Commit Graph

18 Commits

Author SHA1 Message Date
Nitin Gupta
107c161b7d Staging: ramzswap: Handler for swap slot free callback
Install handler for swap_slot_free_notify callback which is called
when a swap slot is no longer used. This handler immediately frees
memory allocated corresponding to the given swap slot.

Signed-off-by: Nitin Gupta <ngupta@vflare.org>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Acked-by: Nigel Cunningham <nigel@tuxonice.net>
Acked-by: Pekka Enberg <penberg@cs.helsinki.fi>
Reviewed-by: Minchan Kim <minchan.kim@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2010-05-18 15:07:52 -07:00
Nitin Gupta
97a0638218 Staging: ramzswap: Remove backing swap support
Currently, each ramzswap device can be assigned
a separate 'backing swap' file/partition. The ramzswap
driver forwards swap I/O requests to this backing swap
whenever an incompressible page is found.

This feature adds nearly 700 lines of code and it
also duplicates much of the swapon() functionality
(for example, finding swap extents and so on). Removing
this code makes the driver much simpler and should
help its transition from staging to stable drivers
area (drivers/block/).

Similar functionality may be implemented if we can
implement migrating pages across swap devices but the
details have not yet been worked out.

Support for _partitions_ as backing swap could be
retained as it requires a few lines of code only.
This part can be re-introduced later if above swap
migration method turns out to be infeasible.

More cleanups and code comments will be added soon.

Signed-off-by: Nitin Gupta <ngupta@vflare.org>
Acked-by: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2010-05-14 13:25:28 -07:00
Tejun Heo
5a0e3ad6af include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h
percpu.h is included by sched.h and module.h and thus ends up being
included when building most .c files.  percpu.h includes slab.h which
in turn includes gfp.h making everything defined by the two files
universally available and complicating inclusion dependencies.

percpu.h -> slab.h dependency is about to be removed.  Prepare for
this change by updating users of gfp and slab facilities include those
headers directly instead of assuming availability.  As this conversion
needs to touch large number of source files, the following script is
used as the basis of conversion.

  http://userweb.kernel.org/~tj/misc/slabh-sweep.py

The script does the followings.

* Scan files for gfp and slab usages and update includes such that
  only the necessary includes are there.  ie. if only gfp is used,
  gfp.h, if slab is used, slab.h.

* When the script inserts a new include, it looks at the include
  blocks and try to put the new include such that its order conforms
  to its surrounding.  It's put in the include block which contains
  core kernel includes, in the same order that the rest are ordered -
  alphabetical, Christmas tree, rev-Xmas-tree or at the end if there
  doesn't seem to be any matching order.

* If the script can't find a place to put a new include (mostly
  because the file doesn't have fitting include block), it prints out
  an error message indicating which .h file needs to be added to the
  file.

The conversion was done in the following steps.

1. The initial automatic conversion of all .c files updated slightly
   over 4000 files, deleting around 700 includes and adding ~480 gfp.h
   and ~3000 slab.h inclusions.  The script emitted errors for ~400
   files.

2. Each error was manually checked.  Some didn't need the inclusion,
   some needed manual addition while adding it to implementation .h or
   embedding .c file was more appropriate for others.  This step added
   inclusions to around 150 files.

3. The script was run again and the output was compared to the edits
   from #2 to make sure no file was left behind.

4. Several build tests were done and a couple of problems were fixed.
   e.g. lib/decompress_*.c used malloc/free() wrappers around slab
   APIs requiring slab.h to be added manually.

5. The script was run on all .h files but without automatically
   editing them as sprinkling gfp.h and slab.h inclusions around .h
   files could easily lead to inclusion dependency hell.  Most gfp.h
   inclusion directives were ignored as stuff from gfp.h was usually
   wildly available and often used in preprocessor macros.  Each
   slab.h inclusion directive was examined and added manually as
   necessary.

6. percpu.h was updated not to include slab.h.

7. Build test were done on the following configurations and failures
   were fixed.  CONFIG_GCOV_KERNEL was turned off for all tests (as my
   distributed build env didn't work with gcov compiles) and a few
   more options had to be turned off depending on archs to make things
   build (like ipr on powerpc/64 which failed due to missing writeq).

   * x86 and x86_64 UP and SMP allmodconfig and a custom test config.
   * powerpc and powerpc64 SMP allmodconfig
   * sparc and sparc64 SMP allmodconfig
   * ia64 SMP allmodconfig
   * s390 SMP allmodconfig
   * alpha SMP allmodconfig
   * um on x86_64 SMP allmodconfig

8. percpu.h modifications were reverted so that it could be applied as
   a separate patch and serve as bisection point.

Given the fact that I had only a couple of failures from tests on step
6, I'm fairly confident about the coverage of this conversion patch.
If there is a breakage, it's likely to be something in one of the arch
headers which should be easily discoverable easily on most builds of
the specific arch.

Signed-off-by: Tejun Heo <tj@kernel.org>
Guess-its-ok-by: Christoph Lameter <cl@linux-foundation.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
2010-03-30 22:02:32 +09:00
Nitin Gupta
1130ebbaae Staging: ramzswap: Update copyright notice
Update copyright notice.

Signed-off-by: Nitin Gupta <ngupta@vflare.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2010-03-03 16:42:53 -08:00
Nitin Gupta
c25d75a234 Staging: ramzswap: Handle case for invalid backing swap
Currently, we crash (issue BUG_ON) if backing swap
disk size is zero. This can happen is user specified
an extended partition or simply a bad disk as backing
swap. A crash is really an unpleasant surprise to user
for such trivial problems.

Now, we check for this condition and simply fail device
initialization if this is the case.

Additional cleanups:
 * use static for all functions
 * remove extra newline between functions
 * memset backing_swap_name to NULL on device reset

Signed-off-by: Nitin Gupta <ngupta@vflare.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2010-03-03 16:42:53 -08:00
Nitin Gupta
2e88228174 Staging: ramzswap: Remove redundant check for zero page
ramzswap_free_page() already handles the case for zero filled
pages. So, remove redundant logic for the same in ramzswap_write().

Signed-off-by: Nitin Gupta <ngupta@vflare.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2010-03-03 16:42:53 -08:00
Nitin Gupta
de1a21a0f1 Staging: ramzswap: Return proper error code on device create failure
Currently, we return 0 if create_device() fails and 1 otherwise.
Now, proper error code is returned from create_device() and the
same is propagated as module error code from ramzswap_init().

Also added some cleanups for ramzswap_init(), improving function
structure.

Signed-off-by: Nitin Gupta <ngupta@vflare.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2010-03-03 16:42:53 -08:00
Nitin Gupta
5d83d5a0b5 Staging: ramzswap: Set block size to PAGE_SIZE
ramzswap block size needs to be set equal to PAGE_SIZE to
avoid receiving any unaligned block I/O requests (happens
due to readahead logic during swapon). These unaligned
accesses produce unnecessary I/O errors, scaring users.

Signed-off-by: Nitin Gupta <ngupta@vflare.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2010-03-03 16:42:53 -08:00
Nitin Gupta
7eef753390 Staging: ramzswap: Flush block device before reset
Make sure we flush block device before freeing all metadata
during reset ioctl.

Signed-off-by: Nitin Gupta <ngupta@vflar.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2010-03-03 16:42:53 -08:00
Nitin Gupta
6a90772886 Staging: ramzswap: Use lock for 64-bit stats
64-bit stats corruption was observed when ramzswap was
used on SMP systems. To prevent this, use separate spinlock
to protect these stats.

Also, replace stat_*() with rzs_stat*() to avoid possible
conflict with core kernel code.

Eventually, these will be converted to per-cpu counters
if this driver finds use on large scale systems and this
locking is found to affect scalability.

Signed-off-by: Nitin Gupta <ngupta@vflare.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2010-03-03 16:42:53 -08:00
Minchan Kim
3bf040c752 Staging: ramzswap: Free memory when create_device is failed
If create_device is failed, it can't free gendisk and request_queue of
preceding devices. It cause memory leak.

This patch fixes it.

Signed-off-by: Minchan Kim <minchan.kim@gmail.com>
Acked-by: Nitin Gupta <ngupta@vflare.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2010-03-03 16:42:42 -08:00
C yp
ef4ffb7ade Staging: ramzswap: Minor spelling fixes
Also removed an extra semicolon.

Signed-off-by: Cyp <cyp561@gmail.com>
Cc: Nitin Gupta <ngupta@vflare.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2010-03-03 16:42:38 -08:00
Huang Weiyi
f70615a8f1 Staging: ramzswap: remove unused #include <linux/version.h>
Remove unused #include <linux/version.h>('s) in
  drivers/staging/ramzswap/ramzswap_drv.c

Signed-off-by: Huang Weiyi <weiyi.huang@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2010-03-03 16:42:30 -08:00
Nitin Gupta
30fb8a7141 Staging: ramzswap: remove ARM specific d-cache hack
Remove d-cache hack in ramzswap driver that was needed
to workaround a bug in ARM version of update_mmu_cache()
which caused stale data in d-cache to be transferred to
userspace. This bug was fixed by git commit:
	787b2faadc
This also brings down one entry in TODO file.

Signed-off-by: Nitin Gupta <ngupta@vflare.org>
Acked-by: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2009-12-23 11:27:49 -08:00
Nitin Gupta
224f0ef4e2 Staging: ramzswap: add TODO file
TODO file for ramzswap.

Signed-off-by: Nitin Gupta <ngupta@vflare.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2009-12-11 12:23:04 -08:00
Nitin Gupta
47f9afb38f Staging: ramzswap: documentation
Short guide on how to setup and use ramzswap.

Signed-off-by: Nitin Gupta <ngupta@vflare.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2009-12-11 12:23:04 -08:00
Nitin Gupta
306b0c957f Staging: virtual block device driver (ramzswap)
Creates RAM based block devices (/dev/ramzswapX) which can be
used (only) as swap disks. Pages swapped to these are compressed
and stored in memory itself.

The module is called ramzswap.ko. It depends on:
 - xvmalloc memory allocator (compiled with this driver)
 - lzo_compress.ko
 - lzo_decompress.ko

See ramzswap.txt for usage details.

Signed-off-by: Nitin Gupta <ngupta@vflare.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2009-12-11 12:23:04 -08:00
Nitin Gupta
644bf7b598 Staging: xvmalloc memory allocator
* Features:
 - Low metadata overhead (just 4 bytes per object)
 - O(1) Alloc/Free - except when we have to call system page allocator to
   get additional memory.
 - Very low fragmentation: In all tests, xvmalloc memory usage is within 12%
   of "Ideal".
 - Pool based allocator: Each pool can grow and shrink.
 - It maps pages only when required. So, it does not hog vmalloc area which
   is very small on 32-bit systems.

SLUB allocator could not be used due to fragmentation issues:
http://code.google.com/p/compcache/wiki/AllocatorsComparison
Data here shows kmalloc using ~43% more memory than TLSF and xvMalloc
is showed ~2% more space efficiency than TLSF (due to smaller metadata).
Creating various kmem_caches can reduce space efficiency gap but still
problem of being limited to low memory exists. Also, it depends on
allocating higher order pages to reduce fragmentation - this is not
acceptable for ramzswap as it is used under memory crunch (its a swap
device!).

SLOB allocator could not be used do to reasons mentioned here:
http://lkml.org/lkml/2009/3/18/210

* Implementation:
It uses two-level bitmap search to find free list containing block of
correct size. This idea is taken from TLSF (Two-Level Segregate Fit)
allocator and is well explained in its paper (see [Links] below).

* Limitations:
 - Poor scalability: No per-cpu data structures (work in progress).

[Links]
1. Details and Performance data:
http://code.google.com/p/compcache/wiki/xvMalloc
http://code.google.com/p/compcache/wiki/xvMallocPerformance

2. TLSF memory allocator:
home: http://rtportal.upv.es/rtmalloc/
paper: http://rtportal.upv.es/rtmalloc/files/MRBC_2008.pdf

Signed-off-by: Nitin Gupta <ngupta@vflare.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2009-12-11 12:23:04 -08:00