 06:21:35PM +0100, Mel Gorman wrote:
> > > From: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
> > > 
> > > Now very lots function in vmscan have `priority' argument. It consume
> > > stack slightly. To move it on struct scan_control reduce stack.
> > 
> > I don't like this much because it obfuscates value communication.
> > 
> > Functions no longer have obvious arguments and return values, as it's all
> > passed hidden in that struct.
> > 
> > Do you think it's worth it?  I would much rather see that thing die than
> > expand on it...
> 
> I don't feel strongly enough to fight about it and reducing stack usage here
> isn't the "fix" anyway. I'll drop this patch for now.

I'm ok either.


> That aside, the page reclaim algorithm maintains a lot of state and the
> "priority" is part of that state. While the struct means that functions might
> not have obvious arguments, passing the state around as arguments gets very
> unwieldly very quickly. I don't think killing scan_control would be as
> nice as you imagine although I do think it should be as small as
> possible.

I don't have strong opinion. I think both you and Hannes were talking correct thing.
But Hannes seems to have more strong opinion. then, I'm tend to drop this one.

Thanks.


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