available space reduce sharply in the jffs2 file system
汤磊金
leijint at mobilesoft.com.cn
Fri Nov 11 01:26:40 EST 2005
linux-mtd，您好！
we take some experiments in the jffs2 file system of linux kernel 2.6.12.we caught a big problem.
we write 4 bytes and we random llseek in the jffs2,the available space continue to reduce sharply.
fd = fopen(argv[1], "r+");
char buf[1024]={'a','b','c'};
for (;;) {
offset = rand();
fseek(fd, offset % (1024*1024), SEEK_SET);
fwrite(buf, 1024, 1, fd);
}
fclose(fd);
we caught the slabinfo in the proc every other 10 second.
<active_objs> <num_objs> <objsize>
jffs2_inode_cache 1998 2030 24 145 1 : tunables 120 60 0 : slabdata 14 140
jffs2_node_frag 1936 2032 28 127 1 : tunables 120 60 0 : slabdata 16 160
jffs2_raw_node_ref 11529 11571 16 203 1 : tunables 120 60 0 : slabdata 57 50
jffs2_tmp_dnode 0 0 36 101 1 : tunables 120 60 0 : slabdata 0 00
jffs2_raw_inode 0 0 68 56 1 : tunables 120 60 0 : slabdata 0 00
jffs2_raw_dirent 0 0 40 92 1 : tunables 120 60 0 : slabdata 0 00
jffs2_full_dnode 2116 2233 16 203 1 : tunables 120 60 0 : slabdata 11 110
jffs2_inode_cache 2006 2030 24 145 1 : tunables 120 60 0 : slabdata 14 140
jffs2_node_frag 3870 3937 28 127 1 : tunables 120 60 0 : slabdata 31 310
jffs2_raw_node_ref 12443 12586 16 203 1 : tunables 120 60 0 : slabdata 62 60
jffs2_tmp_dnode 1 101 36 101 1 : tunables 120 60 0 : slabdata 1 10
jffs2_raw_inode 2 56 68 56 1 : tunables 120 60 0 : slabdata 1 10
jffs2_raw_dirent 8 92 40 92 1 : tunables 120 60 0 : slabdata 1 10
jffs2_full_dnode 4037 4060 16 203 1 : tunables 120 60 0 : slabdata 20 200
jffs2_inode_cache 1999 2030 24 145 1 : tunables 120 60 0 : slabdata 14 140
jffs2_node_frag 4811 4826 28 127 1 : tunables 120 60 0 : slabdata 38 380
jffs2_raw_node_ref 13400 13601 16 203 1 : tunables 120 60 0 : slabdata 67 60
jffs2_tmp_dnode 0 0 36 101 1 : tunables 120 60 0 : slabdata 0 00
jffs2_raw_inode 0 56 68 56 1 : tunables 120 60 0 : slabdata 0 10
jffs2_raw_dirent 0 0 40 92 1 : tunables 120 60 0 : slabdata 0 00
jffs2_full_dnode 4943 5075 16 203 1 : tunables 120 60 0 : slabdata 25 250
eadline_drq 8 78 48 78 1 : tunables 120 60 0 : slabdata 1 10
jffs2_inode_cache 1999 2030 24 145 1 : tunables 120 60 0 : slabdata 14 140
jffs2_node_frag 5698 5715 28 127 1 : tunables 120 60 0 : slabdata 45 450
jffs2_raw_node_ref 14337 14413 16 203 1 : tunables 120 60 0 : slabdata 71 70
jffs2_tmp_dnode 0 0 36 101 1 : tunables 120 60 0 : slabdata 0 00
jffs2_raw_inode 2 56 68 56 1 : tunables 120 60 0 : slabdata 1 10
jffs2_raw_dirent 0 0 40 92 1 : tunables 120 60 0 : slabdata 0 00
jffs2_full_dnode 5795 5887 16 203 1 : tunables 120 60 0 : slabdata 29 290
jffs2_inode_cache 1999 2030 24 145 1 : tunables 120 60 0 : slabdata 14 140
jffs2_node_frag 6587 6604 28 127 1 : tunables 120 60 0 : slabdata 52 520
jffs2_raw_node_ref 15269 15428 16 203 1 : tunables 120 60 0 : slabdata 76 70
jffs2_tmp_dnode 0 0 36 101 1 : tunables 120 60 0 : slabdata 0 00
jffs2_raw_inode 4 56 68 56 1 : tunables 120 60 0 : slabdata 1 10
jffs2_raw_dirent 0 0 40 92 1 : tunables 120 60 0 : slabdata 0 00
jffs2_full_dnode 6649 6699 16 203 1 : tunables 120 60 0 : slabdata 33 330
the same testing codes is running in the system of kernel version 2.4.18,but the slabinfo is as follow:
jffs2_inode_cache 502 507 20 3 3 1
jffs2_node_frag 336 606 16 3 3 1
jffs2_raw_node_ref 4525 4646 16 23 23 1
jffs2_tmp_dnode 0 253 12 0 1 1
jffs2_raw_inode 1 56 68 1 1 1
jffs2_raw_dirent 0 92 40 0 1 1
jffs2_full_dnode 356 808 16 4 4 1
jffs2_inode_cache 502 507 20 3 3 1
jffs2_node_frag 355 606 16 3 3 1
jffs2_raw_node_ref 6175 6262 16 31 31 1
jffs2_tmp_dnode 0 253 12 0 1 1
jffs2_raw_inode 1 56 68 1 1 1
jffs2_raw_dirent 0 92 40 0 1 1
jffs2_full_dnode 375 808 16 4 4 1
jffs2_inode_cache 502 507 20 3 3 1
jffs2_node_frag 360 606 16 3 3 1
jffs2_raw_node_ref 6660 6666 16 33 33 1
jffs2_tmp_dnode 0 253 12 0 1 1
jffs2_raw_inode 0 56 68 0 1 1
jffs2_raw_dirent 0 92 40 0 1 1
jffs2_full_dnode 379 808 16 4 4 1
jffs2_inode_cache 502 507 20 3 3 1
jffs2_node_frag 465 606 16 3 3 1
jffs2_raw_node_ref 7744 7878 16 39 39 1
jffs2_tmp_dnode 0 253 12 0 1 1
jffs2_raw_inode 0 56 68 0 1 1
jffs2_raw_dirent 0 92 40 0 1 1
jffs2_full_dnode 632 808 16 4 4 1
jffs2_inode_cache 436 507 20 3 3 1
jffs2_node_frag 566 606 16 3 3 1
jffs2_raw_node_ref 5982 7878 16 31 39 1
jffs2_tmp_dnode 0 253 12 0 1 1
jffs2_raw_inode 0 56 68 0 1 1
jffs2_raw_dirent 0 92 40 0 1 1
jffs2_full_dnode 750 808 16 4 4 1
jffs2_inode_cache 436 507 20 3 3 1
jffs2_node_frag 581 606 16 3 3 1
jffs2_raw_node_ref 5544 7878 16 28 39 1
jffs2_tmp_dnode 0 253 12 0 1 1
jffs2_raw_inode 0 56 68 0 1 1
jffs2_raw_dirent 0 92 40 0 1 1
jffs2_full_dnode 765 808 16 4 4 1
jffs2_inode_cache 436 507 20 3 3 1
jffs2_node_frag 615 808 16 4 4 1
jffs2_raw_node_ref 4863 7878 16 31 39 1
jffs2_tmp_dnode 0 253 12 0 1 1
jffs2_raw_inode 0 56 68 0 1 1
jffs2_raw_dirent 0 92 40 0 1 1
jffs2_full_dnode 799 808 16 4 4 1
we also take anthor testing in the kernel 2.6.12. the codes is as follows:
fd = fopen(argv[1], "r+");
for (;;) {
fwrite(&offset,sizeof(int), 1, fd);
offset += 4;
if (offset >= 1024*1024) {
offset = 0;
fseek(fd, 0, SEEK_SET);
}
}
fclose(fd);
there is no problem in the jffs2 file system and the system's space is decrease about 100K when we write 1M bytes.
we felt the reason is mabye the principles of Garbage collection. when we run the test codes in the kernel 2.4.18 or write data orderly,the jffs2_raw_node_ref is keeping quantity.
Any help is much appreciated.
致
礼！
汤磊金
leijint at mobilesoft.com.cn
2005-11-11
More information about the linux-mtd
mailing list