* 8270 performance
@ 2003-12-08 19:50 Jaap-Jan Boor
2003-12-08 20:51 ` Ricardo Scop
0 siblings, 1 reply; 4+ messages in thread
From: Jaap-Jan Boor @ 2003-12-08 19:50 UTC (permalink / raw)
To: linuxppc-embedded
Hi,
I've a modified 2.4.22 kernel built with gcc 3.3.2
running on a 8270 system here and see the following
cpuinfo:
# cat /proc/cpuinfo
cpu : 82xx (Hip7)
core clock : 266 MHz
CPM clock : 166 MHz
bus clock : 66 MHz
revision : 32.17 (pvr 8082 2011)
bogomips : 175.71
I would expect the bogomips number
to be somewhere near the core clock
(like 8xx).
Any experience? Thanks
Jaap-Jan
---
J.G.J. Boor Anton Philipsweg 1
Software Engineer 1223 KZ Hilversum
AimSys bv tel. +31 35 689 1941
Postbus 2194, 1200 CD Hilversum mailto:jjboor@aimsys•nl
** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: 8270 performance
2003-12-08 19:50 8270 performance Jaap-Jan Boor
@ 2003-12-08 20:51 ` Ricardo Scop
0 siblings, 0 replies; 4+ messages in thread
From: Ricardo Scop @ 2003-12-08 20:51 UTC (permalink / raw)
To: Jaap-Jan Boor, linuxppc-embedded
On Monday 08 December 2003 17:50, Jaap-Jan Boor wrote:
> Hi,
>
> I've a modified 2.4.22 kernel built with gcc 3.3.2
> running on a 8270 system here and see the following
> cpuinfo:
>
> # cat /proc/cpuinfo
> cpu : 82xx (Hip7)
> core clock : 266 MHz
> CPM clock : 166 MHz
> bus clock : 66 MHz
> revision : 32.17 (pvr 8082 2011)
> bogomips : 175.71
>
> I would expect the bogomips number
> to be somewhere near the core clock
> (like 8xx).
Well, I think the numbers are pretty fair, assuming that the bogomips number
reflect a certain amount of external memory accesses at 66 MHz external bus
clock.
>
> Any experience? Thanks
Yes, we have a 8250' powered custom board running at:
- cpu_clk 196608000, cpm_clk 163840000, bus_clk 65536000
Our ported good old PPCBoot 1.1.5 reports:
CPU: MPC8260 (Rev 14, Mask unknown [immr=0x0062,k=0x002d]) at 196.608 MHz
And the 2.4.21 kernel:
Calibrating delay loop... 130.66 BogoMIPS
HTH,
-Scop.
>
> Jaap-Jan
>
> ---
> J.G.J. Boor Anton Philipsweg 1
> Software Engineer 1223 KZ Hilversum
> AimSys bv tel. +31 35 689 1941
> Postbus 2194, 1200 CD Hilversum mailto:jjboor@aimsys•nl
>
>
** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/
^ permalink raw reply [flat|nested] 4+ messages in thread
* RE: 8270 performance
@ 2003-12-08 21:11 Jean-Denis Boyer
2003-12-09 7:35 ` Jaap-Jan Boor
0 siblings, 1 reply; 4+ messages in thread
From: Jean-Denis Boyer @ 2003-12-08 21:11 UTC (permalink / raw)
To: Ricardo Scop, Jaap-Jan Boor; +Cc: linuxppc-embedded
Ricardo,
Jaap-Jan,
> > I would expect the bogomips number
> > to be somewhere near the core clock
> > (like 8xx).
>
> Well, I think the numbers are pretty fair, assuming that the
> bogomips number
> reflect a certain amount of external memory accesses at 66
> MHz external bus
> clock.
It has more to do with pipelining!
Hopefully, there ain't any memory access during calibration...
(except, of course, when the instruction cache is disabled!)
I didn't look at the documentation, but the execution of a branch probably occurs later in the pipeline of a 8260 than for the 860. It probably looses one more cycle. The calibration relies on the execution speed of function __delay (arch/ppc/kernel/misc.S), which loops on a branch instruction 'bdnz'.
Fortunately, the number of bogomips will increase linearly with the core clock.
(These are approximations)
For 8260:
200MHz => 66M bdnz per second => 133BogoMips
266 => 88M => 176
400 => 133M => 266
For 860:
50MHz => 25M bdnz per second => 50BogoMips
Regards,
--------------------------------------------
Jean-Denis Boyer, Eng.
M5T Centre d'Excellence en Télécoms Inc.
4283 Garlock Street
Sherbrooke (Québec)
J1L 2C8 CANADA
(819)829-3972 x241
--------------------------------------------
** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: 8270 performance
2003-12-08 21:11 Jean-Denis Boyer
@ 2003-12-09 7:35 ` Jaap-Jan Boor
0 siblings, 0 replies; 4+ messages in thread
From: Jaap-Jan Boor @ 2003-12-09 7:35 UTC (permalink / raw)
To: Jean-Denis Boyer; +Cc: linuxppc-embedded, Ricardo Scop
On 8-dec-03, at 22:11, Jean-Denis Boyer wrote:
>
> Ricardo,
> Jaap-Jan,
>
>>> I would expect the bogomips number
>>> to be somewhere near the core clock
>>> (like 8xx).
>>
>> Well, I think the numbers are pretty fair, assuming that the
>> bogomips number
>> reflect a certain amount of external memory accesses at 66
>> MHz external bus
>> clock.
>
> It has more to do with pipelining!
> Hopefully, there ain't any memory access during calibration...
> (except, of course, when the instruction cache is disabled!)
>
> I didn't look at the documentation, but the execution of a branch
> probably occurs later in the pipeline of a 8260 than for the 860. It
> probably looses one more cycle. The calibration relies on the
> execution speed of function __delay (arch/ppc/kernel/misc.S), which
> loops on a branch instruction 'bdnz'.
>
> Fortunately, the number of bogomips will increase linearly with the
> core clock.
> (These are approximations)
>
> For 8260:
> 200MHz => 66M bdnz per second => 133BogoMips
> 266 => 88M => 176
> 400 => 133M => 266
>
> For 860:
> 50MHz => 25M bdnz per second => 50BogoMips
Ok, that's a nice explanation, thanks!
Jaap-Jan
>
>
> Regards,
> --------------------------------------------
> Jean-Denis Boyer, Eng.
> M5T Centre d'Excellence en Télécoms Inc.
> 4283 Garlock Street
> Sherbrooke (Québec)
> J1L 2C8 CANADA
> (819)829-3972 x241
> --------------------------------------------
** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/
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