Re: [gem5-users] Using Simpoints in gem5

[Ciro Santilli]

Hi Pawan, isn't it the situation here the same for checkpoints and
simpoints? https://www.mail-archive.com/gem5-users@gem5.org/msg15457.html

On Wed, May 9, 2018 at 4:24 AM, Pawan Joshi  wrote:
> Hello
> Is it not possible to use the checkpoints generated using an Atomic simple
> CPU to restore them on a DerivO3CPU?
> Also, what do the -cpu-type and -restore-from-cpu mean in restoring from
> checkpoints? The new stats I manually added do not appear in the switch_cpus
> when I do -restore-from-cpu = DerivO3CPU? They only appear in the
> system.cpu, where most of the stats (including committed insts, etc) are all
> zero.
>
>
>
> Thanks
> Pawan B Joshi
> Electrical and Computer Engineering
> The University of Texas-Austin
>
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[gem5-users] Using Simpoints in gem5

[Pawan Joshi]

Hello
Is it not possible to use the checkpoints generated using an Atomic simple
CPU to restore them on a DerivO3CPU?
Also, what do the -cpu-type and -restore-from-cpu mean in restoring from
checkpoints? The new stats I manually added do not appear in the
switch_cpus when I do -restore-from-cpu = DerivO3CPU? They only appear in
the system.cpu, where most of the stats (including committed insts, etc)
are all zero.



Thanks
Pawan B Joshi
Electrical and Computer Engineering
The University of Texas-Austin
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Re: [gem5-users] Using Simpoints in gem5

[Ciro Santilli]

Hi Pawan,

Remember to always reply to both me and the gem5-users list to share
the knowledge, I only noticed this on you latest message. Proposal for
a more modern issue tracker at:
https://www.mail-archive.com/gem5-dev@gem5.org/msg24951.html

> AttributeError: object 'System' has no attribute 'switch_cpus'

This is exactly what is mentioned on the link I sent on my previous
message :-) 
https://stackoverflow.com/questions/49011096/how-to-switch-cpu-models-in-gem5-after-restoring-a-checkpoint-and-then-observe-t/49673265#49673265

> Except confuse me, since if --cpu-type != --restore-with-cpu, then the cycle 
> count appears under system.switch_cpus.numCycles instead of 
> system.cpu.numCycles.

I am not 100% sure since I'm new, but I think this is the rationale
behind this weird interface (not fully tested):

- switch_cpu contains stats for the CPU you switched to
- when you set cpu_type != switch_cpu, it thinks you have already
switched CPUs from the start
- --restore-with-cpu= has no effect on the initial CPU, it only
matters for options that switch the CPU during the run itself, e.g.
--fast-forward and --repeat_switch

On Mon, May 7, 2018 at 11:43 PM, Pawan Joshi  wrote:
> Also, when I run with --cpu-type = DerivO3CPU and
> --restore-with-cpu=DerivO3CPU, I get the error:
>
> File
> "/home/pawan/Desktop/Pred_mech/Project/VTAGE-gem5/src/python/m5/SimObject.py",
> line 1130, in __getattr__
> AttributeError: object 'System' has no attribute 'switch_cpus'
>   (C++ object is not yet constructed, so wrapped C++ methods are
> unavailable.)
>
> Hope that can help you find a solution.
>
> Pawan
>
>
> Pawan B Joshi
> Electrical and Computer Engineering
> The University of Texas-Austin
>
> On Sun, May 6, 2018 at 4:44 PM, Pawan Joshi  wrote:
>>
>> I am not seeing the stats I put for value prediction appear correctly - it
>> says there are zero values eligible during the region of interest (250M).
>> Is it because I checkpointed Atomic CPU and now am using  DerivO3CPU along
>> with added value prediction features?
>
>
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Re: [gem5-users] Using Simpoints in gem5

[Ciro Santilli]

What do you mean by poor results?

My experiments with changes of cache size and CPU type gave results
which seem consistent:

- 
https://github.com/cirosantilli/linux-kernel-module-cheat/blob/237b7603b7972142a99aab1a609aef12522d0ef7/gem5-bench-cache#L39
- 
https://stackoverflow.com/questions/49011096/how-to-switch-cpu-models-in-gem5-after-restoring-a-checkpoint-and-then-observe-t/49673265#49673265

On Sun, May 6, 2018 at 7:17 PM, Pawan Joshi  wrote:
> Hello
> Does the system config (CPU, caches, etc) used while taking checkpoints need
> to be the same as the one used while restoring from checkpoints? I used
> AtomicSimpleCPU while taking checkpoints, but I seem to see very poor
> results when I use a different CPU while restoring.
>
> Thanks
> Pawan B Joshi
> Electrical and Computer Engineering
> The University of Texas-Austin
>
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[gem5-users] Using Simpoints in gem5

[Pawan Joshi]

Hello
Does the system config (CPU, caches, etc) used while taking checkpoints
need to be the same as the one used while restoring from checkpoints? I
used AtomicSimpleCPU while taking checkpoints, but I seem to see very poor
results when I use a different CPU while restoring.

Thanks
Pawan B Joshi
Electrical and Computer Engineering
The University of Texas-Austin
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