K 10
svn:author
V 6
msmith
K 8
svn:date
V 27
1998-11-02T23:28:11.000000Z
K 7
svn:log
V 677
Implement a simple LRU block cache.  By default this is initialised to 16k,
and will bypass transfers for more than 8k.  Blocks are invalidated after
2 seconds, so removable media should not confuse the cache.

The 8k threshold is a compromise; all UFS transfers performed by
libstand are 8k or less, so large file reads thrash the cache.
However many filesystem metadata operations are also performed using
8k blocks, so using a lower threshold gives poor performance.

Those of you with an eye for cache algorithms are welcome to tell me
how badly this one sucks; you can start with the 'bcachestats' command
which will print the contents of the cache and access statistics.

END