From: Noel Bourke (cros13@gmail.com)
Date: Sun Jun 10 2007 - 07:11:42 ART
Core 2, no question. I'm simplifying a bit here with my explanation of why,
and glossing over quite a few issues.
Core 2 is a "four wide" architecture, meaning that it can issue four
instructions per clock cycle.
All of AMD's products are "3 wide". Predictability of instructions is
crucial here to gain maximum benefit.
Also due to the that emulation generates quite predictable instructions,
dynamips benefits from a longer pipeline.
This gives the core 2's 14-stage an advantage over the AMD 12-stage.
Its also the reason why the 31-stage p4 (netburst) did so well with binary
patching (e.g. VMware) and architecture emulation (e.g. PearPC).
The Core2's dynamically allocated shared cache also helps. More cache can be
used by a core running a dynamips
process which is under greater load (e.g. emulating say a hub router, or a
router running more protocols than the others).
AMD has the hypertransport bus and onboard memory controller which is not as
decisive an advantage as the core 2 cache.
A dynamips can also be aware of data loaded to the cache by a process
running on the other core which with a static image file like the ios image
You are using with dynamips can reduce the amount of times the process has
to access the drastically slower main memory.
So to simplify a bit further, say your dynamips process on one core is
running though the section of the ios image to send an ospf hello.
1.3 seconds later another dynamips process running on the other core has to
send a hello too, your AMD has to take a comparatively long
commute to the memory controller (yes even though the memory controller is
onboard its still further then the cache), and then an epic transcontinental
journey
to main memory.
For all it cares your other cpu cores cache could be in siberia instead of
right beside it on the die, its not even aware of its existence let alone
contents.
The AMD will probably have half or less cache then the core 2 regardless.
OK enough on the CPU. Core 2 it is then.
RAM....uhuh....ok....go for the fastest you can get (PC5200+).
no manufacturer or retailer i know of tells you any more specifics, such as
timings so ignore the rest.
As to amount of RAM....errr i'm going to say this later but any 32 bit OS is
limited to 4GB of memory (excluding PAE but that isent relevant as 4 GB
'aint the major barrier.
On windows memory is handled pretty awfully. what happen when you have4 gigs
of memory is say for example on 32bit XP, each process is essentially
limited to 1.8 gb.
Last point, don't run dynamips on windows. Its running not quite natively on
an architecture which bears little resemblence to the robust unix box it was
designed for, which
happens to have awful memory management, a bolted on network stack, pitiful
management of multiple processors and multithreading that grinds to a halt
when under load.
thats not microsoft-bashing, windows is severely structurally flawed due to
the bolting on of not just features but entire concepts (like multi-user and
networking), both apply to dynamips.
Linux will run daynamips with the same configs 10-20% faster on any
processor. and it won't become unusable at 100% cpu usage because processes
are pretty much forced to play nice.
If you are voluntarily using dynamips on vista i'd call the nice doctors in
the white coats or you could get a job far enough away from computers that
you cant hurt them anymore.
Do use any 64bit distro of linux, do download the source code from the
dynamips site, do compile using gcc 3.2+ using cpu specific optimisation and
the -O3 option for threading, do set your idle-pc correctly.]
I emulate up to 24 7200s simultaneously here on my laptop (2.33Ghz Core 2,
4GB Ram).
Apologies for the quasi-religous ferver.
Regards,
Noel Bourke
On 6/9/07, Con Spathas <con@spathas.net> wrote:
>
> Check out http://7200emu.hacki.at/
>
> This question has been asked many times there!
>
> Cheers...
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> lalit gupta
> Sent: Saturday, 9 June 2007 08:19
> To: Cisco certification
> Subject: Maximum number of instances on dynamips/dynagen.u
> I am planning to buy a laptop for running maximum number of instances on
> dynamips/dynagen.
>
> Which configuration will you geniuses recommend.
>
> 1) AMD 64-bit process 2GHz
> 2 GB RAM
> or
> 2) Core 2 Duo processor 2 GHz
> 2 GB RAM
>
> Also will it help if I increase the RAM further more.
>
> Please if you can given any more information which will be useful please
> don't hesitate to reply.....
>
> Regards
> lalit
>
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