[RC5] LIFO? Is this true?

Joe Zbiciak j-zbiciak1 at ti.com
Sat May 9 21:08:05 EDT 1998


'Paul West' said previously:
| 
| Ryan Anderson wrote:
| 
| > Wouldn't it be smart to have a separate buff-out for each 
| > block? 
| 
| No!   I sure don't want 1000 separate files in any directory.

Agreed.  Most filesystems (including the widely used FAT filesystem)
perform horribly when there's many files in a directory.

Many Unixes also bog down horribly, since most directory searches are
linear, and these long linear searches occur in kernel space --
effectively halting the whole system while the kernel looks for a
particular file to open.  (That's big part of why news servers which
store each article as a separate file get so heavily bogged down,
actually.  A news admin friend of mine showed me this first-hand.)

Some OS's use a more intelligent directory structure (eg. b-tree, or
other log(n) type of structure) that scales a little better with the
number of files, but that still doesn't make the each-block-gets-
a-file approach a win.  It's potentially easier to program, but it's
alot slower, no matter what.

Ironically, it's probably *not* easier to program portably either,
unless you make a separate "table of contents" file which tracks the
list of blocks--thus nullifying any benefit of storing one block per
file.  Reading directory entries tends to be rather OS-specific
(although POSIX has helped alot there).

Regards,

--Joe

-- 
  +------- Joseph Zbiciak ------+
  |- - - j-zbiciak1 at ti.com - - -|   without you, everything falls apart
  | -Texas Instruments, Dallas- |   without you, it's not as much fun
  |- - #include <disclaim.h> - -|   - NIN -      to pick up the pieces. 
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