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
..
8253pit.h
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a.out.h
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agp.h
[PATCH] AGP fix for Xen VMM
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agp_backend.h
Linux-2.6.12-rc2
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atomic.h
[PATCH] mm: fill arch atomic64 gaps
2005-11-23 16:08:39 -08:00
auxvec.h
[PATCH] auxiliary vector cleanups
2005-09-07 16:57:21 -07:00
barrier.h
[PATCH] fix alpha breakage
2005-10-29 21:40:35 -07:00
bitops.h
[FLS64]: generic version
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bug.h
[PATCH] remove all kernel BUGs
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bugs.h
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byteorder.h
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cache.h
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cacheflush.h
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checksum.h
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compiler.h
[PATCH] slab: alpha inlining fix
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console.h
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core_apecs.h
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core_cia.h
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core_marvel.h
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core_mcpcia.h
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core_polaris.h
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core_t2.h
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core_titan.h
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core_tsunami.h
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core_wildfire.h
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cputime.h
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current.h
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delay.h
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div64.h
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dma-mapping.h
[PATCH] alpha: dma_map_page() fix
2006-01-06 08:33:21 -08:00
dma.h
Linux-2.6.12-rc2
2005-04-16 15:20:36 -07:00
elf.h
[PATCH] auxiliary vector cleanups
2005-09-07 16:57:21 -07:00
emergency-restart.h
[PATCH] Add emergency_restart()
2005-07-26 14:35:41 -07:00
err_common.h
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err_ev6.h
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err_ev7.h
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errno.h
[PATCH] add EOWNERDEAD and ENOTRECOVERABLE version 2
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fcntl.h
[PATCH] Clean up struct flock definitions
2005-09-07 16:57:38 -07:00
floppy.h
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fpu.h
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futex.h
[PATCH] Remove unused var from asm/futex.h
2005-09-21 16:16:29 -07:00
gct.h
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gentrap.h
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hardirq.h
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hw_irq.h
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hwrpb.h
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ide.h
[PATCH] ide: move CONFIG_IDE_MAX_HWIFS into linux/ide.h
2005-11-09 22:58:07 +01:00
io.h
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io_trivial.h
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ioctl.h
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ioctls.h
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ipcbuf.h
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irq.h
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jensen.h
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kmap_types.h
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linkage.h
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local.h
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machvec.h
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mc146818rtc.h
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md.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.h
Linux-2.6.12-rc2
2005-04-16 15:20:36 -07:00
mmu_context.h
Linux-2.6.12-rc2
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mmzone.h
[PATCH] remove non-DISCONTIG use of pgdat->node_mem_map
2005-06-23 09:45:00 -07:00
module.h
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msgbuf.h
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namei.h
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numnodes.h
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page.h
[PATCH] mm: consolidate get_order
2005-09-05 00:05:39 -07:00
pal.h
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param.h
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parport.h
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pci.h
[PATCH] Make sparc64 use setup-res.c
2005-09-08 14:57:25 -07:00
percpu.h
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pgalloc.h
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pgtable.h
[PATCH] fix remaining missing includes
2005-11-07 07:53:41 -08:00
poll.h
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posix_types.h
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processor.h
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ptrace.h
[PATCH] consolidate sys_ptrace()
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reg.h
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regdef.h
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resource.h
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rtc.h
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rwsem.h
[PATCH] add sem_is_read/write_locked()
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scatterlist.h
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sections.h
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segment.h
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semaphore.h
[PATCH] semaphore: Remove __MUTEX_INITIALIZER()
2005-10-30 17:37:27 -08:00
sembuf.h
Linux-2.6.12-rc2
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serial.h
[PATCH] Serial: Split 8250 port table (part 2)
2005-06-29 18:45:19 +01:00
setup.h
Linux-2.6.12-rc2
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sfp-machine.h
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shmbuf.h
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shmparam.h
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sigcontext.h
Linux-2.6.12-rc2
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siginfo.h
[PATCH] consolidate SIGEV_PAD_SIZE
2005-05-01 08:59:08 -07:00
signal.h
[PATCH] asm/signal.h unification
2005-05-04 07:33:15 -07:00
smp.h
Revert broken "statement with no effect" warning fix
2005-07-28 10:34:47 -07:00
socket.h
[NET]: Introduce SO_{SND,RCV}BUFFORCE socket options
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sockios.h
Linux-2.6.12-rc2
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spinlock.h
[PATCH] spinlock consolidation
2005-09-10 10:06:21 -07:00
spinlock_types.h
[PATCH] spinlock consolidation
2005-09-10 10:06:21 -07:00
stat.h
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statfs.h
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string.h
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suspend.h
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sysinfo.h
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system.h
[PATCH] alpha: atomic dependency fix
2005-10-25 09:32:46 -07:00
termbits.h
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termios.h
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thread_info.h
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timex.h
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tlb.h
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tlbflush.h
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topology.h
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types.h
[PATCH] sab: consolidate kmem_bufctl_t
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uaccess.h
[PATCH] remove verify_area(): remove verify_area() from various uaccess.h headers
2005-09-07 16:57:35 -07:00
ucontext.h
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unaligned.h
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unistd.h
[PATCH] new alpha syscalls
2005-07-27 18:24:24 -07:00
user.h
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vga.h
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xor.h
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