Messages in this thread | | | Date | Tue, 09 Aug 2011 13:24:32 +0100 | From | "Jan Beulich" <> | Subject | Re: Subject: [PATCH V6 1/4] mm: frontswap: swap data structure changes |
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>>> On 08.08.11 at 22:45, Dan Magenheimer <dan.magenheimer@oracle.com> wrote: > From: Dan Magenheimer <dan.magenheimer@oracle.com> > Subject: [PATCH V6 1/4] mm: frontswap: swap data structure changes > > This first patch of four in the frontswap series makes available core > swap data structures (swap_lock, swap_list and swap_info) that are > needed by frontswap.c but we don't need to expose them to the dozens > of files that include swap.h so we create a new swapfile.h just to > extern-ify these. > > Also add frontswap-related elements to swap_info_struct. Frontswap_map > points to vzalloc'ed one-bit-per-swap-page metadata that indicates > whether the swap page is in frontswap or in the device and frontswap_pages > counts how many pages are in frontswap. We don't tie these to > CONFIG_FRONTSWAP to avoid unnecessary clutter around various frontswap > hooks. > > [v6: rebase to 3.0-rc1] > [v5: no change from v4] > [v4: rebase to 2.6.39] > Signed-off-by: Dan Magenheimer <dan.magenheimer@oracle.com> > Reviewed-by: Konrad Wilk <konrad.wilk@oracle.com> > Acked-by: Seth Jennings <sjenning@linux.vnet.ibm.com> > Cc: Jeremy Fitzhardinge <jeremy@goop.org> > Cc: Hugh Dickins <hughd@google.com> > Cc: Johannes Weiner <hannes@cmpxchg.org> > Cc: Nitin Gupta <ngupta@vflare.org> > Cc: Matthew Wilcox <matthew@wil.cx> > Cc: Chris Mason <chris.mason@oracle.com> > Cc: Jan Beulich <JBeulich@novell.com> > Cc: Rik Riel <riel@redhat.com> > Cc: Andrew Morton <akpm@linux-foundation.org> > > --- linux/include/linux/swapfile.h 1969-12-31 17:00:00.000000000 -0700 > +++ frontswap/include/linux/swapfile.h 2011-08-08 08:59:03.951694506 -0600 > @@ -0,0 +1,13 @@ > +#ifndef _LINUX_SWAPFILE_H > +#define _LINUX_SWAPFILE_H > + > +/* > + * these were static in swapfile.c but frontswap.c needs them and we don't > + * want to expose them to the dozens of source files that include swap.h > + */ > +extern spinlock_t swap_lock; > +extern struct swap_list_t swap_list; > +extern struct swap_info_struct *swap_info[]; > +extern int try_to_unuse(unsigned int, bool, unsigned long); > + > +#endif /* _LINUX_SWAPFILE_H */ > --- linux/include/linux/swap.h 2011-08-08 08:19:25.880690134 -0600 > +++ frontswap/include/linux/swap.h 2011-08-08 08:59:03.952691415 -0600 > @@ -194,6 +194,8 @@ struct swap_info_struct { > struct block_device *bdev; /* swap device or bdev of swap file */ > struct file *swap_file; /* seldom referenced */ > unsigned int old_block_size; /* seldom referenced */
#ifdef CONFIG_FRONTSWAP
> + unsigned long *frontswap_map; /* frontswap in-use, one bit per page */ > + unsigned int frontswap_pages; /* frontswap pages in-use counter */
#endif
(to eliminate any overhead with that config option unset)
Jan
> }; > > struct swap_list_t {
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