Re: Building a computer for compiling and CPU emulation (Re: Building computer)
On 10/1/2013 9:16 AM, Joel Rees wrote:
> On Tue, Oct 1, 2013 at 7:00 AM, Stan Hoeppner <stan@hardwarefreak.com> wrote:
>> On 9/29/2013 6:01 AM, Joel Rees wrote:
>> ...
>>> http://en.wikipedia.org/wiki/List_of_AMD_mobile_microprocessors
>>>
>>> tells me that AMD A4-1250, AMD A6-1450, and E2-1800 all have AMD-V.
>>>
>>> The E2-1800 has a half-Meg L2 cache, but higher speed CPU (1.7GHz).
>>>
>>> The A4-1250 has 1 Meg L2 cache but lower speed CPU (1.0 GHz).
>>>
>>> The A6-1450 has 2 Meg L2 cache to share between twice the CPUs.
>>
>> The A4-1450 is probably the best choice, not taking cost into
>> consideration. Here's why:
>>
>> 1. Turbo core up to 1.4GHz
>>
>> 2. All 3 models have 512KB L2/core, no advantage for any
>>
>> 3. Temash core has better IPC than Zacate
>>
>> 4. 4 cores @ 1.4GHz should give better compile times than
>> 2 cores @ 1.8GHz. 4 @ 1GHz should as well. -j4 or higher
>>
>> 5. A6-1450 is 9W chip, E2-1800 is 18W chip, longer run time
>> 28nm vs 40nm
>>
>> The one downside is that for non-compute intensive operations, such as
>> normal interactive GUI apps, say PDF viewing, browser rendering, etc, it
>> may be considerably slower than the 1.8GHz E2-1800, due to the 800MHz
>> clock deficit, as the turbo core may not kick in a lot here. And WRT
>> turbo core, I'm not quite sure what this means:
>>
>> "Selected parts support Turbo Dock technology, that can increase CPU and
>> GPU frequencies when external cooling is available."
>>
>> So if the unit you purchase doesn't have a variable speed fan that can
>> fulfill this requirement, this may mean you can't get 1.4GHz turbo mode.
>> And I'm just guessing that devices of this class may not include forced
>> air cooling. Sorry I don't have all the answers here, but maybe this
>> helps get you a bit closer.
>>
>> One thing I can assure you of is that for your stated use case, IIUI
>> correctly, all of these CPUs are very likely woefully inadequate for the
>> task.
>
> Yes and no. Most of the compiling will be much smaller than a kernel,
> not even complete packages. I think I said it but you've clipped that
> part, but this is a course in programming that includes writing some
> drivers.
Got it. Yeah, compiling a few hundred or thousand lines of code
shouldn't be that bad.
> Emulating the superH processor is going to be a bit demanding,
Instruction set level emulation is going to be extremely demanding if
you intend to run a complete emulated OS environment. If you strictly
use it for things like executing and debugging individual subroutines,
code segments, etc, it shouldn't be too bad.
> particularly if I find myself wanting to compile a superH kernel and
> not having access to the school labs over a long holiday. I am aware
> of that and will plan accordingly.
Yep.
> Mostly, I was trying to dig up the AMD-V support and something in the
> thread pointed me the right direction.
Having AMD-V or Intel VT isn't an absolute requirement. Both will speed
up context switches. As important as the new thread switching hardware
in these CPUs is the size of the TLBs. CPUs without virtualization
support tend to have inadequate TLBs. When you switch between VMs you
end up flushing most of the TLB entries and reloading them.
CPUs with large L2/L3 caches help mitigate this to a degree. Which is
one of the reasons you see ginormous caches on server oriented CPUs,
Xeon and Opteron, up to 34MB combined L2/L3. Most server workloads are
transaction oriented and throughput is dictated by network/disk latency.
A huge cache does nothing for you here. But when you run many virtual
machines it provides serious benefit.
This is one of the reasons I recommended going for the largest cache you
can get. Unfortunately there's not much difference in cache sizes in
the processor class you're looking at.
Have you considered a refurb or used laptop? The Core2 Duo SL9600
offers 2.13GHz clock, 6MB L2 cache, at 17W. The Mobile PhenomII P650
2.6GHz clock w/2MB L2, 25W.
> I'm not planning getting more than AMD-V in a portable machine. Don't
> want to carry a boat battery with me. :-p
Heheh, love the deep cycle reference. Though if you're like many mobile
users, in the States anyway, most of the time a wall plug isn't far
away, in either distance or time. Never visited Japan so I can comment
on the situation there.
--
Stan
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