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Improved the performance of the garbage collector and the algorithm for

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finding contiguous pages.

Adjusted the file header and added a validity indicator.

Removed some redundant code and fixes minor issues in the text.
This commit is contained in:
nvt-se 2008-08-15 12:34:56 +00:00
parent deefb97c16
commit c36a0a33fc
1 changed files with 30 additions and 29 deletions
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53
core/cfs/cfs-coffee.c
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@ -32,7 +32,7 @@
/**
* \file
* Coffee: A flash file system on memory-contrained sensor systems.
* Coffee: A flash file system for memory-contrained sensor systems.
* \author
* Nicolas Tsiftes <nvt@sics.se>
*/
@ -64,10 +64,11 @@
#define COFFEE_PAGE_COUNT (COFFEE_SIZE / COFFEE_PAGE_SIZE)
#define COFFEE_PAGES_PER_SECTOR (COFFEE_SECTOR_SIZE / COFFEE_PAGE_SIZE)
#define COFFEE_FLAG_ALLOCATED 0x1
#define COFFEE_FLAG_OBSOLETE 0x2
#define COFFEE_FLAG_MODIFIED 0x4
#define COFFEE_FLAG_LOG 0x8
#define COFFEE_FLAG_VALID 0x1
#define COFFEE_FLAG_ALLOCATED 0x2
#define COFFEE_FLAG_OBSOLETE 0x4
#define COFFEE_FLAG_MODIFIED 0x8
#define COFFEE_FLAG_LOG 0x10
#define LOG_CMD_MAGIC 0x7a
@ -95,9 +96,9 @@ struct file_desc {
uint32_t offset;
uint32_t end;
uint16_t file_page;
uint8_t flags;
uint16_t max_pages;
uint16_t next_log_entry;
uint8_t flags;
};
struct dir_cache {
@ -106,12 +107,12 @@ struct dir_cache {
};
struct file_header {
unsigned flags:4;
unsigned max_pages:12;
unsigned log_page:16;
unsigned eof_locator:16;
unsigned log_entries:16;
unsigned log_entry_size:16;
uint16_t log_page;
uint16_t log_entries;
uint16_t log_entry_size;
uint16_t max_pages;
uint8_t eof_hint;
uint8_t flags;
char name[COFFEE_NAME_LENGTH];
} __attribute__((packed));
@ -136,7 +137,7 @@ get_sector_status(uint16_t sector, uint16_t *active,
uint32_t offset;
uint32_t end;
struct file_header hdr;
static uint16_t skip_pages;
static int16_t skip_pages;
static int last_pages_are_active;
*active = *free = *obsolete = 0;
@ -164,25 +165,25 @@ get_sector_status(uint16_t sector, uint16_t *active,
while(offset < end) {
COFFEE_READ(&hdr, sizeof (hdr), offset);
if(COFFEE_PAGE_ACTIVE(hdr)) {
offset += hdr.max_pages * COFFEE_PAGE_SIZE;
last_pages_are_active = 1;
offset += hdr.max_pages * COFFEE_PAGE_SIZE;
*active += hdr.max_pages;
} else if(COFFEE_PAGE_OBSOLETE(hdr)) {
last_pages_are_active = 0;
offset += hdr.max_pages * COFFEE_PAGE_SIZE;
*obsolete += hdr.max_pages;
} else if(COFFEE_PAGE_FREE(hdr)) {
++*free;
offset += COFFEE_PAGE_SIZE;
*free = (end - offset) / COFFEE_PAGE_SIZE;
break;
}
}
skip_pages = *active + *free + *obsolete - COFFEE_PAGES_PER_SECTOR;
skip_pages = *active + *obsolete - COFFEE_PAGES_PER_SECTOR;
if(skip_pages > 0) {
if(last_pages_are_active) {
*active = COFFEE_PAGES_PER_SECTOR - *free - *obsolete;
*active = COFFEE_PAGES_PER_SECTOR - *obsolete;
} else {
*obsolete = COFFEE_PAGES_PER_SECTOR - *free - *active;
*obsolete = COFFEE_PAGES_PER_SECTOR - *active;
}
}
}
@ -258,8 +259,8 @@ find_file(const char *name)
page += hdr.max_pages;
} else {
/* It follows from the properties of the page allocation algorithm
that if a free page is encountered, the rest of the sector is
also free. */
that if a free page is encountered, then the rest of the sector
is also free. */
page = (page + COFFEE_PAGES_PER_SECTOR) & ~(COFFEE_PAGES_PER_SECTOR - 1);
}
watchdog_periodic();
@ -282,10 +283,10 @@ find_offset_in_file(int first_page)
* Move from the end of the file towards the beginning and look for
* a byte that has been modified.
*
* One important implication of this is that if the last written bytes
* An important implication of this is that if the last written bytes
* are zeroes, then these are skipped from the calculation.
*
*/
for(page = first_page + hdr.max_pages - 1; page >= first_page; page--) {
watchdog_periodic();
COFFEE_READ(buf, sizeof (buf), page * COFFEE_PAGE_SIZE);
@ -321,7 +322,7 @@ find_contiguous_pages(unsigned wanted)
return start;
}
}
page++;
page = (page + COFFEE_PAGES_PER_SECTOR) & ~(COFFEE_PAGES_PER_SECTOR - 1);
} else {
start = -1;
page += hdr.max_pages;
@ -959,9 +960,9 @@ cfs_coffee_reserve(const char *name, uint32_t size)
memcpy(hdr.name, name, sizeof (hdr.name));
hdr.name[sizeof (hdr.name) - 1] = '\0';
hdr.max_pages = need_pages;
hdr.flags = COFFEE_FLAG_ALLOCATED;
hdr.flags = COFFEE_FLAG_ALLOCATED | COFFEE_FLAG_VALID;
hdr.log_page = 0;
hdr.eof_locator = 0;
hdr.eof_hint = 0;
hdr.log_entries = 0;
hdr.log_entry_size = 0;
WRITE_HEADER(&hdr, page);