diff options
Diffstat (limited to 'drivers/staging/ramzswap/ramzswap_drv.h')
| -rw-r--r-- | drivers/staging/ramzswap/ramzswap_drv.h | 171 |
1 files changed, 171 insertions, 0 deletions
diff --git a/drivers/staging/ramzswap/ramzswap_drv.h b/drivers/staging/ramzswap/ramzswap_drv.h new file mode 100644 index 000000000000..a6ea240935b6 --- /dev/null +++ b/drivers/staging/ramzswap/ramzswap_drv.h @@ -0,0 +1,171 @@ +/* + * Compressed RAM based swap device + * + * Copyright (C) 2008, 2009 Nitin Gupta + * + * This code is released using a dual license strategy: BSD/GPL + * You can choose the licence that better fits your requirements. + * + * Released under the terms of 3-clause BSD License + * Released under the terms of GNU General Public License Version 2.0 + * + * Project home: http://compcache.googlecode.com + */ + +#ifndef _RAMZSWAP_DRV_H_ +#define _RAMZSWAP_DRV_H_ + +#include "ramzswap_ioctl.h" +#include "xvmalloc.h" + +/* + * Some arbitrary value. This is just to catch + * invalid value for num_devices module parameter. + */ +static const unsigned max_num_devices = 32; + +/* + * Stored at beginning of each compressed object. + * + * It stores back-reference to table entry which points to this + * object. This is required to support memory defragmentation or + * migrating compressed pages to backing swap disk. + */ +struct zobj_header { +#if 0 + u32 table_idx; +#endif +}; + +/*-- Configurable parameters */ + +/* Default ramzswap disk size: 25% of total RAM */ +static const unsigned default_disksize_perc_ram = 25; +static const unsigned default_memlimit_perc_ram = 15; + +/* + * Max compressed page size when backing device is provided. + * Pages that compress to size greater than this are sent to + * physical swap disk. + */ +static const unsigned max_zpage_size_bdev = PAGE_SIZE / 2; + +/* + * Max compressed page size when there is no backing dev. + * Pages that compress to size greater than this are stored + * uncompressed in memory. + */ +static const unsigned max_zpage_size_nobdev = PAGE_SIZE / 4 * 3; + +/* + * NOTE: max_zpage_size_{bdev,nobdev} sizes must be + * less than or equal to: + * XV_MAX_ALLOC_SIZE - sizeof(struct zobj_header) + * since otherwise xv_malloc would always return failure. + */ + +/*-- End of configurable params */ + +#define SECTOR_SHIFT 9 +#define SECTOR_SIZE (1 << SECTOR_SHIFT) +#define SECTORS_PER_PAGE_SHIFT (PAGE_SHIFT - SECTOR_SHIFT) +#define SECTORS_PER_PAGE (1 << SECTORS_PER_PAGE_SHIFT) + +/* Debugging and Stats */ +#if defined(CONFIG_RAMZSWAP_STATS) +#define stat_inc(stat) ((stat)++) +#define stat_dec(stat) ((stat)--) +#else +#define stat_inc(x) +#define stat_dec(x) +#endif + +/* Flags for ramzswap pages (table[page_no].flags) */ +enum rzs_pageflags { + /* Page is stored uncompressed */ + RZS_UNCOMPRESSED, + + /* Page consists entirely of zeros */ + RZS_ZERO, + + __NR_RZS_PAGEFLAGS, +}; + +/*-- Data structures */ + +/* + * Allocated for each swap slot, indexed by page no. + * These table entries must fit exactly in a page. + */ +struct table { + struct page *page; + u16 offset; + u8 count; /* object ref count (not yet used) */ + u8 flags; +} __attribute__((aligned(4)));; + +/* + * Swap extent information in case backing swap is a regular + * file. These extent entries must fit exactly in a page. + */ +struct ramzswap_backing_extent { + pgoff_t phy_pagenum; + pgoff_t num_pages; +} __attribute__((aligned(4))); + +struct ramzswap_stats { + /* basic stats */ + size_t compr_size; /* compressed size of pages stored - + * needed to enforce memlimit */ + /* more stats */ +#if defined(CONFIG_RAMZSWAP_STATS) + u64 num_reads; /* failed + successful */ + u64 num_writes; /* --do-- */ + u64 failed_reads; /* can happen when memory is too low */ + u64 failed_writes; /* should NEVER! happen */ + u64 invalid_io; /* non-swap I/O requests */ + u32 pages_zero; /* no. of zero filled pages */ + u32 pages_stored; /* no. of pages currently stored */ + u32 good_compress; /* % of pages with compression ratio<=50% */ + u32 pages_expand; /* % of incompressible pages */ + u64 bdev_num_reads; /* no. of reads on backing dev */ + u64 bdev_num_writes; /* no. of writes on backing dev */ +#endif +}; + +struct ramzswap { + struct xv_pool *mem_pool; + void *compress_workmem; + void *compress_buffer; + struct table *table; + struct mutex lock; + struct request_queue *queue; + struct gendisk *disk; + int init_done; + /* + * This is limit on compressed data size (stats.compr_size) + * Its applicable only when backing swap device is present. + */ + size_t memlimit; /* bytes */ + /* + * This is limit on amount of *uncompressed* worth of data + * we can hold. When backing swap device is provided, it is + * set equal to device size. + */ + size_t disksize; /* bytes */ + + struct ramzswap_stats stats; + + /* backing swap device info */ + struct ramzswap_backing_extent *curr_extent; + struct list_head backing_swap_extent_list; + unsigned long num_extents; + char backing_swap_name[MAX_SWAP_NAME_LEN]; + struct block_device *backing_swap; + struct file *swap_file; +}; + +/*-- */ + +#endif + |