* about interlagos
@ 2012-06-16 6:41 Mahmood Naderan
2012-06-16 9:20 ` Clemens Ladisch
0 siblings, 1 reply; 3+ messages in thread
From: Mahmood Naderan @ 2012-06-16 6:41 UTC (permalink / raw)
To: linux-kernel
There are three opteron processors with the cpuid that I paste below:
model name : AMD Opteron(tm) Processor 6136 (magny core, 8)
cpu MHz : 800.000
cache size : 512 KB
bogomips : 4800.20
model name : AMD Opteron(tm) Processor 6174 (magny core, 12)
cpu MHz : 800.000
cache size : 512 KB
bogomips : 4400.13
model name : AMD Opteron(TM) Processor 6274 (interlagos, 16)
cpu MHz : 1400.000
cache size : 2048 KB
bogomips : 4399.97
As you can see, although interlagos is the newest one which has higher cpu
clock rate and higher cache size, the bogomips of interlagos is the lowest!
I read that bogomips is not a true measurement, but it senses as a speed meter.
Any idea?
~MN
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: about interlagos
2012-06-16 6:41 about interlagos Mahmood Naderan
@ 2012-06-16 9:20 ` Clemens Ladisch
2012-06-16 9:32 ` Mahmood Naderan
0 siblings, 1 reply; 3+ messages in thread
From: Clemens Ladisch @ 2012-06-16 9:20 UTC (permalink / raw)
To: Mahmood Naderan; +Cc: linux-kernel
Mahmood Naderan wrote:
> As you can see, although interlagos is the newest one which has higher cpu
> clock rate and higher cache size, the bogomips of interlagos is the lowest!
> I read that bogomips is not a true measurement,
Indeed it is not.
> but it senses as a speed meter.
It measures the speed of one particular delay loop. Because such a busy
loop is pretty much the silliest thing you could do to a CPU, it does
not make sense to use it to measure overall CPU speed, or to compare
different microarchitectures.
> Any idea?
If you want to know how fast your code will execute, you have to measure
that code. If you are too lazy to do this, search for a benchmark that
represents that code well; for general-purpose code, the gcc part of the
SPEC CPU benchmark probably comes closest.
Regards,
Clemens
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: about interlagos
2012-06-16 9:20 ` Clemens Ladisch
@ 2012-06-16 9:32 ` Mahmood Naderan
0 siblings, 0 replies; 3+ messages in thread
From: Mahmood Naderan @ 2012-06-16 9:32 UTC (permalink / raw)
To: Clemens Ladisch; +Cc: linux-kernel
Thanks
// Naderan *Mahmood;
----- Original Message -----
From: Clemens Ladisch <clemens@ladisch.de>
To: Mahmood Naderan <nt_mahmood@yahoo.com>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Sent: Saturday, June 16, 2012 1:50 PM
Subject: Re: about interlagos
Mahmood Naderan wrote:
> As you can see, although interlagos is the newest one which has higher cpu
> clock rate and higher cache size, the bogomips of interlagos is the lowest!
> I read that bogomips is not a true measurement,
Indeed it is not.
> but it senses as a speed meter.
It measures the speed of one particular delay loop. Because such a busy
loop is pretty much the silliest thing you could do to a CPU, it does
not make sense to use it to measure overall CPU speed, or to compare
different microarchitectures.
> Any idea?
If you want to know how fast your code will execute, you have to measure
that code. If you are too lazy to do this, search for a benchmark that
represents that code well; for general-purpose code, the gcc part of the
SPEC CPU benchmark probably comes closest.
Regards,
Clemens
^ permalink raw reply [flat|nested] 3+ messages in thread
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