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1993-06-25
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License for FastCache(.68030)
-----------------------------
Any reference to FastCache refers to all the
FastCache's, irrespective of the processor that the
particular version was designed for.
FastCache is an unregistered trademark of Philip D'Ath.
1. COPYRIGHT: FastCache and the related
documentation are copyright. You may
not use or modify the programs or
documentation or any copy except as
expressly provided in this agreement
2. LICENSE: You have the non-exclusive right to
use any enclosed program. You may load
the program into your computer's
temporary memory (RAM). You may
physically transfer the program from one
computer to another. You may not
decompile, disassemble, reverse engineer,
modify or translate the program. After a
trial period of 3 months you must
register your copy of FastCache for each
machine that FastCache is run on.
All other rights and uses not
specifically granted in this license
relating to items created by the author
of FastCache are reserved by the author
of FastCache. Where clarification is
required of the above paragraph, the
author of FastCache shall decide the
clarification. Where such clarification
is deemed illegal, the latter sentence
will be withdrawn from this license.
3. BACKUP-UP AND TRANSFER: You may make any number of
physical backups of the program and
documentation provided the backups
remain in your immediate possession. You
must reproduce and include the copyright
notice on any backup copy. You may not
transfer or license the product to
another party.
FastCache by Philip D'Ath
December 14, 1992 Page 1 5:17AM
4. TERMS: This license is effective until
terminated. You may terminate it by
destroying the program and documentation
and all copies thereof. This license
will also terminate if you fail to comply
with any term or condition of this
Agreement. You agree upon such
termination you agree to destroy all
copies of the program and documentation.
FastCache is distributed under the
concept of Shareware.
5. PROGRAM DISCLAIMER: THE PROGRAMS ARE PROVIDED "AS IS"
WITHOUT WARRANTY OF ANY KIND, EITHER
EXPRESSED OR IMPLIED, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS FOR A
PARTICULAR PURPOSE. THE ENTIRE RISK AS
TO THE RESULTS AND PERFORMANCE OF ANY
PROGRAM IS ASSUMED BY YOU. Should the
program prove defective, you assume the
entire cost of all necessary servicing,
repair, or correction. Further, the
author of FastCache does not warrant,
guarantee, or make any representation
regarding the use of, or the results of
the use of, the program in terms of
corrections, accuracy, reliability,
currentness, or otherwise; and you rely
on the program and results solely at your
own risk.
6. LIMITATION OF LIABILITY: THE AUTHOR OF FastCache
ACCEPTS NO LIABILITY FOR ANY DAMAGE THAT
MAY RESULT FROM USE OF THIS PRODUCT AND
SHALL NOT IN ANY EVENT INCLUDE DAMAGES
FOR LOSS OF USE OR LOSS OF ANTICIPATED
PROFITS OR BENEFITS OR OTHER INCIDENTAL
OR CONSEQUENTIAL COSTS, EXPENSES OR
DAMAGES, INCLUDING WITHOUT LIMITATION ANY
DATA OR INFORMATION WHICH MAY BE LOST OR
RENDERED INACCURATE, EVEN IF THE AUTHOR
OF FastCache HAS BEEN ADVISED OF THE
POSSIBILITY OF SUCH DAMAGES.
FastCache by Philip D'Ath
December 14, 1992 Page 2 5:17AM
7. MISCELLANEOUS: This agreement represents the entire
understanding regarding the programs and
related documentation, and supersedes any
prior purchase order, communications or
representations. This agreement may only
be modified by a written amendment signed
by the author of FastCache. If any
provision of the agreement shall be
deemed unlawful, void, or for any reason,
unenforceable it shall be deemed separate
from, and shall in no way affect the
validity and enforceability of the
remaining provisions of the agreement.
This license agreement shall be governed by the
laws of the New Zealand.
8. The program License Agreement shall inure to the
benefit of the author of FastCache.
You should not be intimidated by this agreement. It is
expected that common sense should prevail.
This agreement is modelled after the copyright that
comes with the C compiler, DICE (by Matthew Dillon), and I
acknowledge this.
FastCache by Philip D'Ath
December 14, 1992 Page 3 5:17AM
Table of Contents
-----------------
License for FastCache(.68030) . . . . . . . . . . . . . 1
COPYRIGHT . . . . . . . . . . . . . . . . . . . . . 1
LICENSE . . . . . . . . . . . . . . . . . . . . . . 1
BACKUP-UP AND TRANSFER . . . . . . . . . . . . . . 1
TERMS . . . . . . . . . . . . . . . . . . . . . . . 2
PROGRAM DISCLAIMER . . . . . . . . . . . . . . . . 2
LIMITATION OF LIABILITY . . . . . . . . . . . . . . 2
MISCELLANEOUS . . . . . . . . . . . . . . . . . . . 3
Introduction . . . . . . . . . . . . . . . . . . . . . . 5
History . . . . . . . . . . . . . . . . . . . . . . 5
Features . . . . . . . . . . . . . . . . . . . . . 6
Requirements . . . . . . . . . . . . . . . . . . . . . . 7
Warnings . . . . . . . . . . . . . . . . . . . . . . . . 7
Installation . . . . . . . . . . . . . . . . . . . . . . 8
DEVICE . . . . . . . . . . . . . . . . . . . . . . 9
UNIT . . . . . . . . . . . . . . . . . . . . . . . 9
NO_UNIT_CHECK . . . . . . . . . . . . . . . . . . . 9
NUM_LINES . . . . . . . . . . . . . . . . . . . . . 9
LINE_SIZE . . . . . . . . . . . . . . . . . . . . . 10
DONOTWAIT . . . . . . . . . . . . . . . . . . . . . 10
WRITE_RETENTION_TIME . . . . . . . . . . . . . . . 10
QUIET_WRITE_TIME . . . . . . . . . . . . . . . . . 11
NO_CHIP . . . . . . . . . . . . . . . . . . . . . . 11
? . . . . . . . . . . . . . . . . . . . . . . . . . 11
Registration . . . . . . . . . . . . . . . . . . . . . . 12
FastCache by Philip D'Ath
December 14, 1992 Page 4 5:17AM
Introduction
------------
History:
In 1992 I came across a program called SmartDisk. This
program was a hard drive cache. After using this program for
a short time I was very impressed by the performance increase
it could give.
During that year I learnt about cache's at the
University of Waikato, and several caching algorithms. In
particular, I learned about direct map, set associative and
fully associative caches, and the merits of each.
A direct map cache is the easiest to implement, has a
low overhead, but can waste large chunks of the cache's
memory.
A set associate cache (which is what SmartDisk uses) is
a little smarter with its memory usage. Essentially, a set
associate cache is a whole lot of little direct map caches
combined. Obviously, a set associate cache is a little more
tricky to implement since several direct map caches have to
be managed.
The most complex of the three caching algorithms is a
fully associate cache. This has the greatest processing
overhead of the three, but results in much better cache
memory usage.
After having learned about these three particular
caching algorithms, and remembering what SmartDisk was like,
and that it used a set associate cache I decided to write a
hard drive cache that implemented the more difficult fully
associate cache algorithm. And I'm please to say, it came
out better that I expected. Additionally, a second algorithm
has to be used to determine what action should occur when a
cache miss occurs. I chose to implement an LRU (Least
recently Used) algorithm, as this is also one of the best
available.
FastCache by Philip D'Ath
December 14, 1992 Page 5 5:17AM
Features:
Below is some of the many features I have built into
FastCache.
* Fully associate cache (one of the best algorithms)
* LRU cache replacement policy (one of the best)
* Can handle multiple drives
* *Should* be able to handle removable media
* All cache settings are determined at run time
* Optional write retention
* Does not require large continuous chunks of memory
* Uses a hashing system to locate date (one of the best)
* Performs both forward and reverse prefetching
* Will utilize the blitter to move data, if possible
I have spared little in writing FastCache. It uses some
of the best algorithms (and more often than not, most complex
algorithms) for nearly everything.
FastCache by Philip D'Ath
December 14, 1992 Page 6 5:17AM
Requirements
------------
FastCache was design to be used under KS2.0. However, I
have used only KS1.3 functions. Because of this FastCache
may also work under KS1.3, but no guarantees. FastCache
should ONLY be used on devices that support seeking, like
hard drives.
FastCache works best with at least 512K of memory. It
runs acceptably in 256K, but don't expect big performance
gains. If you don't have this much memory free then stop
reading. FastCache is not for you.
With 512K FastCache performs nicely. However, the more
memory you give to FastCache, the better it goes.
Theoretically, there should be a point where if more memory
is added, performance decreases. However, because I have
used a hash searching system, I expect this limit would be
vary high (>10M for a 68030). As yet, I have been unable to
find this limit.
There are two version of FastCache supplied in this
archive. "FastCache.68000" is designed to run on a 68000, so
it suitable for all Amigas. "FastCache.68030" is designed
for a 68030 or better, and makes use of some of its extra
instructions.
Warnings
--------
I must give you some warnings as well. Because
FastCache uses RAM to store the most often used data, "bad"
things could happen if you have poorly behaved programs that
trash memory.
If you use write retention MAKE SURE YOU WAIT FOR THE
CACHE TO BECOME EMPTY BEFORE RESETTING YOUR MACHINE.
Otherwise, if data is waiting to be written out, and you
perform a reset before the cache is flushed, then the data
will be lost.
You should use FastCache with care if your hard drive
has errors on it. FastCache will warn you if an error
occurs, but it may be too late if you have write retention
enabled. The worst problem occurs when a write request is
made. If write retention is on FastCache *may* retend the
data in the cache (then again, it might write it straight to
disk). Then at some later stage it may write it to the
disk. If an error occurs FastCache can not report it to the
program that made the request, because it would have already
been acknowledged. If this occurs FastCache will give you an
error (it pops up a little requester), but there is little
that can be done.
FastCache by Philip D'Ath
December 14, 1992 Page 7 5:17AM
Installation
------------
FastCache can be run from either WorkBench or the CLI.
For KS2.0 users, I recommend placing it in your WBStartup
drawer.
When started from WorkBench, the parameters are
extracted from the ToolTypes fields. When started from CLI
that parameters are obtained from after the command.
Invoke FastCache once to start it going. Invoke it
again with the same parameters to make it quit. FastCache
will come up with a requester asking you if you want it to
quit. You must acknowledge this before it actually will.
Quitting automatically flushes the cache first. Note that if
write retention is enabled it may take some time before this
requester appears.
An example parameter for a WorkBench start that goes in
the ToolTypes field is:
DEVICE=gvpscsi.device
The equivalent parameter for a CLI start is:
FastCache -DEVICE=gvpscsi.device
All CLI parameters have a "-" inserted before the
parameter name.
Note that all parameters have default values, and hence
all are optional. However, some settings (e.g. DEVICE) may
have to be specified for you system.
FastCache by Philip D'Ath
December 14, 1992 Page 8 5:17AM
The available parameters and their descriptions are:
DEVICE=<devicename> default: gvpscsi.device
Example: DEVICE=gvpscsi.device
Description: This specifies the name of the device that is
to be cached.
UNIT=<unit number> default: 0
Example: UNIT=0
Description: This parameter specifies which unit number to
cache. Each drive will have a unit number.
The first drive is usually unit 0. Note that
a Hard Drive may have many partitions on it.
This unit number does not refer to those
partitions, but to the drive itself. All
partitions on a selected drive will be cached.
Warning: There is no element in a device structure to
determine which unit is being talked to.
Hence this parameter may be unreliable on some
systems. It has been tested on a GVP SCSI
interface with no problems. If you have
multiple drives, use FastCache with care to
begin with.
See Also: NO_UNIT_CHECK
NO_UNIT_CHECK default: -
Example: NO_UNIT_CHECK
Description: This parameter is designed for those Hard
Drive cards that the unit selection above does
not work on. ONLY USE IT IF YOU HAVE ONE HARD
DRIVE. This option tells FastCache not to try
and check IO requests for the unit they are
destined for.
NUM_LINES default: 256
Example: NUM_LINES=256
Description: This tells FastCache how many lines it should
allocate for the cache. I wont give you the
technical description, but in a multitasking
environment several programs could be wanting
data from several different places on the
disk. To enable effective management of the
cache (especially with regard to prefetching)
each of these requests are assigned a line.
Several lines can also be combined to form a
longer line as well for programs which make
many requests for data in a similar place.
This parameter can be any number greater than
or equal to 1. If you want a bigger cache
this should be one of the first parameters
that you increase.
NOTE: To calculate the size of the cache multiply
the number of lines by the line size by the
block size (512).
FastCache by Philip D'Ath
December 14, 1992 Page 9 5:17AM
LINE_SIZE default: 4
Example: LINE_SIZE=4
Description: This is the line size for the cache. I wont
give a technical description, but this
essentially controls how much pre-fetching is
done. For a device with a slow seek time use
a small line size. For a fast seeking device
a bigger line size can help. Note, if the
data on your drive is not contiguous then use
a small line size (like 4, or even 2). This
parameter MUST be a power of two (e.g. 2, 4,
8) and must be greater than or equal to 1. If
you supply a parameter which is not a power of
two, it will be rounded to a power of two.
Note that both reverse and forward prefetching
is done once the direction of the read/write
operation is established (e.g. Try using
Aquarium and search backwards for something).
I recommend line sizes no larger than 8. To
get big caches try increasing the number of
lines.
NOTE: To calculate the size of the cache multiply
the number of lines by the line size by the
block size (512).
DONOTWAIT default: -
Example: DONOTWAIT
Description: This is actually a WorkBench parameter, and
tells WorkBench not to wait for the program to
finish. This is recommended for WorkBench
starts.
WRITE_RETENTION_TIME default: 60
Example: WRITE_RETENTION_TIME=60
Description: This controls the MAXIMUM amount of time (in
seconds) that data which has been changed can
be held in the cache. To disable write
retention set this parameter to 0.
WARNING: If you want to reset your computer you must
wait the smaller of WRITE_RETENTION_TIME or
QUIET_WRITE_TIME (in the case that no IO is
occurring) BEFORE you can safely reset your
computer. Note that if you try to quit
FastCache it may take WRITE_RETENTION_TIME
before FastCache responds and asks you if you
really want to quit.
See Also: QUIET_WRITE_TIME
FastCache by Philip D'Ath
December 14, 1992 Page 10 5:17AM
QUIET_WRITE_TIME default: 1
Example: QUIET_WRITE_TIME=1
Description: This parameter only takes effect when write
retention is enabled and there is data in the
cache that has been changed. If this is the
case, then FastCache must at some time write
the changed data back to the disk. During
disk activity there often comes time when no
IO occurs because a program is working
something out. This is an ideal time to
output changed data, since no other IO request
will be impeded. This parameter monitors the
time (in seconds) since the last IO request,
and if there has been no IO requests for the
specified amount of time the changed data is
written back to the disk in the hope that
there will be no other disk IO requests during
that time.
WARNING: If you want to reset your computer you must
wait the smaller of WRITE_RETENTION_TIME or
QUIET_WRITE_TIME (in the case that no IO is
occurring) BEFORE you can safely reset your
computer.
NO_CHIP default: -
Example: NO_CHIP
Description: Not all hard drive controllers are capable to
writing to all of memory. Hence, FastCache
normally allocates a small CHIP buffer, and
all IO requests that FastCache makes to the
hard drive are done through this buffer (and
the blitter will be utilized, if possible).
On cards that can write to all of memory this
parameter can be specified to prevent the CHIP
memory buffer being used. In practice, I have
found that this gives little performance
difference.
? default: -
Example: ?
Description: Displays help.
FastCache by Philip D'Ath
December 14, 1992 Page 11 5:17AM
Registration
------------
FastCache is released under the concept of Shareware.
If after a 3 month trial period you still wish to use
FastCache I would appreciate $20 (in cheque form) in either
NZ, Australian or American dollars. The Australian and US
prices (both being $20) may seem artificially higher, but
this covers the cost of changing the funds to $NZ.
By registering you may not necessarily gain anything.
However, if I get enough support I will improve (yes, I can
improve it further) FastCache. If this is the case, I will
attempt to notify all registered users.
Please send this completed form to:
Philip D'Ath
9 Elmwood Crescent,
Pukete,
Hamilton,
NEW ZEALAND.
Name: _________________________________________________
Address: _________________________________________________
_________________________________________________
_________________________________________________
_________________________________________________
Hard Drive Controller: __________________________________
Funds Enclosed: $ ___________
The most important thing to add/change to/in FastCache is:
______________________________________________________
______________________________________________________
______________________________________________________
Comments:
______________________________________________________
______________________________________________________
______________________________________________________
______________________________________________________
FastCache by Philip D'Ath
December 14, 1992 Page 12 5:17AM
