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RE: Difference among CPU's



Hi,

The ETRAX 100LX V2 corrects a bug in the SDRAM interface of
ETRAX 100LX V1. There are no performance difference between
them. The easiest way to check if you have a V2 is to check
the text on the chip. If it is white and readable then you 
have a V2. If it is dark and almost invisible then you have
a V1. All ETRAX 100LX sold today are V2.

The bogomips have been discussed on this list before:

>It's because the number of instructions in the udelay asm-loop is not the
>same as the number in the i386 port (which the BogoMIPS presentation code
>is made for). So if we have 4 times as many instructions in one
>delay-loop, the bogomips value will be 4 times as low. But don't worry
>everything is still running at 100 MIPS, it's just the calculation of MIPS
>from delay loops per second which is broken.

>In the 2.0 port, we changed init/main.c to report using the proper
>multiplication value but in the 2.4 port we don't want to fiddle too much
>with non-arch code.

>Because of different loop behaviour the bogomips value does not accurately
>represent the CPU speed in many other linux ports either.

The kernel option can be set to ETRAX 100LX for both V1 and V2 but 
CONFIG_ETRAX100LX_V2 will give you more virtual memory. 
CONFIG_ETRAX100LX_V2 does not work for ETRAX 100LX V1.

Regards
/Mikael

-----Original Message-----
From: owner-dev-etrax@xxxxxxx.com]On">mailto:owner-dev-etrax@xxxxxxx.com]On
Behalf Of Dragan Stancevic
Sent: Tuesday, July 10, 2001 10:24 PM
To: dev-etrax
Subject: Difference among CPU's


Hi, I have two question for Axis guys

1.  What is the difference between the options for:
Etrax-100-LX-v1 and Etrax-100-LX-v2 and how do you know which CPU you have.
And does it give you any performance difference between the two?

2. When booting lx board the kernel prints out 
Calibrating delay loop... 33.17 BogoMIPS
I know for a fact that on the etrax100 it was saying that the udelay loop
was around 99.x BogoMIPS, now I am interested if the previous generation CPU is
only faster dooing udelay loop or is it faster in other respects too,
like executing other instructions. 99.x comes closer to 100MIPS processor
than 33 does. If for some reason the newgen processors are slower that would
be bad for our project, I'll do some performance testing on my own but I
wanted to get Axis' take on this first.

Thanks.

-- 
Peace can only come as a natural consequence
of universal enlightenment. -Dr. Nikola Tesla