Hello All,
I received clarification from qa.gem5.org(
http://qa.gem5.org/132/timing-cpu-model) on this issue.
"The TimingSimpleCPU is a 1 CPI CPU model that uses a timing back-end for
memory latencies, so it's not surprising that you'd see little change in a
cpu-bound benchmark when varying the clock. Try running a memory intensive
benchmark, such as mcf from SPEC, and you should see a difference. If you
need detailed timing information out of the CPU, use the O3 model." - Tony
Regarding the other questions that I have not responded to,
@Tao Zhang,
I just never enabled --caches as Gem5 did not complain about it (Gem5 does
complain about it when trying to use o3 model without caches).
I was a little doubtful about --cpu-type=detailed..I had questioned this
earlier as well..My CPU bound benchmark works as intended while using
arm_detailed with --caches.
@Rehab Massoud,
The time does make sense, yes. But the last number computed should be
proportional to the CPU frequency..the higher the frequency, the more
computations per unit time. However, the timing model was not reflecting
this..hence my post.
@Andrws Vieira,
The variable 'Number' is the last number that it tried to test (whether it
was prime or not).
My primality test function is as follows,
typedef unsigned long long ull;
static inline int is_prime(int number) {
ull divisor = 3;
if(number == 1ULL ) {
//1 is neither prime nor composite
return 0;
}
if(number % 2 == 0) {
return 0; //even no.
}
// Every prime number is of the form 6n (+|-) 1
if(number % 6 != 1 || number % 6 != 5) {
return 1;
}
while ( divisor <= (number / 2) ) {
if (number % divisor == 0) {
return 0;
}
divisor += 2;
}
return 1;
}
Below is the pseudo code of my main function
main(argc, argv) {
...
start_time = get_current_time()
ull number = 1;
while(1) {
is_prime(number);
if( (get_current_time() - start_time) >= end_time //end_time part
of argv
break;
number++;
}
}
Thank you for your insights into this issue..
Regards
Guru
On Fri, May 31, 2013 at 6:27 AM, Andrws Vieira <andrwsvie...@gmail.com>wrote:
> Hello Guru,
>
> What is the variable "Nunber" ?
>
>
> []'s
>
>
> 2013/5/31 Rehab Massoud <rehab.mass...@gmail.com>
>
>> Didn't you say that you're running a program that's given a timeout? The
>> timeout you specify is expected to be the time you got, so your results
>> make all the sense, isn't it?
>> On May 31, 2013 8:24 AM, "Guru Prasad" <gurup...@buffalo.edu> wrote:
>>
>>> Hi Andrws,
>>> This is the output i obtained running with the configuration mentioned.
>>>
>>> 01 GHz
>>> Time taken :0.1000000s
>>> Number :189055
>>>
>>>
>>> 04 GHz
>>> Time taken :0.1000000s
>>> Number :392151
>>>
>>>
>>> 10 GHz
>>> Time taken :0.1000000s
>>> Number :472726
>>>
>>> It does seem to correlate with what I would expect to be the output with
>>> change in frequency.
>>>
>>> I will need to test further (or read appropriate documentation) to
>>> ensure that timing model is actually being used in the command line
>>> mentioned above.
>>>
>>> Thank you for your suggestions.
>>>
>>> Regards
>>> Guru
>>>
>>>
>>>
>>> On Thu, May 30, 2013 at 2:55 PM, Guru Prasad <gurup...@buffalo.edu>wrote:
>>>
>>>> Hi Andrws,
>>>>
>>>> I'm running the simulations right now..
>>>> Could I ask how this makes a difference?
>>>>
>>>> Also, (How) is this different from --cpu-type=arm_detailed?
>>>>
>>>> This will be my command line..do let me know if there is an issue with
>>>> it
>>>> build/ARM/gem5.fast configs/example/fs.py --kernel
>>>> /home/guru/gem5/kernel/linux-3.3-armdroid/vmlinux --disk-image
>>>> /home/guru/gem5/gem5-stable/system/disks/android_jb_pa_spec.img
>>>> --machine-type=VExpress_EMM --clock=1GHz --cpu-type=timing --num-cpus=1
>>>> --caches --cpu-type=detailed
>>>>
>>>>
>>>>
>>>> R
>>>> egards
>>>>
>>>> Guru
>>>>
>>>>
>>>>
>>>> On Thu, May 30, 2013 at 2:36 PM, Andrws Vieira
>>>> <andrwsvie...@gmail.com>wrote:
>>>>
>>>>> Hi Guru,
>>>>>
>>>>> Try to put in the end of command line: *cpu-type=detailed*
>>>>> *
>>>>> *
>>>>> Like this -> build/ARM/gem5.fast configs/example/fs.py --kernel
>>>>> /home/guru/gem5/kernel/linux-3.3-armdroid/vmlinux --disk-image
>>>>> /home/guru/gem5/gem5-stable/system/disks/android_jb_pa_spec.img
>>>>> --machine-type=VExpress_EMM --clock=4GHz --cpu-type=timing --num-cpus=1 --
>>>>> *cpu-type=detailed*
>>>>> *
>>>>> *
>>>>> *
>>>>> *
>>>>> []'s
>>>>>
>>>>>
>>>>> 2013/5/30 Guru Prasad <gurup...@buffalo.edu>
>>>>>
>>>>>> Here are some results
>>>>>>
>>>>>> Atomic
>>>>>> 01 GHz
>>>>>> Time taken :0.1000006s
>>>>>> Number :142617
>>>>>>
>>>>>> 04 GHz
>>>>>> Time taken :0.1000003s
>>>>>> Number :575327
>>>>>>
>>>>>> 10 GHz
>>>>>> Time taken :0.1000003s
>>>>>> Number :1428815
>>>>>>
>>>>>>
>>>>>>
>>>>>> Timing
>>>>>> 01 GHz
>>>>>> Time taken :0.1000310s
>>>>>> Number :4597
>>>>>>
>>>>>> 04 GHz
>>>>>> Time taken :0.1000302s
>>>>>> Number :4657
>>>>>>
>>>>>> 10 GHz
>>>>>> Time taken :0.1000297s
>>>>>> Number :4643
>>>>>>
>>>>>>
>>>>>> Maybe this is how timing is supposed to work..I'm not sure..
>>>>>> I just didn't understand it and wanted to ask other users
>>>>>>
>>>>>> Regards
>>>>>> Guru
>>>>>>
>>>>>>
>>>>>>
>>>>>> On Thu, May 30, 2013 at 2:09 PM, Guru Prasad <gurup...@buffalo.edu>wrote:
>>>>>>
>>>>>>> Hi Andreas,
>>>>>>>
>>>>>>> The output of my program is the same.
>>>>>>> I'm running primality test program that is given a time bound.
>>>>>>>
>>>>>>> I
>>>>>>> t returns the last number that it tested when it runs out of time.
>>>>>>>
>>>>>>> I would expect the last number computed to differ based on frequency
>>>>>>> specified while running Gem5.
>>>>>>>
>>>>>>> This differs significantly when using both, Atomic model and O3..
>>>>>>> But regardless of the --clock parameter, timing model always gives
>>>>>>> me results that are very close.
>>>>>>>
>>>>>>>
>>>>>>> My command line parameters are
>>>>>>>
>>>>>>> build/ARM/gem5.fast configs/example/fs.py --kernel
>>>>>>> /home/guru/gem5/kernel/linux-3.3-armdroid/vmlinux --disk-image
>>>>>>> /home/guru/gem5/gem5-stable/system/disks/android_jb_pa_spec.img
>>>>>>> --machine-type=VExpress_EMM --clock=4GHz --cpu-type=timing --num-cpus=1
>>>>>>>
>>>>>>> I am working with a slightly outdated gem5 source..I believe my
>>>>>>> revision is 9197
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> On Thu, May 30, 2013 at 1:57 PM, Andreas Hansson <
>>>>>>> andreas.hans...@arm.com> wrote:
>>>>>>>
>>>>>>>> Hi Guru,
>>>>>>>>
>>>>>>>> Could you perhaps elaborate on "same results"? Are all stats
>>>>>>>> exactly the same, or is the output of the program the same? Also, what
>>>>>>>> config script are you running?
>>>>>>>>
>>>>>>>> Andreas
>>>>>>>>
>>>>>>>> From: Guru Prasad <gurup...@buffalo.edu>
>>>>>>>> Reply-To: gem5 users mailing list <gem5-users@gem5.org>
>>>>>>>> Date: Thursday, 30 May 2013 18:45
>>>>>>>> To: "gem5-users@gem5.org" <gem5-users@gem5.org>, "gem5-...@gem5.org"
>>>>>>>> <gem5-...@gem5.org>
>>>>>>>> Subject: [gem5-users] Timing CPU model
>>>>>>>>
>>>>>>>> I was recently running some tests using the timing CPU model and
>>>>>>>> noticed that my cpu-bound workload was always producing the same
>>>>>>>> results
>>>>>>>> regardless of the --clock parameter specified.
>>>>>>>>
>>>>>>>> I tested this with
>>>>>>>> --clock=0.1GHz (not sure if floating points work for parameters)
>>>>>>>> --clock=1GHz
>>>>>>>> --clock=4GHz
>>>>>>>> --clock=10GHz
>>>>>>>>
>>>>>>>> Could anyone explain to me why this is the case? Is there something
>>>>>>>> implicit in the timing model that I'm not quite grasping?
>>>>>>>>
>>>>>>>> -- IMPORTANT NOTICE: The contents of this email and any attachments
>>>>>>>> are confidential and may also be privileged. If you are not the
>>>>>>>> intended
>>>>>>>> recipient, please notify the sender immediately and do not disclose the
>>>>>>>> contents to any other person, use it for any purpose, or store or copy
>>>>>>>> the
>>>>>>>> information in any medium. Thank you.
>>>>>>>>
>>>>>>>> _______________________________________________
>>>>>>>> gem5-users mailing list
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>>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>
>>>>>> _______________________________________________
>>>>>> gem5-users mailing list
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>>>>>>
>>>>>
>>>>>
>>>>>
>>>>> --
>>>>> *Andrws Aires Vieira *
>>>>> Mestrando em Computação
>>>>> Universidade Federal do Rio Grande do Sul - UFRGS
>>>>>
>>>>> _______________________________________________
>>>>> gem5-users mailing list
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>>>>>
>>>>
>>>>
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>
>
>
> --
> *Andrws Aires Vieira *
> Mestrando em Computação
> Universidade Federal do Rio Grande do Sul - UFRGS
>
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> gem5-users mailing list
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