Hello, I didn't follow the whole discussion, but I have a point, regarding the Timing model:
1) If you run with caches, usually what happens when running linux, your cpu isn't limited by the slow main memory, so your bogomips may change with the cpu frequency. 2) If you run without caches and with relative high clock speeds, your cpu will be mainly limited by the slow main memory, so the latter will basically define your apparent constant bogomips ~33. If you try to without caches and a very slow cpu freq, I'd say your bogomips could be less than ~33. Hope it helps, Fernando -- Fernando A. Endo, PhD student and researcher Université de Grenoble, UJF France 2013/6/6 Guru Prasad <gurup...@buffalo.edu> > Please disregard the previous E-mail. > It has some wrong facts > > > Hi All, > > A small follow-up on this question. > > TimingSimpleCPU model seems to work more consistently with --caches > enabled. However, the Linux kernel is still unable to accurately compute > loops per jiffy for the timing model CPU..(it always computes 997 BogoMIPS) > > My program output also seems to suggest that regardless of the --clock > frequency specified, the output is always the same and it is close to the > values obtained from AtomicSimpleCPU model running at 1GHz. > > AtomicSimpleCPU > build/ARM/gem5.fast configs/example/fs.py -b cpufreq_test --kernel > /home/guru/gem5/kernel/linux-3.3-armdroid/vmlinux --disk-image > /home/guru/gem5/gem5-dev/system/disks/android_jb_pa_final.img > --machine-type=VExpress_EMM --clock=1GHz --cpu-type=atomic --num-cpus=1 > > [ 1.769154] Time taken :0.0100000s > [ 1.769157] Number :14249 > > > TimingSimpleCPU (with --caches) > build/ARM/gem5.fast configs/example/fs.py -b cpufreq_test --kernel > /home/guru/gem5/kernel/linux-3.3-armdroid/vmlinux --disk-image > /home/guru/gem5/gem5-dev/system/disks/android_jb_pa_final.img > --machine-type=VExpress_EMM --clock=1GHz --cpu-type=timing --caches > --num-cpus=1 > > [ 1.925451] Time taken :0.0100010s > [ 1.925457] Number :12300 > > > I have also noticed that without --caches, the kernel always computes > 32.97 BogoMIPS regardless of the --clock argument specified.. > > TimingSimpleCPU (without --caches) > build/ARM/gem5.fast configs/example/fs.py -b cpufreq_test --kernel > /home/guru/gem5/kernel/linux-3.3-armdroid/vmlinux --disk-image > /home/guru/gem5/gem5-dev/system/disks/android_jb_pa_final.img > --machine-type=VExpress_EMM --clock=1GHz --cpu-type=timing --num-cpus=1 > > [ 5.286962] Time taken :0.0100310s > [ 5.287082] Number :454 > > > In both TimingSimpleCPU configurations, regardless of the --clock > parameter specified, the output does not vary much from the specified > values. > > I'm still not sure as to why this is happening.. > > Any thoughts? > > > Regards > > > On Thu, Jun 6, 2013 at 11:01 AM, Guru Prasad <gurup...@buffalo.edu> wrote: > >> Hi All, >> >> A small follow-up on this question. >> >> @Tao Zhang was actually right. >> Timing CPU works as 'expected' when I enable caches with it. >> >> Why I say 'expected' is because, the Linux kernel is still unable to >> accurately compute loops per jiffy for the timing model CPU..(it always >> computes 997 BogoMIPS) >> However, the output seems to now correlate with changes in --clock values >> (I don't know if its correct though..what I mean is - higher clock seems to >> correspond to more operations executed). >> >> I have also noticed that without --caches, the kernel always computes >> 32.7 BogoMIPS regardless of the --clock argument specified.. >> I'm still not sure as to why this is happening.. >> >> Any thoughts? >> >> >> Regards >> Guru >> >> >> >> On Mon, Jun 3, 2013 at 10:31 AM, Guru Prasad <gurup...@buffalo.edu>wrote: >> >>> 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 >>>>>>>>>>> gem5-users@gem5.org >>>>>>>>>>> http://m5sim.org/cgi-bin/mailman/listinfo/gem5-users >>>>>>>>>>> >>>>>>>>>> >>>>>>>>>> >>>>>>>>> >>>>>>>>> _______________________________________________ >>>>>>>>> gem5-users mailing list >>>>>>>>> gem5-users@gem5.org >>>>>>>>> http://m5sim.org/cgi-bin/mailman/listinfo/gem5-users >>>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> -- >>>>>>>> *Andrws Aires Vieira * >>>>>>>> Mestrando em Computação >>>>>>>> Universidade Federal do Rio Grande do Sul - UFRGS >>>>>>>> >>>>>>>> _______________________________________________ >>>>>>>> gem5-users mailing list >>>>>>>> gem5-users@gem5.org >>>>>>>> http://m5sim.org/cgi-bin/mailman/listinfo/gem5-users >>>>>>>> >>>>>>> >>>>>>> >>>>>> >>>>>> _______________________________________________ >>>>>> gem5-users mailing list >>>>>> gem5-users@gem5.org >>>>>> http://m5sim.org/cgi-bin/mailman/listinfo/gem5-users >>>>>> >>>>> >>>>> _______________________________________________ >>>>> gem5-users mailing list >>>>> gem5-users@gem5.org >>>>> http://m5sim.org/cgi-bin/mailman/listinfo/gem5-users >>>>> >>>> >>>> >>>> >>>> -- >>>> *Andrws Aires Vieira * >>>> Mestrando em Computação >>>> Universidade Federal do Rio Grande do Sul - UFRGS >>>> >>>> _______________________________________________ >>>> gem5-users mailing list >>>> gem5-users@gem5.org >>>> http://m5sim.org/cgi-bin/mailman/listinfo/gem5-users >>>> >>> >>> >> > > _______________________________________________ > gem5-users mailing list > gem5-users@gem5.org > http://m5sim.org/cgi-bin/mailman/listinfo/gem5-users >
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