mike.mccarty@xxxxxxxxxxxxx wrote:
Jim Cornette wrote:
John Summerfied wrote:
Jeff Vian wrote:
Exactly, and IIRC the filesystem knows that if it needs X amount of
space for a file, then Y number of inodes are marked for use for that
file at the beginning. Thus space allocated is as contiguous as is
efficient for read/write on the disk.
If "the filesystem knows that if it needs X amount of space for a
file," that implies there's a way of telling it that.
How's that done? I don't recall any system call for *x (there is one
for OS/2), and one could do it in JCL in IBM's OS in the 60s), but
in the *x world I've never seen a way to do it.
Since the discussions regarding fragmentation on ext3 filesystems was
pretty long running. I decided to try
filefrag /usr/bin/* |sort |grep 'would be'
and the output showed a lot of fragmentation. One of the files was up
to 45.
On my system I did this...
# filefrag /usr/bin/* | sort -k2 -nr | grep 'would be'
Here're the first few entries...
/usr/bin/emacs: 248 extents found, perfection would be 1 extent
/usr/bin/emacs-21.3: 248 extents found, perfection would be 1 extent
/usr/bin/kermit: 80 extents found, perfection would be 1 extent
/usr/bin/kbabel: 45 extents found, perfection would be 1 extent
/usr/bin/ddd: 45 extents found, perfection would be 1 extent
/usr/bin/gthumb: 41 extents found, perfection would be 1 extent
/usr/bin/gdbtui: 36 extents found, perfection would be 1 extent
/usr/bin/elinks: 30 extents found, perfection would be 1 extent
/usr/bin/iniomega: 22 extents found, perfection would be 1 extent
/usr/bin/kpersonalizer: 21 extents found, perfection would be 1 extent
/usr/bin/artsd: 21 extents found, perfection would be 1 extent
/usr/bin/artscat: 20 extents found, perfection would be 1 extent
/usr/bin/kiconedit: 19 extents found, perfection would be 1 extent
/usr/bin/glade-2: 19 extents found, perfection would be 1 extent
/usr/bin/karm: 18 extents found, perfection would be 1 extent
/usr/bin/dia: 18 extents found, perfection would be 1 extent
/usr/bin/designer3: 18 extents found, perfection would be 1 extent
/usr/bin/designer: 18 extents found, perfection would be 1 extent
/usr/bin/kppplogview: 16 extents found, perfection would be 1 extent
/usr/bin/kfontinst: 16 extents found, perfection would be 1 extent
/usr/bin/civclient-xaw: 15 extents found, perfection would be 1 extent
/usr/bin/cdrecord: 15 extents found, perfection would be 1 extent
/usr/bin/knewstickerstub: 14 extents found, perfection would be 1 ext
Surely those who argue that ext3 does not get fragmented
during install don't think that 248 extents is "not
significant fragmentation".
I assure you that I have done nothing on my system to try to
fragment emacs.
Mike
--
p="p=%c%s%c;main(){printf(p,34,p,34);}";main(){printf(p,34,p,34);}
This message made from 100% recycled bits.
You have found the bank of Larn.
I can explain it for you, but I can't understand it for you.
I speak only for myself, and I am unanimous in that!
Yes, but...
[root@bend ~]# filefrag /bin/* | sort -k2 -nr | grep 'would be'
/bin/netstat: 2 extents found, perfection would be 1 extent
/bin/login: 2 extents found, perfection would be 1 extent
Files that are frequently updated will often have some level of
fragmentation. Files that are relatively unchanged tend to be in a
single extent. Also, the stuff in /bin will generally be small, tight,
command line programs. A quick perusal of those listed in your example
shows a number of graphical interface programs that are anything but
small and don't even get me started about the size of emacs (the
probability of change to a program is very directly related to the size
of the program).
Cheers,
Dave
