Alpha Emulator performance Prepare text for printer

How to improve performance

We have created special drivers to optimize the communications between OpenVMS and CHARON-AXP. The benefits this special software offers outweighs the principle that virtual hardware is totally independent of the operating system it supports. You decide whether to use it or not, it can be installed and de-installed as desired.

Every CHARON-AXP installation (version 2 and later) comes with a disk image that contains specific programs and drivers that can provide additional performance. The disk is called "Drivers.vdisk" and is located in the Charon-AXP installation directory.

Mount the disk like this : $ Mount dka100: tools

It contains 5 directories:
- Bypass (contains the bypass driver)
- Digiboard (contains the driver for the PBXDA serial board)
- Idle (contains the Idle package)
- PCSI (contains upgrade for PCSI for older VMS versions)
- SCSI (contains a SCSI patch for VMS 6.2-1h3 that solves large disk problems)

Idle

Idle is a product for OpenVMS that significantly reduces the CHARON-AXP host CPU usage whenever a
VMS system running on CHARON-AXP is idle. Idle stalls the emulated
CPU when it detects an OpenVMS idle condition. While Idle is running the emulated CPU
consumes, on average, less host system CPU time. It is not recommended to employ
Idle in real-time process control environments.

Installing Idle:

$ Mount dka100: tools
$ Product Install /source=dka100:[idle] *

The following product has been selected:
SRI AXPVMS IDLE V1.2 Layered Product

Do you want to continue? [YES]

Follow the instructions the Idle program will be loaded automatically.

Bypass

Bypass is a special emulated SCSI like disk controller that has never existed in any DEC system.
It is a controller designed for the Charon-AXP product to get as less overhead as possible and get the highest transfer rates. Of course since this controller never existed VMS does not have a driver for it.
Therefore we developed a VMS driver that handles this controller.

Installing bypass driver:

$ Mount dka100: tools
$ Product install /source=dka100:[bypass]

The following product has been selected:
SRI AXPVMS CHARON_DISK V1.0 Layered Product

Do you want to continue? [YES]

Follow the instructions and the driver will be installed.

Configuring the bypass in the configuration file:

To enable the bypass add "bypass" to the loading of a SCSI controller:

Load 1 PK bypass

Please note that on bypass enabled controllers only disks will work and no tapes or other devices.

In addition to the faster throughput that can be achieved with this bypass enabled, it provides an option to change the device name in VMS by loading a different controller
PK "SCSI"
PQ "IDE"
PU "MSCP"
PI  "DSSI"
PG "FIBER CHANNEL"

Load 1 PG bypass

Load DGA100
DGA100.image="C:\Disks\disk1.vdisk"
Load DGA200
DGA200.image="\\.\Physicaldrive1"
Load DGA300
DGA300.image="\\.\SCSI4: 0 2 0"

In VMS the device will turn up as a fiber channel disk : $1$DGA100: and can be used for Mixed fiber channel clustering with real Alpha systems.

Digiboard

The PBXDA serial line controller needs a VMS driver in order to operate.

Installing the PBXDA driver:

$ Mount dka100: tools
$ Product install /source=dka100:[digiboard] *

1 - DIGI AXPVMS DGDRIVER D1.3-0 Layered Product
2 - DIGI AXPVMS DGDRIVER_7 D1.3-0 Layered Product
3 - DIGI AXPVMS DGDRIVER_8 D1.5-0 Layered Product
4 - All products listed above
5 - Exit

Choose one or more items from the menu separated by commas:

For VMS 6.2x choose option 1, VMS 7.x option 2, VMS8.x option 3
Follow the instructions on the screen to complete the installation.