Attached is the e2freefrag tool. It grabs the block bitmaps, creates
buddy bitmaps from them and displays the total/free chunks (default
1MB chunk size), and a histogram of free space.
It could probably be enhanced to print the chunk sizes based on the
RAID chunk size stored in the superblock, but I just thought of that
this minute...
Cheers, Andreas
--
Andreas Dilger
Sr. Staff Engineer, Lustre Group
Sun Microsystems of Canada, Inc.
Index: e2fsprogs-1.41.4/misc/e2freefrag.8.in
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ e2fsprogs-1.41.4/misc/e2freefrag.8.in 2009-04-21 13:24:09.000000000 -0600
@@ -0,0 +1,99 @@
+.\" -*- nroff -*-
+.TH E2FREEFRAG 8
+.SH NAME
+e2freefrag \- report free space fragmentation information
+.SH SYNOPSIS
+.B e2freefrag
+[
+.B \-c chunk_kb
+]
+[
+.B \-h
+]
+.B filesys
+
+.SH DESCRIPTION
+.B e2freefrag
+is used to report free space fragmentation on ext2/3/4 file systems.
+.I filesys
+is the filesystem device name (e.g.
+.IR /dev/hdc1 ", " /dev/md0 ).
+The
+.B e2freefrag
+program will scan the block bitmap information to check how many free blocks
+are present as contiguous and aligned free space. The percentage of contiguous
+free blocks of size and of alignment
+.IR chunk_kb
+is reported. It also displays the minimum/maximum/average free chunk size in
+the filesystem, along with a histogram of all free chunks. This information
+can be used to gauge the level of free space fragmentation in the filesystem.
+.SH OPTIONS
+.TP
+.BI \-c " chunk_kb"
+Desired size of chunk. It is specified in units of kilobytes (KB). If no
+.I chunk_kb
+is specified on the command line, then the default value is 1024KB.
+.TP
+.BI \-h
+Print the usage of the program.
+.SH EXAMPLE
+# e2freefrag /dev/vgroot/lvhome
+.br
+Device: /dev/vgroot/lvhome
+.br
+Blocksize: 4096 bytes
+.br
+Total blocks: 5120710
+.br
+Free blocks: 831744 (16.2%)
+.br
+Chunk size: 1048576 bytes (256 blocks)
+.br
+Total chunks: 20003
+.br
+Free chunks: 2174 (10.9%)
+.br
+
+Min free chunk: 4 KB
+.br
+Max free chunk: 24576 KB
+.br
+Avg. free chunk: 340 KB
+.br
+
+HISTOGRAM OF FREE CHUNK SIZES:
+.br
+ Range Free chunks
+.br
+ 4K... 8K- : 2824
+.br
+ 8K... 16K- : 1760
+.br
+ 16K... 32K- : 1857
+.br
+ 32K... 64K- : 1003
+.br
+ 64K... 128K- : 616
+.br
+ 128K... 256K- : 479
+.br
+ 256K... 512K- : 302
+.br
+ 512K... 1024K- : 238
+.br
+ 1M... 2M- : 213
+.br
+ 2M... 4M- : 173
+.br
+ 4M... 8M- : 287
+.br
+ 8M... 16M- : 4
+.br
+ 16M... 32M- : 1
+.SH AUTHOR
+This version of e2freefrag was written by Rupesh Thakare, and modified by
+Andreas Dilger <adilger@xxxxxxx>, and Kalpak Shah.
+.SH SEE ALSO
+.IR debugfs (8),
+.IR dumpe2fs (8),
+.IR e2fsck (8)
Index: e2fsprogs-1.41.4/misc/e2freefrag.c
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ e2fsprogs-1.41.4/misc/e2freefrag.c 2009-04-21 13:18:30.000000000 -0600
@@ -0,0 +1,275 @@
+/*
+ * e2freefrag - report filesystem free-space fragmentation
+ *
+ * Copyright (C) 2009 Sun Microsystems, Inc.
+ *
+ * Author: Rupesh Thakare <rupesh@xxxxxxx>
+ * Andreas Dilger <adilger@xxxxxxx>
+ *
+ * %Begin-Header%
+ * This file may be redistributed under the terms of the GNU Public
+ * License version 2.
+ * %End-Header%
+ */
+#include <stdio.h>
+#ifdef HAVE_UNISTD_H
+#include <unistd.h>
+#endif
+#ifdef HAVE_STDLIB_H
+#include <stdlib.h>
+#endif
+#ifdef HAVE_GETOPT_H
+#include <getopt.h>
+#else
+extern char *optarg;
+extern int optind;
+#endif
+
+#include "ext2fs/ext2_fs.h"
+#include "ext2fs/ext2fs.h"
+#include "e2freefrag.h"
+
+void usage(const char *prog)
+{
+ fprintf(stderr, "usage: %s [-c chunksize in kb] [-h] "
+ "device_name\n", prog);
+ exit(1);
+}
+
+static int ul_log2(unsigned long arg)
+{
+ int l = 0;
+
+ arg >>= 1;
+ while (arg) {
+ l++;
+ arg >>= 1;
+ }
+ return l;
+}
+
+void init_chunk_info(ext2_filsys fs, struct chunk_info *info)
+{
+ int i;
+
+ info->chunkbits = ul_log2(info->chunkbytes);
+ info->blocksize_bits = ul_log2((unsigned long)fs->blocksize);
+ info->blks_in_chunk = info->chunkbytes >> info->blocksize_bits;
+
+ info->min = ~0UL;
+ info->max = info->avg = 0;
+ info->real_free_chunks = 0;
+
+ for (i = 0; i < MAX_HIST; i++)
+ info->histogram.fc_buckets[i] = 0;
+}
+
+void scan_block_bitmap(ext2_filsys fs, struct chunk_info *info)
+{
+ unsigned long long blocks_count = fs->super->s_blocks_count;
+ unsigned long long chunks = (blocks_count + info->blks_in_chunk) >>
+ (info->chunkbits - info->blocksize_bits);
+ unsigned long long chunk_num;
+ unsigned long last_chunk_size = 0;
+ unsigned long long chunk_start_blk = 0;
+
+ for (chunk_num = 0; chunk_num < chunks; chunk_num++) {
+ unsigned long long blk, num_blks;
+ int chunk_free;
+
+ /* Last chunk may be smaller */
+ if (chunk_start_blk + info->blks_in_chunk > blocks_count)
+ num_blks = blocks_count - chunk_start_blk;
+ else
+ num_blks = info->blks_in_chunk;
+
+ chunk_free = 0;
+
+ /* Initialize starting block for first chunk correctly else
+ * there is a segfault when blocksize = 1024 in which case
+ * block_map->start = 1 */
+ for (blk = (chunk_num == 0 ? fs->super->s_first_data_block : 0);
+ blk < num_blks; blk++, chunk_start_blk++) {
+ int used = ext2fs_fast_test_block_bitmap(fs->block_map,
+ chunk_start_blk);
+ if (!used) {
+ last_chunk_size++;
+ chunk_free++;
+ }
+
+ if (used && last_chunk_size != 0) {
+ unsigned long index;
+
+ index = ul_log2(last_chunk_size) + 1;
+ info->histogram.fc_buckets[index]++;
+
+ if (last_chunk_size > info->max)
+ info->max = last_chunk_size;
+ if (last_chunk_size < info->min)
+ info->min = last_chunk_size;
+ info->avg += last_chunk_size;
+
+ info->real_free_chunks++;
+ last_chunk_size = 0;
+ }
+ }
+
+ if (chunk_free == info->blks_in_chunk)
+ info->free_chunks++;
+ }
+}
+
+errcode_t get_chunk_info(ext2_filsys fs, struct chunk_info *info)
+{
+ unsigned long total_chunks;
+ char *unitp = "KMGTPEZY";
+ int units = 10;
+ unsigned long start = 0, end, cum;
+ int i, retval = 0;
+
+ scan_block_bitmap(fs, info);
+
+ printf("Total blocks: %lu\nFree blocks: %lu (%0.1f%%)\n",
+ fs->super->s_blocks_count, fs->super->s_free_blocks_count,
+ (double)fs->super->s_free_blocks_count * 100 /
+ fs->super->s_blocks_count);
+
+ printf("\nChunksize: %u bytes (%u blocks)\n",
+ info->chunkbytes, info->blks_in_chunk);
+ total_chunks = (fs->super->s_blocks_count + info->blks_in_chunk) >>
+ (info->chunkbits - info->blocksize_bits);
+ printf("Total chunks: %lu\nFree chunks: %lu (%0.1f%%)\n",
+ total_chunks, info->free_chunks,
+ (double)info->free_chunks * 100 / total_chunks);
+
+ /* Display chunk information in KB */
+ if (info->real_free_chunks) {
+ info->min = (info->min * fs->blocksize) >> 10;
+ info->max = (info->max * fs->blocksize) >> 10;
+ info->avg = (info->avg / info->real_free_chunks *
+ fs->blocksize) >> 10;
+ } else {
+ info->min = 0;
+ }
+
+ printf("\nMin free chunk: %lu KB \nMax free chunk: %lu KB\n"
+ "Avg free chunk: %lu KB\n", info->min, info->max, info->avg);
+
+ printf("\nHISTOGRAM OF FREE CHUNK SIZES:\n");
+ printf("%s\t%10s\n", "Chunk Size Range :", "Free chunks");
+ for (i = 0; i < MAX_HIST; i++) {
+ end = 1 << (i + info->blocksize_bits - units);
+ if (info->histogram.fc_buckets[i] != 0)
+ printf("%5lu%c...%5lu%c- : %10lu\n", start, *unitp,
+ end, *unitp, info->histogram.fc_buckets[i]);
+ start = end;
+ if (start == 1<<10) {
+ start = 1;
+ units += 10;
+ unitp++;
+ }
+ }
+
+ return retval;
+}
+
+void close_device(char *device_name, ext2_filsys fs)
+{
+ int retval = ext2fs_close(fs);
+
+ if (retval)
+ com_err(device_name, retval, "while closing the filesystem.\n");
+}
+
+void collect_info(ext2_filsys fs, struct chunk_info *chunk_info)
+{
+ unsigned int retval = 0, i, free_blks;
+
+ printf("Device: %s\n", fs->device_name);
+ printf("Blocksize: %u bytes\n", fs->blocksize);
+
+ retval = ext2fs_read_block_bitmap(fs);
+ if (retval) {
+ com_err(fs->device_name, retval, "while reading block bitmap");
+ close_device(fs->device_name, fs);
+ exit(1);
+ }
+
+ init_chunk_info(fs, chunk_info);
+
+ retval = get_chunk_info(fs, chunk_info);
+ if (retval) {
+ com_err(fs->device_name, retval, "while collecting chunk info");
+ close_device(fs->device_name, fs);
+ exit(1);
+ }
+}
+
+void open_device(char *device_name, ext2_filsys *fs)
+{
+ int retval;
+ int flag = EXT2_FLAG_FORCE;
+
+ retval = ext2fs_open(device_name, flag, 0, 0, unix_io_manager, fs);
+ if (retval) {
+ com_err(device_name, retval, "while opening filesystem");
+ exit(1);
+ }
+}
+
+int main(int argc, char *argv[])
+{
+ struct chunk_info chunk_info = { .chunkbytes = DEFAULT_CHUNKSIZE };
+ errcode_t retval = 0;
+ ext2_filsys fs = NULL;
+ char *device_name;
+ char *progname;
+ char c, *end;
+
+ progname = argv[0];
+
+ while ((c = getopt(argc, argv, "c:h")) != EOF) {
+ switch (c) {
+ case 'c':
+ chunk_info.chunkbytes = strtoull(optarg, &end, 0);
+ if (*end != '\0') {
+ fprintf(stderr, "%s: bad chunk size '%s'\n",
+ progname, optarg);
+ usage(progname);
+ }
+ if (chunk_info.chunkbytes &
+ (chunk_info.chunkbytes - 1)) {
+ fprintf(stderr, "%s: chunk size must be a "
+ "power of 2.");
+ usage(progname);
+ }
+ chunk_info.chunkbytes *= 1024;
+ break;
+ default:
+ fprintf(stderr, "%s: bad option '%c'\n",
+ progname, c);
+ case 'h':
+ usage(progname);
+ break;
+ }
+ }
+
+ if (optind == argc) {
+ fprintf(stderr, "%s: missing device name.\n", progname);
+ usage(progname);
+ }
+
+ device_name = argv[optind];
+
+ open_device(device_name, &fs);
+
+ if (chunk_info.chunkbytes < fs->blocksize) {
+ fprintf(stderr, "%s: chunksize must be greater than or equal "
+ "to filesystem blocksize.\n", progname);
+ exit(1);
+ }
+ collect_info(fs, &chunk_info);
+ close_device(device_name, fs);
+
+ return retval;
+}
Index: e2fsprogs-1.41.4/misc/e2freefrag.h
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ e2fsprogs-1.41.4/misc/e2freefrag.h 2009-04-21 13:19:48.000000000 -0600
@@ -0,0 +1,19 @@
+#include <sys/types.h>
+
+#define DEFAULT_CHUNKSIZE (1024*1024)
+
+#define MAX_HIST 32
+struct free_chunk_histogram {
+ unsigned long fc_buckets[MAX_HIST];
+};
+
+struct chunk_info {
+ unsigned long chunkbytes; /* chunk size in bytes */
+ int chunkbits; /* chunk size in bits */
+ unsigned long free_chunks; /* total free chunks of given size */
+ unsigned long real_free_chunks; /* free chunks of any size */
+ int blocksize_bits; /* fs blocksize in bits */
+ int blks_in_chunk; /* number of blocks in a chunk */
+ unsigned long min, max, avg; /* chunk size stats */
+ struct free_chunk_histogram histogram; /* histogram of all chunk sizes*/
+};
Index: e2fsprogs-1.41.4/e2fsprogs.spec.in
===================================================================
--- e2fsprogs-1.41.4.orig/e2fsprogs.spec.in 2009-04-14 05:56:43.000000000 -0600
+++ e2fsprogs-1.41.4/e2fsprogs.spec.in 2009-04-21 13:25:19.000000000 -0600
@@ -143,6 +143,7 @@
%{_root_sbindir}/tune2fs
%{_sbindir}/filefrag
%{_sbindir}/mklost+found
+%{_sbindir}/e2freefrag
%{_root_libdir}/libblkid.so.*
%{_root_libdir}/libcom_err.so.*
@@ -187,6 +188,7 @@
%{_mandir}/man8/resize2fs.8*
%{_mandir}/man8/tune2fs.8*
%{_mandir}/man8/filefrag.8*
+%{_mandir}/man8/e2freefrag.8*
%files devel
%defattr(-,root,root)
Index: e2fsprogs-1.41.4/misc/Makefile.in
===================================================================
--- e2fsprogs-1.41.4.orig/misc/Makefile.in 2009-04-14 05:56:43.000000000 -0600
+++ e2fsprogs-1.41.4/misc/Makefile.in 2009-04-14 06:09:57.000000000 -0600
@@ -19,10 +19,10 @@
SPROGS= mke2fs badblocks tune2fs dumpe2fs $(BLKID_PROG) logsave \
$(E2IMAGE_PROG) @FSCK_PROG@ e2undo
-USPROGS= mklost+found filefrag $(UUIDD_PROG)
+USPROGS= mklost+found filefrag e2freefrag $(UUIDD_PROG)
SMANPAGES= tune2fs.8 mklost+found.8 mke2fs.8 dumpe2fs.8 badblocks.8 \
e2label.8 $(FINDFS_MAN) $(BLKID_MAN) $(E2IMAGE_MAN) \
- logsave.8 filefrag.8 e2undo.8 $(UUIDD_MAN) @FSCK_MAN@
+ logsave.8 filefrag.8 e2freefrag.8 e2undo.8 $(UUIDD_MAN) @FSCK_MAN@
FMANPAGES= mke2fs.conf.5
UPROGS= chattr lsattr uuidgen
@@ -44,6 +44,7 @@
BLKID_OBJS= blkid.o
FILEFRAG_OBJS= filefrag.o
E2UNDO_OBJS= e2undo.o
+E2FREEFRAG_OBJS= e2freefrag.o
PROFILED_TUNE2FS_OBJS= profiled/tune2fs.o profiled/util.o
PROFILED_MKLPF_OBJS= profiled/mklost+found.o
@@ -71,7 +72,7 @@
$(srcdir)/uuidgen.c $(srcdir)/blkid.c $(srcdir)/logsave.c \
$(srcdir)/filefrag.c $(srcdir)/base_device.c \
$(srcdir)/ismounted.c $(srcdir)/../e2fsck/profile.c \
- $(srcdir)/e2undo.c
+ $(srcdir)/e2undo.c $(srcdir)/e2freefrag.c
LIBS= $(LIBEXT2FS) $(LIBCOM_ERR)
DEPLIBS= $(LIBEXT2FS) $(LIBCOM_ERR)
@@ -276,6 +277,10 @@
@echo " LD $@"
@$(CC) $(ALL_LDFLAGS) -g -pg -o logsave.profiled profiled/logsave.o
+e2freefrag: $(E2FREEFRAG_OBJS)
+ @echo "LD $@"
+ @$(CC) $(ALL_LDFLAGS) -o e2freefrag $(E2FREEFRAG_OBJS) $(LIBS)
+
filefrag: $(FILEFRAG_OBJS)
@echo " LD $@"
@$(CC) $(ALL_LDFLAGS) -o filefrag $(FILEFRAG_OBJS)
@@ -361,6 +366,10 @@
@echo " SUBST $@"
@$(SUBSTITUTE_UPTIME) $(srcdir)/blkid.1.in blkid.1
+e2freefrag.8: $(DEP_SUBSTITUTE) $(srcdir)/e2freefrag.8.in
+ @echo " SUBST $@"
+ @$(SUBSTITUTE_UPTIME) $(srcdir)/e2freefrag.8.in e2freefrag.8
+
filefrag.8: $(DEP_SUBSTITUTE) $(srcdir)/filefrag.8.in
@echo " SUBST $@"
@$(SUBSTITUTE_UPTIME) $(srcdir)/filefrag.8.in filefrag.8
@@ -522,7 +531,7 @@
clean:
$(RM) -f $(SPROGS) $(USPROGS) $(UPROGS) $(UMANPAGES) $(SMANPAGES) \
$(FMANPAGES) \
- base_device base_device.out mke2fs.static filefrag \
+ base_device base_device.out mke2fs.static filefrag e2freefrag \
e2initrd_helper partinfo prof_err.[ch] default_profile.c \
uuidd e2image tune2fs.static tst_ismounted fsck.profiled \
blkid.profiled tune2fs.profiled e2image.profiled \
@@ -603,6 +612,9 @@
blkid.o: $(srcdir)/blkid.c $(top_srcdir)/lib/blkid/blkid.h \
$(top_builddir)/lib/blkid/blkid_types.h
logsave.o: $(srcdir)/logsave.c
+e2freefrag.o: $(srcdir)/e2freefrag.c e2freefrag.h \
+ $(top_srcdir)/lib/ext2fs/ext2_fs.h $(top_srcdir)/lib/ext2fs/ext2fs.h \
+ $(top_srcdir)/lib/ext2fs/bitops.h
filefrag.o: $(srcdir)/filefrag.c
base_device.o: $(srcdir)/base_device.c $(srcdir)/fsck.h
ismounted.o: $(srcdir)/ismounted.c $(top_srcdir)/lib/et/com_err.h
