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Date: Wed, 17 Aug 2011 16:47:16 +0900
From: Kazuya Mio <k-mio@...jp.nec.com>
To: ext4 <linux-ext4@...r.kernel.org>, Theodore Tso <tytso@....edu>
Subject: [PATCH v2 04/12] e4defrag: Use e2p_get_fragscore() for decision of
whether to defrag
This makes e4defrag use e2p_get_fragscore() to calculate fragmentation score.
If the fragmentation score of the original file is non-zero and
the fragmentation score of donor file is zero, e4defrag calls
EXT4_IOC_MOVE_EXT ioctl. Because the fragmentation will get better in this case.
e4defrag uses 4096 as the threshold of fragmentation because the bigger
threshold(<4096) has little effect on the performance from the following
results of my experiment.
METHOD
---
1) Created 4GB fragmented file in 16GB ext4 filesystem. The length of
all extents in the created file was the same, and the physical block of
each extents was allocated at random.
For examples, when the length of all extents is 512 blocks, filefrag shows
the following extent information:
#filefrag -v /mnt/mp1/fragment
Filesystem type is: ef53
File size of /mnt/mp1/fragment is 4294967296 (1048576 blocks, blocksize 4096)
ext logical physical expected length flags
0 0 1852416 512
1 512 1584672 1852927 512
2 1024 644608 1585183 512
3 1536 3760128 645119 511
4 2048 3389952 3760638 512
<snip>
2057 1046016 1066016 3930111 512
2058 1046528 559104 1066527 512
2059 1047040 680960 559615 512
2060 1047552 1175552 681471 512
2061 1048064 2780672 1176063 512 eof
/mnt/mp1/fragment: 2062 extents found
2) Read the file by cat command three times, and calculated the average of
the read time.
RESULT
---
The following table is its result. It shows that read time is about the same
when the length of the extents is bigger than 4096.
ext length | ext num | time (s)
---------------------------------
32768 | 37 | 85.94
16384 | 67 | 85.61
8192 | 131 | 86.60
4096 | 260 | 88.87
2048 | 519 | 95.31
1024 | 1031 | 105.96
512 | 2052 | 124.32
256 | 4120 | 160.44
128 | 8242 | 226.28
Signed-off-by: Kazuya Mio <k-mio@...jp.nec.com>
---
misc/Makefile.in | 4 +--
misc/e4defrag.c | 64 ++++++++++++++++++++++++++++++++++++++++++++++++++-----
2 files changed, 61 insertions(+), 7 deletions(-)
diff --git a/misc/Makefile.in b/misc/Makefile.in
index 5f62323..d5dfdf8 100644
--- a/misc/Makefile.in
+++ b/misc/Makefile.in
@@ -196,9 +196,9 @@ e2undo.profiled: $(PROFILED_E2UNDO_OBJS) $(PROFILED_DEPLIBS)
$(Q) $(CC) $(ALL_LDFLAGS) -g -pg -o e2undo.profiled \
$(PROFILED_E2UNDO_OBJS) $(PROFILED_LIBS) $(LIBINTL)
-e4defrag: $(E4DEFRAG_OBJS) $(DEPLIBS)
+e4defrag: $(E4DEFRAG_OBJS) $(DEPLIBS) $(DEPLIBS_E2P)
$(E) " LD $@"
- $(Q) $(CC) $(ALL_LDFLAGS) -o e4defrag $(E4DEFRAG_OBJS) $(LIBS)
+ $(Q) $(CC) $(ALL_LDFLAGS) -o e4defrag $(E4DEFRAG_OBJS) $(LIBS) $(LIBE2P)
e4defrag.profiled: $(PROFILED_E4DEFRAG_OBJS) $(PROFILED_DEPLIBS)
$(E) " LD $@"
diff --git a/misc/e4defrag.c b/misc/e4defrag.c
index 58fd9be..44d54f3 100644
--- a/misc/e4defrag.c
+++ b/misc/e4defrag.c
@@ -31,16 +31,18 @@
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
-#include <ext2fs/ext2_types.h>
#include <linux/fs.h>
#include <sys/ioctl.h>
-#include <ext2fs/fiemap.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <sys/statfs.h>
#include <sys/syscall.h>
#include <sys/vfs.h>
+#include "e2p/e2p.h"
+#include "ext2fs/ext2_types.h"
+#include "ext2fs/fiemap.h"
+
/* A relatively new ioctl interface ... */
#ifndef EXT4_IOC_MOVE_EXT
#define EXT4_IOC_MOVE_EXT _IOWR('f', 15, struct move_extent)
@@ -97,6 +99,12 @@
*/
#define EXTENT_MAX_COUNT 512
+/* Preferred number of blocks in one extent */
+#define DEFAULT_THRESHOLD 4096
+
+/* Maximum number of blocks in one extent */
+#define EXTENT_MAX_BLKS 32768
+
/* The following macros are error message */
#define MSG_USAGE \
"Usage : e4defrag [-v] file...| directory...| device...\n"
@@ -145,6 +153,7 @@ int block_size;
int extents_before_defrag;
int extents_after_defrag;
int mode_flag;
+unsigned int threshold;
unsigned int current_uid;
unsigned int defraged_file_count;
unsigned int frag_files_before_defrag;
@@ -962,8 +971,10 @@ static int file_defrag(const char *file, const struct stat64 *buf,
int fd;
int donor_fd = -1;
int ret;
+ int err = 0;
int file_frags_start, file_frags_end;
char tmp_inode_name[PATH_MAX + 8];
+ unsigned int orig_score = 0, donor_score = 0;
ext4_fsblk_t blk_count = 0;
struct fiemap_extent_list *orig_list = NULL;
struct fiemap_extent_list *donor_list = NULL;
@@ -1046,9 +1057,9 @@ static int file_defrag(const char *file, const struct stat64 *buf,
goto out;
}
- /* Combine extents to group */
- ret = join_extents(orig_list, &orig_group_head);
- if (ret < 0) {
+ orig_score = e2p_get_fragscore(fd, threshold, EXTENT_MAX_BLKS, &err);
+ if (err) {
+ errno = err;
if (mode_flag & DETAIL) {
PRINT_FILE_NAME(file);
PRINT_ERR_MSG_WITH_ERRNO(NGMSG_FILE_EXTENT);
@@ -1056,6 +1067,9 @@ static int file_defrag(const char *file, const struct stat64 *buf,
goto out;
}
+ if (!orig_score)
+ goto check_improvement;
+
/* Create donor inode */
memset(tmp_inode_name, 0, PATH_MAX + 8);
sprintf(tmp_inode_name, "%.*s.defrag",
@@ -1083,6 +1097,16 @@ static int file_defrag(const char *file, const struct stat64 *buf,
goto out;
}
+ /* Combine extents to group */
+ ret = join_extents(orig_list, &orig_group_head);
+ if (ret < 0) {
+ if (mode_flag & DETAIL) {
+ PRINT_FILE_NAME(file);
+ PRINT_ERR_MSG_WITH_ERRNO("Failed to allocate memory");
+ }
+ goto out;
+ }
+
/* Allocate space for donor inode */
orig_group_tmp = orig_group_head;
do {
@@ -1110,6 +1134,18 @@ static int file_defrag(const char *file, const struct stat64 *buf,
goto out;
}
+ donor_score = e2p_get_fragscore(donor_fd, threshold,
+ EXTENT_MAX_BLKS, &err);
+ if (err) {
+ errno = err;
+ if (mode_flag & DETAIL) {
+ PRINT_FILE_NAME(file);
+ PRINT_ERR_MSG_WITH_ERRNO(NGMSG_FILE_EXTENT);
+ }
+ goto out;
+ }
+
+check_improvement:
if (mode_flag & DETAIL) {
if (file_frags_start != 1)
frag_files_before_defrag++;
@@ -1117,6 +1153,23 @@ static int file_defrag(const char *file, const struct stat64 *buf,
extents_before_defrag += file_frags_start;
}
+ if (!orig_score || donor_score) {
+ printf("\033[79;0H\033[K[%u/%u]%s:\t%3d%%",
+ defraged_file_count, total_count, file, 100);
+ if (mode_flag & DETAIL)
+ printf(" extents: %d -> %d",
+ file_frags_start, file_frags_start);
+
+ printf("\t[ OK ]\n");
+ succeed_cnt++;
+
+ if (file_frags_start != 1)
+ frag_files_after_defrag++;
+
+ extents_after_defrag += file_frags_start;
+ goto out;
+ }
+
/* Defrag the file */
ret = call_defrag(fd, donor_fd, file, buf, donor_list);
@@ -1192,6 +1245,7 @@ int main(int argc, char *argv[])
goto out;
current_uid = getuid();
+ threshold = DEFAULT_THRESHOLD;
/* Main process */
for (i = optind; i < argc; i++) {
--
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