Summary: Memory Interleaving on the E4500 server

From: Tony Magtalas <ttk67_at_yahoo.com>
Date: Tue Jul 16 2002 - 02:27:45 EDT
Thanks to:

Kevin Buterbaugh <Kevin.Buterbaugh@lifeway.com>
Tony Walsh-Field Service Engineer"<Tony.Walsh@Sun.COM>
system administration account" <sysadmin@astro.su.se>
"Scott Howard" <scott@doc.net.au>
"Bob Rahe" <bob@dtcc.edu>

Almost everyone thinks that memory interleave works
in the "power of two" fashion. As Tony Walsh put it:

Memory interleave happens on banks in 'powers of 2'
counts. In other words, 1, 2, 4, or 8 banks are put
together to make an interleaved bank. So what you have
is the correct layout. You would need another
CPU/memory board to change the pattern.

Kevin Buterbaugh offered a different perspective:
I don't think you will.  I've got an almost identical
situation with a E3000.  I'm getting a combination of
4-way and 2-way interleaving.  I can't find anything
on SunSolve to indicate that 6-way interleaving is 
possible(it refers to powers of 2).

However, in "System Performance Tuning, 2nd edition"
by Gian-Paolo D. Musumeci and Mike Loukides,
Gian-Paolo (a Sun engineer, BTW) says that the Ultra
Enterprise line will do 6-way interleaving.  I've
e-mailed him about
that, but haven't heard back from him yet.

If you find out that it is possible, I'd like to know
how it's done...

Yet another feedback from sysadmin@astro.su.se:
It looks like the interleave must be a power of two
(1-way, 2-way, 4-way or 8-way). I got a failed DIMM in
a SunFire 6800 today, and that broke the usual 8-way
interleaving into a mix of 4-, 2- and 1-way. One would
have hoped for a 6-way, but no. I can't give you a
rationale for this design, but it seems to apply to a
number of Sun's midrange servers.

(Actually, on second thought it seems to me that 6-way
interleaves would require slightly more elaborate
logic in the MMU, since you can't just shuffle address
bits any more but must do either a table lookup or a
calculation. Maybe that's the reason.)

----

Original question:

I have an E4500 with 3 CPU/Memory boards, each
populated with identical memory SIMMS and CPU modules
(each SIMM is 256 MB, each bank = 2GB) CPU are all
400Mhz modules with 8 MB Ecache.

Question:

Should I get 6-way interleave memory for this
configuration ( 6 memory banks)

Here is what I get when I run "prtdiag" command:
(I got a mixture of 4 way and 2 way interleave)

Please reply. I will summarize
Tony

----
output of "prtdiag -v" :

System Configuration:  Sun Microsystems  sun4u 8-slot
Sun Enterprise E4500/E5500
System clock frequency: 100 MHz
Memory size: 12288Mb

========================= CPUs
=========================

                    Run   Ecache   CPU    CPU
Brd  CPU   Module   MHz     MB    Impl.   Mask
---  ---  -------  -----  ------  ------  ----
 0     0     0      400     8.0   US-II    10.0
 0     1     1      400     8.0   US-II    10.0
 2     4     0      400     8.0   US-II    10.0
 2     5     1      400     8.0   US-II    10.0
 4     8     0      400     8.0   US-II    10.0
 4     9     1      400     8.0   US-II    10.0


========================= Memory
=========================

                                              Intrlv. 
Intrlv.
Brd   Bank   MB    Status   Condition  Speed   Factor 
 With
---  -----  ----  -------  ----------  -----  ------- 
-------
 0     0    2048   Active      OK       60ns    4-way 
   A
 0     1    2048   Active      OK       60ns    4-way 
   A
 2     0    2048   Active      OK       60ns    4-way 
   A
 2     1    2048   Active      OK       60ns    2-way 
   B
 4     0    2048   Active      OK       60ns    4-way 
   A
 4     1    2048   Active      OK       60ns    2-way 
   B

========================= IO Cards
=========================

     Bus   Freq
Brd  Type  MHz   Slot  Name                           
 
======================

Most recent AC Power Failure:
=============================
Wed May 15 10:40:41 2002


========================= Environmental Status
=========================
Keyswitch position is in Normal Mode
System Power Status: Redundant
System LED Status:    GREEN     YELLOW     GREEN
Normal                 ON        OFF       BLINKING


Fans:
-----
Unit   Status
----   ------
Rack    OK
Key     OK
AC      OK

System Temperatures (Celsius):
------------------------------
Brd   State   Current  Min  Max  Trend
---  -------  -------  ---  ---  -----
 0      OK       30     27   34  stable
 1      OK       37     36   37  stable
 2      OK       29     25   32  stable
 3      OK       39     38   41  stable
 4      OK       27     23   30  stable
 5      OK       34     32   35  stable
 7      OK       39     39   41  stable
CLK     OK       27     26   28  stable


Power Supplies:
---------------
Supply                        Status
---------                     ------
0                                OK
1                                OK
2                                OK
3                                OK
PPS                              OK
    System 3.3v                  OK
    System 5.0v                  OK
    Peripheral 5.0v              OK
    Peripheral 12v               OK
    Auxilary 5.0v                OK
    Peripheral 5.0v precharge    OK
    Peripheral 12v precharge     OK
    System 3.3v precharge        OK
    System 5.0v precharge        OK
AC Power                         OK


========================= HW Revisions
=========================

ASIC Revisions:
---------------
Brd  FHC  AC  SBus0  SBus1  PCI0  PCI1  FEPS  Board
Type      Attributes
---  ---  --  -----  -----  ----  ----  ---- 
----------      ----------
 0    1    5                                  CPU     
       100MHz Capable
 1    1    5    1      1                 22  
Dual-SBus-SOC+  100MHz Capable
 2    1    5                                  CPU     
       100MHz Capable
 3    1    5    1      1                 22  
Dual-SBus-SOC+  100MHz Capable
 4    1    5                                  CPU     
       100MHz Capable
 5    1    5    1      1                 22  
Dual-SBus-SOC+  100MHz Capable
 7    1    5                 4     4     c1   Dual-PCI
       100MHz Capable

System Board PROM revisions:
----------------------------
Board  0:   OBP   3.2.29 2001/06/18 17:28   POST 
3.9.29 2001/06/18 17:50
Board  1:   FCODE 1.8.29 2001/06/18 17:26   iPOST
3.4.29 2001/06/18 17:49
Board  2:   OBP   3.2.29 2001/06/18 17:28   POST 
3.9.29 2001/06/18 17:50
Board  3:   FCODE 1.8.29 2001/06/18 17:26   iPOST
3.4.29 2001/06/18 17:49
Board  4:   OBP   3.2.29 2001/06/18 17:28   POST 
3.9.29 2001/06/18 17:50
Board  5:   FCODE 1.8.29 2001/06/18 17:26   iPOST
3.4.29 2001/06/18 17:49
Board  7:   FCODE 1.8.29 2001/06/18 17:25   iPOST
3.0.29 2001/06/18 17:49
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Received on Tue Jul 16 02:36:18 2002

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