Re: [PATCH 12/14] vmscan: Do not writeback pages in direct reclaim

[KOSAKI Motohiro]

> On Tue, Jul 06, 2010 at 09:36:41AM +0900, KOSAKI Motohiro wrote:
> > Hello,
> > 
> > > Ok, that's reasonable as I'm still working on that patch. For example, the
> > > patch disabled anonymous page writeback which is unnecessary as the stack
> > > usage for anon writeback is less than file writeback. 
> > 
> > How do we examine swap-on-file?
> > 
> 
> Anything in particular wrong with the following?
> 
> /*
>  * For now, only kswapd can writeback filesystem pages as otherwise
>  * there is a stack overflow risk
>  */
> static inline bool reclaim_can_writeback(struct scan_control *sc,
>                                         struct page *page)
> {
>         return !page_is_file_cache(page) || current_is_kswapd();
> }
> 
> Even if it is a swapfile, I didn't spot a case where the filesystems
> writepage would be called. Did I miss something?

Hmm...

Now, I doubt I don't understand your mention. Do you mean you intend to swtich task
stack when every writepage? It seems a bit costly. but otherwise write-page for anon
makes filesystem IO and stack-overflow.

Can you please elaborate your plan?



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