[PATCH 0/3] compressed in-memory swapping take3

[Nitin Gupta]

Hi,

Project home: http://code.google.com/p/compcache/

It allows creating a RAM based block device which acts as swap disk.
Pages swapped to this device are compressed and stored in memory itself.
This is a big win over swapping to slow hard-disk which are typically used
as swap disk. For flash, these suffer from wear-leveling issues when used
as swap disk - so again its helpful. For swapless systems, it allows more
apps to run.


* Changelog: take3 vs take2
xvmalloc changes:
 - Use kernel defined macros and constants in xvmalloc and remove
   equivalent defines for ALIGN, roundup etc.
 - Use kernel bitops (set_bit, clear_bit)
 - Moved it to drivers/block since its not clear if it has any other
   user.
ramzswap changes:
 - All instances of compcache renamed to ramzswap.
   Also renamed module to ramzswap
 - Renamed "backing_dev" parameter to "backing_swap"
 - Documentation changes to reflect above changes.
 - Remove "table index" from object header (4 bytes). This will be
   needed when memory defragmentation is implemented. So, avoid this
   (small) overhead for now.


* Changelog: take2 vs initial revision:
xvmalloc changes:
 - Use Linux kernel coding style for xvmalloc
 - Collapse all individual flag test/set/get to generic {test_set_get}_flag
 - Added BLOCK_NEXT() macro to reach next contiguous block
 - Other minor cleanups - no functional changes
compcache block device code:
 - compcache core changes due to change in xvmalloc interface names


Links to performance numbers, use cases can be found in original thread:
http://lkml.org/lkml/2009/3/17/116

Thanks to Christoph, Pekka and Andrew for feedback on previous revisions.

Thanks,
Nitin
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