update for 4.4BSD

SCCS-vsn: sys/ufs/lfs/README 7.6

diff --git a/usr/src/sys/ufs/lfs/README b/usr/src/sys/ufs/lfs/README
index 972851d..b968568 100644 (file)
--- a/usr/src/sys/ufs/lfs/README
+++ b/usr/src/sys/ufs/lfs/README
@@ -1,29 +1,17 @@
-#      @(#)README      7.5 (Berkeley) %G%
+#      @(#)README      7.6 (Berkeley) %G%

 
 

-The file system is reasonably stable, but incomplete.  There is no cleaner
-on the 4.4BSD-Alpha tape.  Therefore, LFS is currently a "write-once" file
-system.  The cleaner system calls are all implemented and appear to work,
-although there are places where performance can be improved dramatically
-(see comments in lfs_syscalls.c).
+The file system is reasonably stable, but incomplete.  There are
+places where cleaning performance can be improved dramatically (see
+comments in lfs_syscalls.c).  For details on the implementation,
+performance and why garbage collection always wins, see Dr. Margo
+Seltzer's thesis available for anonymous ftp from toe.cs.berkeley.edu,
+in the directory pub/personal/margo/thesis.ps.Z, or the January 1993
+USENIX paper.

 
 Missing Functionality:
 
 Missing Functionality:

-       We currently do no block accounting when blocks are written.  Since
-       allocation is not performed until blocks in the buffer cache are
-       written to disk, it is possible to return success on a write, only
-       to discover later that there is insufficient space get the block
-       on disk.
-
-       We intend to support multiple block sizes rather than fragments.
-       This is not implemented.
-
-       Since blocks are laid out contiguously, we can miss rotations reading
-       sequentially.  We need to read in contiguous blocks to avoid that.
-       See McVoy's Winter 1991 Usenix paper for details on how to do that.
+       Multiple block sizes and/or fragments are not yet implemented.

 
 ----------
 
 ----------

-Design Details (a more complete design has been submitted to the January 1993
-Usenix Conference):
-

 The disk is laid out in segments.  The first segment starts 8K into the
 disk (the first 8K is used for boot information).  Each segment is composed
 of the following:
 The disk is laid out in segments.  The first segment starts 8K into the
 disk (the first 8K is used for boot information).  Each segment is composed
 of the following: