Directory layout preference improvements from Grigoriy Orlov <gluk@ptci.ru>.
His description of the problem and solution follow. My own tests show speedups on typical filesystem intensive workloads of 5% to 12% which is very impressive considering the small amount of code change involved. ------ One day I noticed that some file operations run much faster on small file systems then on big ones. I've looked at the ffs algorithms, thought about them, and redesigned the dirpref algorithm. First I want to describe the results of my tests. These results are old and I have improved the algorithm after these tests were done. Nevertheless they show how big the perfomance speedup may be. I have done two file/directory intensive tests on a two OpenBSD systems with old and new dirpref algorithm. The first test is "tar -xzf ports.tar.gz", the second is "rm -rf ports". The ports.tar.gz file is the ports collection from the OpenBSD 2.8 release. It contains 6596 directories and 13868 files. The test systems are: 1. Celeron-450, 128Mb, two IDE drives, the system at wd0, file system for test is at wd1. Size of test file system is 8 Gb, number of cg=991, size of cg is 8m, block size = 8k, fragment size = 1k OpenBSD-current from Dec 2000 with BUFCACHEPERCENT=35 2. PIII-600, 128Mb, two IBM DTLA-307045 IDE drives at i815e, the system at wd0, file system for test is at wd1. Size of test file system is 40 Gb, number of cg=5324, size of cg is 8m, block size = 8k, fragment size = 1k OpenBSD-current from Dec 2000 with BUFCACHEPERCENT=50 You can get more info about the test systems and methods at: http://www.ptci.ru/gluk/dirpref/old/dirpref.html Test Results tar -xzf ports.tar.gz rm -rf ports mode old dirpref new dirpref speedup old dirprefnew dirpref speedup First system normal 667 472 1.41 477 331 1.44 async 285 144 1.98 130 14 9.29 sync 768 616 1.25 477 334 1.43 softdep 413 252 1.64 241 38 6.34 Second system normal 329 81 4.06 263.5 93.5 2.81 async 302 25.7 11.75 112 2.26 49.56 sync 281 57.0 4.93 263 90.5 2.9 softdep 341 40.6 8.4 284 4.76 59.66 "old dirpref" and "new dirpref" columns give a test time in seconds. speedup - speed increasement in times, ie. old dirpref / new dirpref. ------ Algorithm description The old dirpref algorithm is described in comments: /* * Find a cylinder to place a directory. * * The policy implemented by this algorithm is to select from * among those cylinder groups with above the average number of * free inodes, the one with the smallest number of directories. */ A new directory is allocated in a different cylinder groups than its parent directory resulting in a directory tree that is spreaded across all the cylinder groups. This spreading out results in a non-optimal access to the directories and files. When we have a small filesystem it is not a problem but when the filesystem is big then perfomance degradation becomes very apparent. What I mean by a big file system ? 1. A big filesystem is a filesystem which occupy 20-30 or more percent of total drive space, i.e. first and last cylinder are physically located relatively far from each other. 2. It has a relatively large number of cylinder groups, for example more cylinder groups than 50% of the buffers in the buffer cache. The first results in long access times, while the second results in many buffers being used by metadata operations. Such operations use cylinder group blocks and on-disk inode blocks. The cylinder group block (fs->fs_cblkno) contains struct cg, inode and block bit maps. It is 2k in size for the default filesystem parameters. If new and parent directories are located in different cylinder groups then the system performs more input/output operations and uses more buffers. On filesystems with many cylinder groups, lots of cache buffers are used for metadata operations. My solution for this problem is very simple. I allocate many directories in one cylinder group. I also do some things, so that the new allocation method does not cause excessive fragmentation and all directory inodes will not be located at a location far from its file's inodes and data. The algorithm is: /* * Find a cylinder group to place a directory. * * The policy implemented by this algorithm is to allocate a * directory inode in the same cylinder group as its parent * directory, but also to reserve space for its files inodes * and data. Restrict the number of directories which may be * allocated one after another in the same cylinder group * without intervening allocation of files. * * If we allocate a first level directory then force allocation * in another cylinder group. */ My early versions of dirpref give me a good results for a wide range of file operations and different filesystem capacities except one case: those applications that create their entire directory structure first and only later fill this structure with files. My solution for such and similar cases is to limit a number of directories which may be created one after another in the same cylinder group without intervening file creations. For this purpose, I allocate an array of counters at mount time. This array is linked to the superblock fs->fs_contigdirs[cg]. Each time a directory is created the counter increases and each time a file is created the counter decreases. A 60Gb filesystem with 8mb/cg requires 10kb of memory for the counters array. The maxcontigdirs is a maximum number of directories which may be created without an intervening file creation. I found in my tests that the best performance occurs when I restrict the number of directories in one cylinder group such that all its files may be located in the same cylinder group. There may be some deterioration in performance if all the file inodes are in the same cylinder group as its containing directory, but their data partially resides in a different cylinder group. The maxcontigdirs value is calculated to try to prevent this condition. Since there is no way to know how many files and directories will be allocated later I added two optimization parameters in superblock/tunefs. They are: int32_t fs_avgfilesize; /* expected average file size */ int32_t fs_avgfpdir; /* expected # of files per directory */ These parameters have reasonable defaults but may be tweeked for special uses of a filesystem. They are only necessary in rare cases like better tuning a filesystem being used to store a squid cache. I have been using this algorithm for about 3 months. I have done a lot of testing on filesystems with different capacities, average filesize, average number of files per directory, and so on. I think this algorithm has no negative impact on filesystem perfomance. It works better than the default one in all cases. The new dirpref will greatly improve untarring/removing/coping of big directories, decrease load on cvs servers and much more. The new dirpref doesn't speedup a compilation process, but also doesn't slow it down. Obtained from: Grigoriy Orlov <gluk@ptci.ru>
This commit is contained in:
mckusick
parent
0e306cda1d
commit
3931e94b1f
@ -119,6 +119,8 @@ extern int maxbpg; /* maximum blocks per file in a cyl group */
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extern int nrpos; /* # of distinguished rotational positions */
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extern int bbsize; /* boot block size */
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extern int sbsize; /* superblock size */
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extern int avgfilesize; /* expected average file size */
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extern int avgfilesperdir; /* expected number of files per directory */
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extern u_long memleft; /* virtual memory available */
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extern caddr_t membase; /* start address of memory based filesystem */
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extern char * filename;
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@ -273,6 +275,17 @@ mkfs(pp, fsys, fi, fo)
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printf("preposterous ntrak %d\n", sblock.fs_ntrak), exit(14);
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if (sblock.fs_nsect <= 0)
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printf("preposterous nsect %d\n", sblock.fs_nsect), exit(15);
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/*
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* collect and verify the filesystem density info
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*/
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sblock.fs_avgfilesize = avgfilesize;
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sblock.fs_avgfpdir = avgfilesperdir;
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if (sblock.fs_avgfilesize <= 0)
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printf("illegal expected average file size %d\n",
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sblock.fs_avgfilesize), exit(14);
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if (sblock.fs_avgfpdir <= 0)
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printf("illegal expected number of files per directory %d\n",
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sblock.fs_avgfpdir), exit(15);
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/*
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* collect and verify the block and fragment sizes
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*/
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@ -163,9 +163,7 @@ void fatal();
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* The number of sectors are used to determine the size of a cyl-group.
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* Kirk suggested one or two meg per "cylinder" so we say two.
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*/
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#define NTRACKS 1 /* number of heads */
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#define NSECTORS 4096 /* number of sectors */
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int mfs; /* run as the memory based filesystem */
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@ -199,6 +197,8 @@ int maxcontig = 0; /* max contiguous blocks to allocate */
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int rotdelay = ROTDELAY; /* rotational delay between blocks */
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int maxbpg; /* maximum blocks per file in a cyl group */
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int nrpos = NRPOS; /* # of distinguished rotational positions */
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int avgfilesize = AVFILESIZ;/* expected average file size */
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int avgfilesperdir = AFPDIR;/* expected number of files per directory */
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int bbsize = BBSIZE; /* boot block size */
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int sbsize = SBSIZE; /* superblock size */
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int mntflags = MNT_ASYNC; /* flags to be passed to mount */
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@ -256,8 +256,8 @@ main(argc, argv)
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}
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opstring = mfs ?
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"NF:T:Ua:b:c:d:e:f:i:m:o:s:" :
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"NOS:T:Ua:b:c:d:e:f:i:k:l:m:n:o:p:r:s:t:u:vx:";
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"NF:T:Ua:b:c:d:e:f:g:h:i:m:o:s:" :
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"NOS:T:Ua:b:c:d:e:f:g:h:i:k:l:m:n:o:p:r:s:t:u:vx:";
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while ((ch = getopt(argc, argv, opstring)) != -1)
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switch (ch) {
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case 'N':
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@ -308,6 +308,14 @@ main(argc, argv)
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if ((fsize = atoi(optarg)) <= 0)
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fatal("%s: bad fragment size", optarg);
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break;
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case 'g':
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if ((avgfilesize = atoi(optarg)) <= 0)
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fatal("%s: bad average file size", optarg);
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break;
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case 'h':
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if ((avgfilesperdir = atoi(optarg)) <= 0)
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fatal("%s: bad average files per dir", optarg);
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break;
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case 'i':
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if ((density = atoi(optarg)) <= 0)
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fatal("%s: bad bytes per inode", optarg);
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@ -768,6 +776,8 @@ usage()
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fprintf(stderr, "\t-d rotational delay between contiguous blocks\n");
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fprintf(stderr, "\t-e maximum blocks per file in a cylinder group\n");
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fprintf(stderr, "\t-f frag size\n");
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fprintf(stderr, "\t-g average file size\n");
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fprintf(stderr, "\t-h average files per directory\n");
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fprintf(stderr, "\t-i number of bytes per inode\n");
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fprintf(stderr, "\t-k sector 0 skew, per track\n");
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fprintf(stderr, "\t-l hardware sector interleave\n");
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@ -91,9 +91,10 @@ main(argc, argv)
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char *special, *name;
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struct stat st;
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int Aflag = 0, active = 0;
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int aflag = 0, dflag = 0, eflag = 0, mflag = 0;
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int nflag = 0, oflag = 0, pflag = 0;
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int avalue = 0, dvalue = 0, evalue = 0, mvalue = 0, ovalue = 0;
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int aflag = 0, dflag = 0, eflag = 0, fflag = 0, mflag = 0;
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int nflag = 0, oflag = 0, pflag = 0, sflag = 0;
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int avalue = 0, dvalue = 0, evalue = 0, fvalue = 0;
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int mvalue = 0, ovalue = 0, svalue = 0;
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char *nvalue = NULL;
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struct fstab *fs;
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char *chg[2], device[MAXPATHLEN];
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@ -104,7 +105,7 @@ main(argc, argv)
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if (argc < 3)
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usage();
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found_arg = 0; /* at least one arg is required */
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while ((ch = getopt(argc, argv, "Aa:d:e:m:n:o:p")) != -1)
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while ((ch = getopt(argc, argv, "Aa:d:e:f:m:n:o:ps:")) != -1)
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switch (ch) {
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case 'A':
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found_arg = 1;
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@ -132,6 +133,14 @@ main(argc, argv)
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errx(10, "%s must be >= 1 (was %s)", name, optarg);
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eflag = 1;
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break;
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case 'f':
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found_arg = 1;
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name = "average file size";
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fvalue = atoi(optarg);
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if (fvalue < 1)
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errx(10, "%s must be >= 1 (was %s)", name, optarg);
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fflag = 1;
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break;
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case 'm':
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found_arg = 1;
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name = "minimum percentage of free space";
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@ -168,6 +177,14 @@ main(argc, argv)
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found_arg = 1;
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pflag = 1;
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break;
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case 's':
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found_arg = 1;
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name = "expected number of files per directory";
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svalue = atoi(optarg);
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if (svalue < 1)
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errx(10, "%s must be >= 1 (was %s)", name, optarg);
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sflag = 1;
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break;
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default:
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usage();
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}
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@ -239,6 +256,17 @@ main(argc, argv)
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sblock.fs_maxbpg = evalue;
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}
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}
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if (fflag) {
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name = "average file size";
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if (sblock.fs_avgfilesize == fvalue) {
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warnx("%s remains unchanged as %d", name, fvalue);
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}
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else {
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warnx("%s changes from %d to %d",
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name, sblock.fs_avgfilesize, fvalue);
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sblock.fs_avgfilesize = fvalue;
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}
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}
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if (mflag) {
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name = "minimum percentage of free space";
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if (sblock.fs_minfree == mvalue) {
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@ -291,6 +319,17 @@ main(argc, argv)
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warnx(OPTWARN, "space", "<", MINFREE);
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}
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}
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if (sflag) {
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name = "expected number of files per directory";
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if (sblock.fs_avgfpdir == svalue) {
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warnx("%s remains unchanged as %d", name, svalue);
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}
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else {
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warnx("%s changes from %d to %d",
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name, sblock.fs_avgfpdir, svalue);
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sblock.fs_avgfpdir = svalue;
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}
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}
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putsb(&sblock, special, Aflag);
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if (active) {
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@ -307,9 +346,9 @@ void
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usage()
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{
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fprintf(stderr, "%s\n%s\n%s\n",
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"usage: tunefs [-A] [-a maxcontig] [-d rotdelay] [-e maxbpg] [-m minfree]",
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" [-p] [-n enable | disable] [-o space | time]",
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" special | filesystem");
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"usage: tunefs [-A] [-a maxcontig] [-d rotdelay] [-e maxbpg] [-f avgfilesize]",
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" [-m minfree] [-p] [-n enable | disable] [-o space | time]",
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" [-s filesperdir] special | filesystem");
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exit(2);
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}
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@ -366,6 +405,10 @@ printfs()
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sblock.fs_rotdelay);
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warnx("maximum blocks per file in a cylinder group: (-e) %d",
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sblock.fs_maxbpg);
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warnx("average file size: (-f) %d",
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sblock.fs_avgfilesize);
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warnx("average number of files in a directory: (-s) %d",
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sblock.fs_avgfpdir);
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warnx("minimum percentage of free space: (-m) %d%%",
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sblock.fs_minfree);
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warnx("optimization preference: (-o) %s",
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@ -71,7 +71,7 @@ static void ffs_clusteracct __P((struct fs *, struct cg *, ufs_daddr_t,
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int));
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static ufs_daddr_t ffs_clusteralloc __P((struct inode *, int, ufs_daddr_t,
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int));
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static ino_t ffs_dirpref __P((struct fs *));
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static ino_t ffs_dirpref __P((struct inode *));
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static ufs_daddr_t ffs_fragextend __P((struct inode *, int, long, int, int));
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static void ffs_fserr __P((struct fs *, u_int, char *));
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static u_long ffs_hashalloc
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@ -593,12 +593,23 @@ ffs_valloc(pvp, mode, cred, vpp)
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goto noinodes;
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if ((mode & IFMT) == IFDIR)
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ipref = ffs_dirpref(fs);
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ipref = ffs_dirpref(pip);
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else
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ipref = pip->i_number;
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if (ipref >= fs->fs_ncg * fs->fs_ipg)
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ipref = 0;
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cg = ino_to_cg(fs, ipref);
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/*
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* Track number of dirs created one after another
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* in a same cg without intervening by files.
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*/
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if ((mode & IFMT) == IFDIR) {
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if (fs->fs_contigdirs[cg] < 255)
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fs->fs_contigdirs[cg]++;
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} else {
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if (fs->fs_contigdirs[cg] > 0)
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fs->fs_contigdirs[cg]--;
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}
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ino = (ino_t)ffs_hashalloc(pip, cg, (long)ipref, mode,
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(allocfcn_t *)ffs_nodealloccg);
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if (ino == 0)
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@ -633,28 +644,112 @@ ffs_valloc(pvp, mode, cred, vpp)
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}
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/*
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* Find a cylinder to place a directory.
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* Find a cylinder group to place a directory.
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*
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* The policy implemented by this algorithm is to select from
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* among those cylinder groups with above the average number of
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* free inodes, the one with the smallest number of directories.
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* The policy implemented by this algorithm is to allocate a
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* directory inode in the same cylinder group as its parent
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* directory, but also to reserve space for its files inodes
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* and data. Restrict the number of directories which may be
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* allocated one after another in the same cylinder group
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* without intervening allocation of files.
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*
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* If we allocate a first level directory then force allocation
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* in another cylinder group.
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*/
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static ino_t
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ffs_dirpref(fs)
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register struct fs *fs;
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ffs_dirpref(pip)
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struct inode *pip;
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{
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int cg, minndir, mincg, avgifree;
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register struct fs *fs;
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int cg, prefcg, dirsize, cgsize;
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int avgifree, avgbfree, avgndir, curdirsize;
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int minifree, minbfree, maxndir;
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int mincg, minndir;
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int maxcontigdirs;
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fs = pip->i_fs;
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avgifree = fs->fs_cstotal.cs_nifree / fs->fs_ncg;
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minndir = fs->fs_ipg;
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mincg = 0;
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for (cg = 0; cg < fs->fs_ncg; cg++)
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if (fs->fs_cs(fs, cg).cs_ndir < minndir &&
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fs->fs_cs(fs, cg).cs_nifree >= avgifree) {
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mincg = cg;
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minndir = fs->fs_cs(fs, cg).cs_ndir;
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avgbfree = fs->fs_cstotal.cs_nbfree / fs->fs_ncg;
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avgndir = fs->fs_cstotal.cs_ndir / fs->fs_ncg;
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/*
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* Force allocation in another cg if creating a first level dir.
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*/
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if (ITOV(pip)->v_flag & VROOT) {
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prefcg = arc4random() % fs->fs_ncg;
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mincg = prefcg;
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minndir = fs->fs_ipg;
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for (cg = prefcg; cg < fs->fs_ncg; cg++)
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if (fs->fs_cs(fs, cg).cs_ndir < minndir &&
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fs->fs_cs(fs, cg).cs_nifree >= avgifree &&
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fs->fs_cs(fs, cg).cs_nbfree >= avgbfree) {
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mincg = cg;
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minndir = fs->fs_cs(fs, cg).cs_ndir;
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}
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for (cg = 0; cg < prefcg; cg++)
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if (fs->fs_cs(fs, cg).cs_ndir < minndir &&
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fs->fs_cs(fs, cg).cs_nifree >= avgifree &&
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fs->fs_cs(fs, cg).cs_nbfree >= avgbfree) {
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mincg = cg;
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minndir = fs->fs_cs(fs, cg).cs_ndir;
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}
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return ((ino_t)(fs->fs_ipg * mincg));
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}
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/*
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* Count various limits which used for
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* optimal allocation of a directory inode.
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*/
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maxndir = min(avgndir + fs->fs_ipg / 16, fs->fs_ipg);
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minifree = avgifree - fs->fs_ipg / 4;
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if (minifree < 0)
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minifree = 0;
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minbfree = avgbfree - fs->fs_fpg / fs->fs_frag / 4;
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if (minbfree < 0)
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minbfree = 0;
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cgsize = fs->fs_fsize * fs->fs_fpg;
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dirsize = fs->fs_avgfilesize * fs->fs_avgfpdir;
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curdirsize = avgndir ? (cgsize - avgbfree * fs->fs_bsize) / avgndir : 0;
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if (dirsize < curdirsize)
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dirsize = curdirsize;
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maxcontigdirs = min(cgsize / dirsize, 255);
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if (fs->fs_avgfpdir > 0)
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maxcontigdirs = min(maxcontigdirs,
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fs->fs_ipg / fs->fs_avgfpdir);
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if (maxcontigdirs == 0)
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maxcontigdirs = 1;
|
||||
|
||||
/*
|
||||
* Limit number of dirs in one cg and reserve space for
|
||||
* regular files, but only if we have no deficit in
|
||||
* inodes or space.
|
||||
*/
|
||||
prefcg = ino_to_cg(fs, pip->i_number);
|
||||
for (cg = prefcg; cg < fs->fs_ncg; cg++)
|
||||
if (fs->fs_cs(fs, cg).cs_ndir < maxndir &&
|
||||
fs->fs_cs(fs, cg).cs_nifree >= minifree &&
|
||||
fs->fs_cs(fs, cg).cs_nbfree >= minbfree) {
|
||||
if (fs->fs_contigdirs[cg] < maxcontigdirs)
|
||||
return ((ino_t)(fs->fs_ipg * cg));
|
||||
}
|
||||
return ((ino_t)(fs->fs_ipg * mincg));
|
||||
for (cg = 0; cg < prefcg; cg++)
|
||||
if (fs->fs_cs(fs, cg).cs_ndir < maxndir &&
|
||||
fs->fs_cs(fs, cg).cs_nifree >= minifree &&
|
||||
fs->fs_cs(fs, cg).cs_nbfree >= minbfree) {
|
||||
if (fs->fs_contigdirs[cg] < maxcontigdirs)
|
||||
return ((ino_t)(fs->fs_ipg * cg));
|
||||
}
|
||||
/*
|
||||
* This is a backstop when we have deficit in space.
|
||||
*/
|
||||
for (cg = prefcg; cg < fs->fs_ncg; cg++)
|
||||
if (fs->fs_cs(fs, cg).cs_nifree >= avgifree)
|
||||
return ((ino_t)(fs->fs_ipg * cg));
|
||||
for (cg = 0; cg < prefcg; cg++)
|
||||
if (fs->fs_cs(fs, cg).cs_nifree >= avgifree)
|
||||
break;
|
||||
return ((ino_t)(fs->fs_ipg * cg));
|
||||
}
|
||||
|
||||
/*
|
||||
|
||||
@ -624,6 +624,7 @@ ffs_mountfs(devvp, mp, p, malloctype)
|
||||
blks = howmany(size, fs->fs_fsize);
|
||||
if (fs->fs_contigsumsize > 0)
|
||||
size += fs->fs_ncg * sizeof(int32_t);
|
||||
size += fs->fs_ncg * sizeof(u_int8_t);
|
||||
space = malloc((u_long)size, M_UFSMNT, M_WAITOK);
|
||||
fs->fs_csp = space;
|
||||
for (i = 0; i < blks; i += fs->fs_frag) {
|
||||
@ -645,6 +646,15 @@ ffs_mountfs(devvp, mp, p, malloctype)
|
||||
for (i = 0; i < fs->fs_ncg; i++)
|
||||
*lp++ = fs->fs_contigsumsize;
|
||||
}
|
||||
size = fs->fs_ncg * sizeof(u_int8_t);
|
||||
fs->fs_contigdirs = (u_int8_t *)space;
|
||||
space = (u_int8_t *)space + size;
|
||||
bzero(fs->fs_contigdirs, size);
|
||||
/* Compatibility for old filesystems XXX */
|
||||
if (fs->fs_avgfilesize <= 0) /* XXX */
|
||||
fs->fs_avgfilesize = AVFILESIZ; /* XXX */
|
||||
if (fs->fs_avgfpdir <= 0) /* XXX */
|
||||
fs->fs_avgfpdir = AFPDIR; /* XXX */
|
||||
mp->mnt_data = (qaddr_t)ump;
|
||||
mp->mnt_stat.f_fsid.val[0] = fs->fs_id[0];
|
||||
mp->mnt_stat.f_fsid.val[1] = fs->fs_id[1];
|
||||
|
||||
@ -108,15 +108,17 @@
|
||||
/*
|
||||
* There is a 128-byte region in the superblock reserved for in-core
|
||||
* pointers to summary information. Originally this included an array
|
||||
* of pointers to blocks of struct csum; now there are just two
|
||||
* of pointers to blocks of struct csum; now there are just three
|
||||
* pointers and the remaining space is padded with fs_ocsp[].
|
||||
*
|
||||
* NOCSPTRS determines the size of this padding. One pointer (fs_csp)
|
||||
* is taken away to point to a contiguous array of struct csum for
|
||||
* all cylinder groups; a second (fs_maxcluster) points to an array
|
||||
* of cluster sizes that is computed as cylinder groups are inspected.
|
||||
* of cluster sizes that is computed as cylinder groups are inspected,
|
||||
* and the third points to an array that tracks the creation of new
|
||||
* directories.
|
||||
*/
|
||||
#define NOCSPTRS ((128 / sizeof(void *)) - 2)
|
||||
#define NOCSPTRS ((128 / sizeof(void *)) - 3)
|
||||
|
||||
/*
|
||||
* A summary of contiguous blocks of various sizes is maintained
|
||||
@ -141,6 +143,18 @@
|
||||
#define MINFREE 8
|
||||
#define DEFAULTOPT FS_OPTTIME
|
||||
|
||||
/*
|
||||
* Grigoriy Orlov <gluk@ptci.ru> has done some extensive work to fine
|
||||
* tune the layout preferences for directories within a filesystem.
|
||||
* His algorithm can be tuned by adjusting the following parameters
|
||||
* which tell the system the average file size and the average number
|
||||
* of files per directory. These defaults are well selected for typical
|
||||
* filesystems, but may need to be tuned for odd cases like filesystems
|
||||
* being used for sqiud caches or news spools.
|
||||
*/
|
||||
#define AVFILESIZ 16384 /* expected average file size */
|
||||
#define AFPDIR 64 /* expected number of files per directory */
|
||||
|
||||
/*
|
||||
* The maximum number of snapshot nodes that can be associated
|
||||
* with each filesystem. This limit affects only the number of
|
||||
@ -273,12 +287,15 @@ struct fs {
|
||||
/* these fields retain the current block allocation info */
|
||||
int32_t fs_cgrotor; /* last cg searched */
|
||||
void *fs_ocsp[NOCSPTRS]; /* padding; was list of fs_cs buffers */
|
||||
u_int8_t *fs_contigdirs; /* # of contiguously allocated dirs */
|
||||
struct csum *fs_csp; /* cg summary info buffer for fs_cs */
|
||||
int32_t *fs_maxcluster; /* max cluster in each cyl group */
|
||||
int32_t fs_cpc; /* cyl per cycle in postbl */
|
||||
int16_t fs_opostbl[16][8]; /* old rotation block list head */
|
||||
int32_t fs_snapinum[FSMAXSNAP];/* list of snapshot inode numbers */
|
||||
int32_t fs_sparecon[30]; /* reserved for future constants */
|
||||
int32_t fs_avgfilesize; /* expected average file size */
|
||||
int32_t fs_avgfpdir; /* expected # of files per directory */
|
||||
int32_t fs_sparecon[28]; /* reserved for future constants */
|
||||
int32_t fs_contigsumsize; /* size of cluster summary array */
|
||||
int32_t fs_maxsymlinklen; /* max length of an internal symlink */
|
||||
int32_t fs_inodefmt; /* format of on-disk inodes */
|
||||
|
||||
Loading…
Reference in New Issue
Block a user