From c36a0a33fc143ba9a0c2c3bd1978406af5afc358 Mon Sep 17 00:00:00 2001
From: nvt-se <nvt-se>
Date: Fri, 15 Aug 2008 12:34:56 +0000
Subject: [PATCH] Improved the performance of the garbage collector and the
algorithm for finding contiguous pages.
Adjusted the file header and added a validity indicator.
Removed some redundant code and fixes minor issues in the text.
---
core/cfs/cfs-coffee.c | 59 ++++++++++++++++++++++---------------------
1 file changed, 30 insertions(+), 29 deletions(-)
diff --git a/core/cfs/cfs-coffee.c b/core/cfs/cfs-coffee.c
index fbb3effe9..d2f64c7e1 100644
--- a/core/cfs/cfs-coffee.c
+++ b/core/cfs/cfs-coffee.c
@@ -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();
@@ -278,14 +279,14 @@ find_offset_in_file(int first_page)
READ_HEADER(&hdr, 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;
@@ -955,13 +956,13 @@ cfs_coffee_reserve(const char *name, uint32_t size)
return -1;
}
}
-
+
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);