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>
This commit is contained in:
Nitin Gupta
Greg Kroah-Hartman
parent
644bf7b598
commit
306b0c957f
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@ -123,6 +123,8 @@ source "drivers/staging/sep/Kconfig"
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source "drivers/staging/iio/Kconfig"
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source "drivers/staging/ramzswap/Kconfig"
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source "drivers/staging/strip/Kconfig"
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source "drivers/staging/arlan/Kconfig"
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@ -43,6 +43,7 @@ obj-$(CONFIG_VME_BUS) += vme/
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obj-$(CONFIG_RAR_REGISTER) += rar/
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obj-$(CONFIG_DX_SEP) += sep/
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obj-$(CONFIG_IIO) += iio/
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obj-$(CONFIG_RAMZSWAP) += ramzswap/
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obj-$(CONFIG_STRIP) += strip/
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obj-$(CONFIG_ARLAN) += arlan/
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obj-$(CONFIG_WAVELAN) += wavelan/
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@ -0,0 +1,21 @@
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config RAMZSWAP
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tristate "Compressed in-memory swap device (ramzswap)"
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depends on SWAP
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select LZO_COMPRESS
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select LZO_DECOMPRESS
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default n
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help
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Creates virtual block devices which can be used (only) as a swap
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disks. Pages swapped to these disks are compressed and stored in
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memory itself.
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See ramzswap.txt for more information.
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Project home: http://compcache.googlecode.com/
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config RAMZSWAP_STATS
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bool "Enable ramzswap stats"
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depends on RAMZSWAP
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default y
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help
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Enable statistics collection for ramzswap. This adds only a minimal
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overhead. In unsure, say Y.
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@ -0,0 +1,3 @@
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ramzswap-objs := ramzswap_drv.o xvmalloc.o
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obj-$(CONFIG_RAMZSWAP) += ramzswap.o
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File diff suppressed because it is too large
Load Diff
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@ -0,0 +1,171 @@
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/*
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* Compressed RAM based swap device
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*
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* Copyright (C) 2008, 2009 Nitin Gupta
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*
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* This code is released using a dual license strategy: BSD/GPL
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* You can choose the licence that better fits your requirements.
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*
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* Released under the terms of 3-clause BSD License
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* Released under the terms of GNU General Public License Version 2.0
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*
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* Project home: http://compcache.googlecode.com
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*/
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#ifndef _RAMZSWAP_DRV_H_
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#define _RAMZSWAP_DRV_H_
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#include "ramzswap_ioctl.h"
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#include "xvmalloc.h"
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/*
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* Some arbitrary value. This is just to catch
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* invalid value for num_devices module parameter.
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*/
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static const unsigned max_num_devices = 32;
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/*
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* Stored at beginning of each compressed object.
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*
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* It stores back-reference to table entry which points to this
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* object. This is required to support memory defragmentation or
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* migrating compressed pages to backing swap disk.
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*/
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struct zobj_header {
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#if 0
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u32 table_idx;
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#endif
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};
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/*-- Configurable parameters */
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/* Default ramzswap disk size: 25% of total RAM */
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static const unsigned default_disksize_perc_ram = 25;
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static const unsigned default_memlimit_perc_ram = 15;
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/*
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* Max compressed page size when backing device is provided.
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* Pages that compress to size greater than this are sent to
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* physical swap disk.
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*/
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static const unsigned max_zpage_size_bdev = PAGE_SIZE / 2;
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/*
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* Max compressed page size when there is no backing dev.
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* Pages that compress to size greater than this are stored
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* uncompressed in memory.
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*/
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static const unsigned max_zpage_size_nobdev = PAGE_SIZE / 4 * 3;
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/*
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* NOTE: max_zpage_size_{bdev,nobdev} sizes must be
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* less than or equal to:
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* XV_MAX_ALLOC_SIZE - sizeof(struct zobj_header)
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* since otherwise xv_malloc would always return failure.
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*/
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/*-- End of configurable params */
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#define SECTOR_SHIFT 9
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#define SECTOR_SIZE (1 << SECTOR_SHIFT)
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#define SECTORS_PER_PAGE_SHIFT (PAGE_SHIFT - SECTOR_SHIFT)
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#define SECTORS_PER_PAGE (1 << SECTORS_PER_PAGE_SHIFT)
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/* Debugging and Stats */
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#if defined(CONFIG_RAMZSWAP_STATS)
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#define stat_inc(stat) ((stat)++)
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#define stat_dec(stat) ((stat)--)
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#else
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#define stat_inc(x)
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#define stat_dec(x)
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#endif
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/* Flags for ramzswap pages (table[page_no].flags) */
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enum rzs_pageflags {
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/* Page is stored uncompressed */
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RZS_UNCOMPRESSED,
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/* Page consists entirely of zeros */
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RZS_ZERO,
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__NR_RZS_PAGEFLAGS,
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};
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/*-- Data structures */
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/*
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* Allocated for each swap slot, indexed by page no.
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* These table entries must fit exactly in a page.
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*/
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struct table {
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struct page *page;
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u16 offset;
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u8 count; /* object ref count (not yet used) */
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u8 flags;
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} __attribute__((aligned(4)));;
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/*
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* Swap extent information in case backing swap is a regular
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* file. These extent entries must fit exactly in a page.
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*/
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struct ramzswap_backing_extent {
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pgoff_t phy_pagenum;
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pgoff_t num_pages;
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} __attribute__((aligned(4)));
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struct ramzswap_stats {
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/* basic stats */
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size_t compr_size; /* compressed size of pages stored -
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* needed to enforce memlimit */
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/* more stats */
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#if defined(CONFIG_RAMZSWAP_STATS)
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u64 num_reads; /* failed + successful */
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u64 num_writes; /* --do-- */
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u64 failed_reads; /* can happen when memory is too low */
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u64 failed_writes; /* should NEVER! happen */
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u64 invalid_io; /* non-swap I/O requests */
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u32 pages_zero; /* no. of zero filled pages */
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u32 pages_stored; /* no. of pages currently stored */
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u32 good_compress; /* % of pages with compression ratio<=50% */
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u32 pages_expand; /* % of incompressible pages */
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u64 bdev_num_reads; /* no. of reads on backing dev */
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u64 bdev_num_writes; /* no. of writes on backing dev */
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#endif
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};
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struct ramzswap {
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struct xv_pool *mem_pool;
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void *compress_workmem;
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void *compress_buffer;
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struct table *table;
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struct mutex lock;
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struct request_queue *queue;
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struct gendisk *disk;
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int init_done;
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/*
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* This is limit on compressed data size (stats.compr_size)
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* Its applicable only when backing swap device is present.
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*/
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size_t memlimit; /* bytes */
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/*
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* This is limit on amount of *uncompressed* worth of data
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* we can hold. When backing swap device is provided, it is
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* set equal to device size.
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*/
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size_t disksize; /* bytes */
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struct ramzswap_stats stats;
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/* backing swap device info */
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struct ramzswap_backing_extent *curr_extent;
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struct list_head backing_swap_extent_list;
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unsigned long num_extents;
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char backing_swap_name[MAX_SWAP_NAME_LEN];
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struct block_device *backing_swap;
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struct file *swap_file;
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};
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/*-- */
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#endif
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@ -0,0 +1,49 @@
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/*
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* Compressed RAM based swap device
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*
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* Copyright (C) 2008, 2009 Nitin Gupta
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*
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* This code is released using a dual license strategy: BSD/GPL
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* You can choose the licence that better fits your requirements.
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*
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* Released under the terms of 3-clause BSD License
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* Released under the terms of GNU General Public License Version 2.0
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*
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* Project home: http://compcache.googlecode.com
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*/
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#ifndef _RAMZSWAP_IOCTL_H_
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#define _RAMZSWAP_IOCTL_H_
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#define MAX_SWAP_NAME_LEN 128
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struct ramzswap_ioctl_stats {
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char backing_swap_name[MAX_SWAP_NAME_LEN];
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u64 memlimit; /* only applicable if backing swap present */
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u64 disksize; /* user specified or equal to backing swap
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* size (if present) */
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u64 num_reads; /* failed + successful */
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u64 num_writes; /* --do-- */
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u64 failed_reads; /* can happen when memory is too low */
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u64 failed_writes; /* should NEVER! happen */
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u64 invalid_io; /* non-swap I/O requests */
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u32 pages_zero; /* no. of zero filled pages */
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u32 good_compress_pct; /* no. of pages with compression ratio<=50% */
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u32 pages_expand_pct; /* no. of incompressible pages */
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u32 pages_stored;
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u32 pages_used;
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u64 orig_data_size;
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u64 compr_data_size;
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u64 mem_used_total;
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u64 bdev_num_reads; /* no. of reads on backing dev */
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u64 bdev_num_writes; /* no. of writes on backing dev */
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} __attribute__ ((packed, aligned(4)));
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#define RZSIO_SET_DISKSIZE_KB _IOW('z', 0, size_t)
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#define RZSIO_SET_MEMLIMIT_KB _IOW('z', 1, size_t)
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#define RZSIO_SET_BACKING_SWAP _IOW('z', 2, unsigned char[MAX_SWAP_NAME_LEN])
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#define RZSIO_GET_STATS _IOR('z', 3, struct ramzswap_ioctl_stats)
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#define RZSIO_INIT _IO('z', 4)
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#define RZSIO_RESET _IO('z', 5)
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#endif
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