Re: [PATCHv2, RFC 14/30] thp, mm: naive support of thp in genericread/write routines

[Kirill A. Shutemov]

Dave Hansen wrote:
> On 03/14/2013 10:50 AM, Kirill A. Shutemov wrote:
> > From: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>
> > 
> > For now we still write/read at most PAGE_CACHE_SIZE bytes a time.
> > 
> > This implementation doesn't cover address spaces with backing store.
> ...
> > --- a/mm/filemap.c
> > +++ b/mm/filemap.c
> > @@ -1165,12 +1165,23 @@ find_page:
> >  			if (unlikely(page == NULL))
> >  				goto no_cached_page;
> >  		}
> > +		if (PageTransTail(page)) {
> > +			page_cache_release(page);
> > +			page = find_get_page(mapping,
> > +					index & ~HPAGE_CACHE_INDEX_MASK);
> > +			if (!PageTransHuge(page)) {
> > +				page_cache_release(page);
> > +				goto find_page;
> > +			}
> > +		}
> 
> So, we're going to do a read of a file, and we pulled a tail page out of
> the page cache.  Why can't we just deal with the tail page directly?

Good point. I'll redo it once again.

First I thought to make it possible to read/write more PAGE_SIZE at once.
If not take this option in account for now, it's possible to make code much
cleaner.

-- 
 Kirill A. Shutemov
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