abs%NetBSD.org@localhost (David Brownlee) writes:
How does the Chip RAM and 16 bit non-chip ram compare speedwise
to the local/zorro/ranger RAM?
This is from an A3000 with CyberStorm Mk2 accelerator board.
fast $086F8000 -> 32bit "local" RAM on the accelerator board
user $07010000 -> 32bit "local" RAM on the motherboard
chip $000B0000 -> 32bit Chip RAM
rom $00F80000 -> shadow copy of the kickstart ROM
BusSpeedTest 0.19 (mlelstv) Buffer: 262144 Bytes, Alignment: 32768
========================================================================
memtype addr op cycle calib bandwidth
fast $086F8000 readw 71.5 ns normal 28.0 * 10^6 byte/s
fast $086F8000 readl 121.7 ns normal 32.9 * 10^6 byte/s
fast $086F8000 readm 121.4 ns normal 33.0 * 10^6 byte/s
fast $086F8000 writew 86.9 ns normal 23.0 * 10^6 byte/s
fast $086F8000 writel 174.7 ns normal 22.9 * 10^6 byte/s
fast $086F8000 writem 174.3 ns normal 22.9 * 10^6 byte/s
user $07010000 readw 159.3 ns normal 12.6 * 10^6 byte/s
user $07010000 readl 299.0 ns normal 13.4 * 10^6 byte/s
user $07010000 readm 298.8 ns normal 13.4 * 10^6 byte/s
user $07010000 writew 254.5 ns normal 7.9 * 10^6 byte/s
user $07010000 writel 511.8 ns normal 7.8 * 10^6 byte/s
user $07010000 writem 507.5 ns normal 7.9 * 10^6 byte/s
chip $000B0000 readw 1052.4 ns normal 1.9 * 10^6 byte/s
chip $000B0000 readl 1051.8 ns normal 3.8 * 10^6 byte/s
chip $000B0000 readm 1052.2 ns normal 3.8 * 10^6 byte/s
chip $000B0000 writew 568.4 ns normal 3.5 * 10^6 byte/s
chip $000B0000 writel 569.0 ns normal 7.0 * 10^6 byte/s
chip $000B0000 writem 569.0 ns normal 7.0 * 10^6 byte/s
rom $00F80000 readw 71.5 ns normal 28.0 * 10^6 byte/s
rom $00F80000 readl 122.6 ns normal 32.6 * 10^6 byte/s
rom $00F80000 readm 121.9 ns normal 32.8 * 10^6 byte/s
16bit Chip RAM (or non-Chip RAM or Ranger memory or 16bit Zorro-II RAM)
which is not present in this system is half the speed of 32bit Chip RAM.
But you see from the read speed above that there are artefacts caused
by the bus translator as CPU and graphics chips run on independent clocks.
So there is some variation depending on the exact hardware used.
Any kind of Chip RAM can get much slower, depending on graphics
chipset activity. Also, since Chip RAM doesn't support CAS it
must not be used as generic memory. This leaves three large groups:
local memory on the accelerator board ~10-60 MByte/s,
local 32bit memory on the motherboard ~10 Mbyte/s,
and 16bit memory (Zorro-II or ranger) ~3 MByte/s.