Thanks a lot for clarification.
I didn't know about that.
ᐧ

On Mon, Aug 3, 2015 at 9:47 AM, Guru Prasad <[email protected]> wrote:

> Gem5 has a command line argument --dual. This starts up 2 separate
> simulations (inside 1 process) where one is called the driver and the other
> is the 'real' test system.
> Since networking requires at least two systems, you usually use --dual
> when you want to test the network. Because gem5 is not yet multi-threaded
> (I think), both simulations end up using only 1 core.
> Hence, ideally this should result in a 2x slowdown. However, I'm seeing a
> lot more. That's what my question was about.
>
> My single system simulations also take about 12-15 hours to complete. With
> detailed they take a lot longer (haven't fully completed a sim yet).
>
> Regards
> Guru
>
>
>
> On Mon, Aug 3, 2015 at 12:42 PM, Davesh Shingari <[email protected]
> > wrote:
>
>> Just to be sure,what do you mean by dual?
>> Do you mean 2 simulation or multiple core configuration?
>> ᐧ
>>
>> On Mon, Aug 3, 2015 at 9:39 AM, Guru Prasad <[email protected]> wrote:
>>
>>> Hi Davesh, just to clarify, is this with --dual?
>>>
>>> Regards
>>> Guru
>>>
>>>
>>> On Mon, Aug 3, 2015 at 12:38 PM, Davesh Shingari <
>>> [email protected]> wrote:
>>>
>>>> Hi Guru
>>>>
>>>> I am using Android on Gem5 for my work. When I use the simulation to
>>>> take checkpoint, then it takes around 12 - 15 hours to get checkpoint and
>>>> finish simulation. The simulation time is 32 seconds after the checkpoint.
>>>> But when I use that checkpoint along with detailed mode configuration and
>>>> full memory system, then it takes almost a week to complete.
>>>> ᐧ
>>>>
>>>> On Mon, Aug 3, 2015 at 9:23 AM, Guru Prasad <[email protected]>
>>>> wrote:
>>>>
>>>>> Ah I see. It sounds like the sort of like the hack we made for hdlcd
>>>>> where we read from physical memory directly.
>>>>>
>>>>> Thanks once again. I will try the options you've described.
>>>>>
>>>>> Regards
>>>>> Guru
>>>>>
>>>>>
>>>>> On Mon, Aug 3, 2015 at 12:19 PM, Andreas Hansson
>>>>> <[email protected]> wrote:
>>>>> > Hi Guru,
>>>>> >
>>>>> > 3 days for 20 seconds sounds way slower than it should be.
>>>>> >
>>>>> > Fast-mem is not replacing the DRAM controller, it bypasses the entire
>>>>> > memory system. In atomic we do not do any sensible timing simulation
>>>>> of
>>>>> > the controller in any case.
>>>>> >
>>>>> > The KVM CPU is only built if your system support it. Hence, you need
>>>>> to
>>>>> > build gem5 for ARM on an ARM system. A good reason to get an ARM
>>>>> server :-)
>>>>> >
>>>>> > Andreas
>>>>> >
>>>>> > On 03/08/2015 16:46, "gem5-users on behalf of Guru Prasad"
>>>>> > <[email protected] on behalf of [email protected]>
>>>>> wrote:
>>>>> >
>>>>> >>Hi Andreas,
>>>>> >>
>>>>> >>Thanks for the suggestions. It took about 3 days to simulate
>>>>> 20seconds
>>>>> >>under atomic.
>>>>> >>I don't know how to tell if interrupts are being lost. The kernel is
>>>>> >>not complaining about anything on kmsg.
>>>>> >>I will try atomic with --fast-mem. Currently, I've been using
>>>>> >>lpddr3_1600_x32
>>>>> >>
>>>>> >>I don't think I have KvmArmCPU available. I will try the same with
>>>>> the
>>>>> >>latest.
>>>>> >>Is using KvmArmCPU as simple as just saying --cpu-type=...?
>>>>> >>I ask this because --list-cpu-types for my current version only
>>>>> displays
>>>>> >>    timing => TimingSimpleCPU
>>>>> >>    detailed => DerivO3CPU
>>>>> >>    atomic => AtomicSimpleCPU
>>>>> >>    minor => MinorCPU
>>>>> >>
>>>>> >>
>>>>> >>Regards
>>>>> >>Guru
>>>>> >>
>>>>> >>On Mon, Aug 3, 2015 at 11:33 AM, Andreas Hansson
>>>>> >><[email protected]> wrote:
>>>>> >>> Hi Guru,
>>>>> >>>
>>>>> >>> To speed things up, here are some options:
>>>>> >>>
>>>>> >>> 1. Use atomic to get the point of interest, then take a
>>>>> checkpoint. Is
>>>>> >>> this what you are doing?
>>>>> >>>
>>>>> >>> 2. For the above, run with --fast-mem since you’re not warming any
>>>>> >>>caches
>>>>> >>> anyways.
>>>>> >>>
>>>>> >>> 3. If possible, use the KvmArmCPU instead of (1). This should give
>>>>> you a
>>>>> >>> significant boost.
>>>>> >>>
>>>>> >>> If the amount of work is constant, than running with dual should
>>>>> not
>>>>> >>>slow
>>>>> >>> things down. If you’re seeing a slow down, then perhaps something
>>>>> odd is
>>>>> >>> going on in the simulation (interrupts getting lost etc). Have you
>>>>> tried
>>>>> >>> with the latest trunk?
>>>>> >>>
>>>>> >>> Andreas
>>>>> >>>
>>>>> >>>
>>>>> >>> On 03/08/2015 16:16, "gem5-users on behalf of Guru Prasad"
>>>>> >>> <[email protected] on behalf of [email protected]>
>>>>> wrote:
>>>>> >>>
>>>>> >>>>Hi,
>>>>> >>>>
>>>>> >>>>Recently we've been trying to run some experiments with the
>>>>> network.
>>>>> >>>>To do so, we've been using dual simulations. So far, we've been
>>>>> able
>>>>> >>>>to get away with running two simulations booting barebones linux
>>>>> with
>>>>> >>>>just a shell. However, our real workload is BBench and so we need
>>>>> to
>>>>> >>>>boot a full Android image.
>>>>> >>>>
>>>>> >>>>A single simulation of full Android takes us about ~12hours to
>>>>> boot.
>>>>> >>>>However under dual, its been about 3 days and has so far simulated
>>>>> >>>>only ~20seconds. Is there any way to speed up the simulation? Is
>>>>> there
>>>>> >>>>any way we can stitch two single simulations together (initial
>>>>> loss of
>>>>> >>>>time on drivesys is acceptable).
>>>>> >>>>
>>>>> >>>>Currently we're on revision e179497451.
>>>>> >>>>
>>>>> >>>>Regards
>>>>> >>>>Guru
>>>>> >>>>_______________________________________________
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>>>>
>>>>
>>>>
>>>> --
>>>> Have a great day!
>>>>
>>>> Thanks and Warm Regards
>>>> Davesh Shingari
>>>> Master's in Computer Engineering [EE]
>>>> Arizona State University
>>>>
>>>> [email protected]
>>>>
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>>
>>
>> --
>> Have a great day!
>>
>> Thanks and Warm Regards
>> Davesh Shingari
>> Master's in Computer Engineering [EE]
>> Arizona State University
>>
>> [email protected]
>>
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-- 
Have a great day!

Thanks and Warm Regards
Davesh Shingari
Master's in Computer Engineering [EE]
Arizona State University

[email protected]
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