kernel-ark/include/asm-cris
Badari Pulavarty f6b3ec238d [PATCH] madvise(MADV_REMOVE): remove pages from tmpfs shm backing store
Here is the patch to implement madvise(MADV_REMOVE) - which frees up a
given range of pages & its associated backing store.  Current
implementation supports only shmfs/tmpfs and other filesystems return
-ENOSYS.

"Some app allocates large tmpfs files, then when some task quits and some
client disconnect, some memory can be released.  However the only way to
release tmpfs-swap is to MADV_REMOVE". - Andrea Arcangeli

Databases want to use this feature to drop a section of their bufferpool
(shared memory segments) - without writing back to disk/swap space.

This feature is also useful for supporting hot-plug memory on UML.

Concerns raised by Andrew Morton:

- "We have no plan for holepunching!  If we _do_ have such a plan (or
  might in the future) then what would the API look like?  I think
  sys_holepunch(fd, start, len), so we should start out with that."

- Using madvise is very weird, because people will ask "why do I need to
  mmap my file before I can stick a hole in it?"

- None of the other madvise operations call into the filesystem in this
  manner.  A broad question is: is this capability an MM operation or a
  filesytem operation?  truncate, for example, is a filesystem operation
  which sometimes has MM side-effects.  madvise is an mm operation and with
  this patch, it gains FS side-effects, only they're really, really
  significant ones."

Comments:

- Andrea suggested the fs operation too but then it's more efficient to
  have it as a mm operation with fs side effects, because they don't
  immediatly know fd and physical offset of the range.  It's possible to
  fixup in userland and to use the fs operation but it's more expensive,
  the vmas are already in the kernel and we can use them.

Short term plan &  Future Direction:

- We seem to need this interface only for shmfs/tmpfs files in the short
  term.  We have to add hooks into the filesystem for correctness and
  completeness.  This is what this patch does.

- In the future, plan is to support both fs and mmap apis also.  This
  also involves (other) filesystem specific functions to be implemented.

- Current patch doesn't support VM_NONLINEAR - which can be addressed in
  the future.

Signed-off-by: Badari Pulavarty <pbadari@us.ibm.com>
Cc: Hugh Dickins <hugh@veritas.com>
Cc: Andrea Arcangeli <andrea@suse.de>
Cc: Michael Kerrisk <mtk-manpages@gmx.net>
Cc: Ulrich Drepper <drepper@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-06 08:33:22 -08:00
..
arch-v10 [PATCH] cris: "extern inline" -> "static inline" 2005-11-07 07:53:30 -08:00
arch-v32 [PATCH] cris: "extern inline" -> "static inline" 2005-11-07 07:53:30 -08:00
a.out.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
atomic.h [PATCH] atomic: inc_not_zero 2005-11-13 18:14:16 -08:00
auxvec.h [PATCH] auxiliary vector cleanups 2005-09-07 16:57:21 -07:00
axisflashmap.h [PATCH] CRIS update: misc patches 2005-07-27 16:26:00 -07:00
bitops.h [FLS64]: generic version 2006-01-03 13:11:06 -08:00
bug.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
bugs.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
byteorder.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
cache.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
cacheflush.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
checksum.h [PATCH] cris: "extern inline" -> "static inline" 2005-11-07 07:53:30 -08:00
cputime.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
current.h [PATCH] cris: "extern inline" -> "static inline" 2005-11-07 07:53:30 -08:00
delay.h [PATCH] cris: "extern inline" -> "static inline" 2005-11-07 07:53:30 -08:00
div64.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
dma-mapping.h [PATCH] gfp_t: dma-mapping (cris) 2005-10-28 08:16:48 -07:00
dma.h [PATCH] CRIS update: pci 2005-07-27 16:26:00 -07:00
elf.h [PATCH] CRIS update: arch split 2005-07-27 16:25:59 -07:00
emergency-restart.h [PATCH] Add emergency_restart() 2005-07-26 14:35:41 -07:00
errno.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
eshlibld.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
ethernet.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
etraxgpio.h [PATCH] CRIS update: arch split 2005-07-27 16:25:59 -07:00
etraxi2c.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
fasttimer.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
fcntl.h [PATCH] Clean up struct flock64 definitions 2005-09-07 16:57:38 -07:00
futex.h [PATCH] Remove unused var from asm/futex.h 2005-09-21 16:16:29 -07:00
hardirq.h [PATCH] CRIS update: IRQ 2005-07-27 16:26:00 -07:00
hw_irq.h [PATCH] CRIS update: IRQ 2005-07-27 16:26:00 -07:00
ide.h [PATCH] CRIS update: drivers 2005-07-27 16:25:59 -07:00
io.h [PATCH] cris: "extern inline" -> "static inline" 2005-11-07 07:53:30 -08:00
ioctl.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
ioctls.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
ipc.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
ipcbuf.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
irq.h [PATCH] cris: "extern inline" -> "static inline" 2005-11-07 07:53:30 -08:00
kmap_types.h [PATCH] CRIS update: updates for 2.6.12 2005-07-27 16:26:01 -07:00
linkage.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
local.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
mman.h [PATCH] madvise(MADV_REMOVE): remove pages from tmpfs shm backing store 2006-01-06 08:33:22 -08:00
mmu_context.h [PATCH] CRIS update: SMP 2005-07-27 16:26:01 -07:00
mmu.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
module.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
msgbuf.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
namei.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
page.h [PATCH] mm: consolidate get_order 2005-09-05 00:05:39 -07:00
param.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
pci.h [PATCH] CRIS update: pci 2005-07-27 16:26:00 -07:00
percpu.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
pgalloc.h [PATCH] cris: "extern inline" -> "static inline" 2005-11-07 07:53:30 -08:00
pgtable.h [PATCH] cris: "extern inline" -> "static inline" 2005-11-07 07:53:30 -08:00
poll.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
posix_types.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
processor.h [PATCH] fix remaining missing includes 2005-11-07 07:53:41 -08:00
ptrace.h [PATCH] CRIS update: profiler 2005-07-27 16:26:00 -07:00
resource.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
rs485.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
rtc.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
scatterlist.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
sections.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
segment.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
semaphore-helper.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
semaphore.h [PATCH] cris: "extern inline" -> "static inline" 2005-11-07 07:53:30 -08:00
sembuf.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
setup.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
shmbuf.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
shmparam.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
sigcontext.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
siginfo.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
signal.h [PATCH] asm/signal.h unification 2005-05-04 07:33:15 -07:00
smp.h [PATCH] CRIS update: SMP 2005-07-27 16:26:01 -07:00
socket.h [NET]: Introduce SO_{SND,RCV}BUFFORCE socket options 2005-08-29 15:31:35 -07:00
sockios.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
spinlock.h [PATCH] CRIS update: SMP 2005-07-27 16:26:01 -07:00
stat.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
statfs.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
string.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
sync_serial.h [PATCH] CRIS update: synchronous serial port driver 2005-07-27 16:26:01 -07:00
system.h [PATCH] cris: "extern inline" -> "static inline" 2005-11-07 07:53:30 -08:00
termbits.h [PATCH] CRIS update: synchronous serial port driver 2005-07-27 16:26:01 -07:00
termios.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
thread_info.h [PATCH] CRIS update: updates for 2.6.12 2005-07-27 16:26:01 -07:00
timex.h [PATCH] cris: "extern inline" -> "static inline" 2005-11-07 07:53:30 -08:00
tlb.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
tlbflush.h [PATCH] cris: "extern inline" -> "static inline" 2005-11-07 07:53:30 -08:00
topology.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
types.h [PATCH] sab: consolidate kmem_bufctl_t 2005-09-05 00:05:48 -07:00
uaccess.h [PATCH] cris: "extern inline" -> "static inline" 2005-11-07 07:53:30 -08:00
ucontext.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
unaligned.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
unistd.h [PATCH] cris: "extern inline" -> "static inline" 2005-11-07 07:53:30 -08:00
user.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00