Why not? HEAD_TAIL_ is equivalent to a HEAD_ right (it just so happens that there are no BODY and TAIL flits in this packet). It still needs to choose a route, reserve a VC (a 1-flit-deep VC in this case).
- Tushar On Oct 1, 2012, at 1:58 PM, Pavan Poluri wrote: > Hello, > > Thanks for your reply. If the 1-flit packets of type HEAD_TAIL_ are control > messages, I am unable to figure out why do we need to perform Routing > Computation, Virtual Channel allocation etc computations on these HEAD_TAIL_ > flits? > > Thanks for your time. > > Thanks, > Pavan > > On Tue, Sep 25, 2012 at 9:53 PM, Tushar Krishna <tus...@csail.mit.edu> wrote: > Yes 1-flit packets (of type HEAD_TAIL_) are control messages from the > protocol. > > - Tushar > > On Sep 25, 2012, at 8:04 PM, Pavan Poluri wrote: > >> Hello, >> >> I have a question on the single flit packets generated when synthetic >> traffic simulation is used. These 1 flit packets are of type HEAD_TAIL_. >> According to the default settings, control message (8 bytes) occupies 1 flit >> and a data message (72 bytes) occupies 5 flits, where each flit is 16 bytes. >> My question is, >> >> Are these 1 flit packets of type HEAD_TAIL_ control messages or are they >> something different? >> >> Thanks for your time. >> >> Thanks, >> Pavan >> >> On Mon, Sep 17, 2012 at 1:56 PM, Pavan Poluri <poluripa...@gmail.com> wrote: >> Thanks Tushar. >> >> Thanks, >> Pavan >> >> >> On Mon, Sep 17, 2012 at 11:49 AM, Tushar Krishna <tus...@csail.mit.edu> >> wrote: >> Yes all that is correct. >> >> data msg size is 72 bytes, not 80. I will correct that on the wiki. >> >> cheers, >> Tushar >> >> >> On Sep 17, 2012, at 2:05 PM, Pavan Poluri wrote: >> >>> Thank you. I just to make sure that I understood it the right way. >>> >>> In the file network/Network.py, in the declaration of RubyNetwork class >>> control message size is defined as >>> >>> control_msg_size = Param.Int(8, ""); >>> >>> So the control message size (m_control_msg_size) is 8 bytes. >>> >>> According to network/Network.cc, the data message size (m_data_msg_size) is >>> >>> m_data_msg_size = RubySystem::getBlockSizeBytes() + m_control_msg_size >>> >>> From ruby/system/RubySystem.py, >>> >>> block_size_bytes = Param.Int(64, "default cache block size") >>> >>> Therefore, m_data_size = 64+8 = 72 bytes. >>> >>> Since the flit size is 16 bytes, an 8 byte control message takes 1 flit and >>> 72 bytes data message takes 5 flits. >>> >>> Am I correct? >>> >>> Thanks, >>> Pavan >>> >>> On Mon, Sep 17, 2012 at 10:04 AM, Tushar Krishna <tus...@csail.mit.edu> >>> wrote: >>> Answers inline. >>> >>> On Sep 17, 2012, at 12:42 PM, Pavan Poluri wrote: >>> >>>> Hello, >>>> >>>> I have a question on the ni_flit_size parameter in the file >>>> garnet/BaseGarnetNetwork.py. From the documentation I understood that >>>> ni_flit_size specifies the flit size in bytes. The default value is 16 >>>> bytes. In the documentation, it says that this results in a control >>>> message fitting in 1 flit and data message fitting in 5 flits. So this >>>> means that the control message is 16 bytes and the data message is 80 >>>> bytes. The following are the two questions I have: >>>> >>>> 1. Lets say if I change the ni_flit_size to 8 bytes, would it >>>> automatically translate to a control message that fits in 2 flits and data >>>> message fitting in 10 flits? >>>> >>> Yes. Take a look at NetworkInterface_d.cc where number of flits are >>> calculated. >>> >>>> 2. Are the sizes of control message (16 bytes) and data message (80 bytes) >>>> fixed? Is it possible to modify their sizes? >>>> >>> Take a look at network/Network.py/cc >>> >>>> Thanks for your time. >>>> >>>> Thanks, >>>> Pavan >>>> >>>> On Wed, Sep 12, 2012 at 2:54 PM, Pavan Poluri <poluripa...@gmail.com> >>>> wrote: >>>> Thanks Tushar. >>>> >>>> Thanks, >>>> Pavan >>>> >>>> >>>> On Wed, Sep 12, 2012 at 12:23 PM, Tushar Krishna <tus...@csail.mit.edu> >>>> wrote: >>>> If you divide the total flits by total cycles by 16, you can see that the >>>> injection rate is only 0.0009 flits/cycle/node. Hence your power is so low. >>>> The total network energy might be an alternate metric that you might want >>>> to consider instead of power to remove cycles from the picture. >>>> Take a look at src/mem/ruby/network/orion/NetworkPower.cc where the energy >>>> and power calculations are done. >>>> For a relative comparison, the numbers from Orion might work for you... >>>> You could compare the energy numbers for each component from Orion and >>>> DSENT if you want to see how much they differ. >>>> >>>> The cache sizes are in configs/common/Options.py >>>> >>>> >>>> On 09/12/2012 03:26 PM, Pavan Poluri wrote: >>>>> >>>>> Hi Tushar, >>>>> >>>>> The simulation ran for 5,400,912,679 cycles. How do I reduce the cache >>>>> sizes? Which source files do I need to modify? >>>>> >>>>> I was also looking into DSENT tool. To the extent I understood, the >>>>> current version of DSENT does not model the power of the Virtual Channel >>>>> Allocation stage. It only models the power for buffer, crossbar, switch >>>>> allocator and clock. I really need to calculate the power of the Virtual >>>>> Channel Allocation stage. >>>>> >>>>> Thanks for your help. >>>>> >>>>> Thanks, >>>>> Pavan >>>>> >>>>> On Wed, Sep 12, 2012 at 10:51 AM, Tushar Krishna <tus...@csail.mit.edu> >>>>> wrote: >>>>> Hi Pavan, >>>>> There are two issues here. >>>>> One, as Mitch pointed out, is that Orion is not entirely accurate. >>>>> I would suggest computing activity counts from garnet and feeding them to >>>>> DSENT. >>>>> >>>>> However, I have a feeling you will see a similar phenomenon (dynamic >>>>> power >> leakage power) even with DSENT. >>>>> How many cycles did your simulation run for? >>>>> For full system runs in gem5, the network activity is typically very low >>>>> (since network gets flits only on cache misses). >>>>> As a result your dynamic power is very low. >>>>> Network activity can be increased by reducing cache sizes. >>>>> >>>>> cheers, >>>>> Tushar >>>>> >>>>> >>>>> On Sep 12, 2012, at 1:43 PM, Pavan Poluri wrote: >>>>> >>>>>> Hi, >>>>>> >>>>>> Thanks a lot for your detailed reply. >>>>>> >>>>>> Thanks, >>>>>> Pavan >>>>>> >>>>>> On Wed, Sep 12, 2012 at 10:32 AM, Mitch Hayenga >>>>>> <mitch.hayenga+g...@gmail.com> wrote: >>>>>> Hi, >>>>>> >>>>>> I wouldn't trust the power model. Garnet is based on Orion, which in >>>>>> the last year a few papers have shown to be quite inaccurate (mostly >>>>>> because its internal model doesn't scale some technology parameters >>>>>> properly). >>>>>> >>>>>> More Information: >>>>>> 1. Peh's group recently announced a more accurate power modeling tool >>>>>> called DSENT (https://sites.google.com/site/mitdsent/). In their paper >>>>>> they highlight many issues with Orion and (at the 45nm node) find it >>>>>> capable of being off by ~10x in power. >>>>>> >>>>>> 2. I published a WDDD paper on Orion showing my own brief investigation >>>>>> into why its power/area numbers seemed disconnected with reality. >>>>>> (http://www.ece.wisc.edu/~hayenga/papers/wddd2012_hayenga.pdf) >>>>>> >>>>>> Hope this helps. Maybe the version of Orion integrated with Ruby/gem5 >>>>>> has received some updates, but unless you've heard otherwise, I wouldn't >>>>>> trust it. >>>>>> >>>>>> >>>>>> On Wed, Sep 12, 2012 at 12:30 PM, Mitch Hayenga >>>>>> <mitch.haye...@gmail.com> wrote: >>>>>> Hi, >>>>>> >>>>>> I wouldn't trust the power model. Garnet is based on Orion, which in >>>>>> the last year a few papers have shown to be quite inaccurate (mostly >>>>>> because its internal model doesn't scale some technology parameters >>>>>> properly). >>>>>> >>>>>> More Information: >>>>>> 1. Peh's group recently announced a more accurate power modeling tool >>>>>> called DSENT (https://sites.google.com/site/mitdsent/). In their paper >>>>>> they highlight many issues with Orion and (at the 45nm node) find it >>>>>> capable of being off by ~10x in power. >>>>>> >>>>>> 2. I published a WDDD paper on Orion showing my own brief investigation >>>>>> into why its power/area numbers seemed disconnected with reality. >>>>>> (http://www.ece.wisc.edu/~hayenga/papers/wddd2012_hayenga.pdf) >>>>>> >>>>>> Hope this helps. Maybe the version of Orion integrated with Ruby/gem5 >>>>>> has received some updates, but unless you've heard otherwise, I wouldn't >>>>>> trust it. >>>>>> >>>>>> >>>>>> On Wed, Sep 12, 2012 at 12:07 PM, Pavan Poluri <poluripa...@gmail.com> >>>>>> wrote: >>>>>> Hello, >>>>>> >>>>>> I have executed the Blackscholes application of the PARSEC benchmark >>>>>> suite with 16 threads on the input file set (in_4.txt) with a full >>>>>> system simulation with 16 cores, 16 L2 caches and 16 directories on a >>>>>> mesh topology with 4 rows. I have used the MOESI_CMP_directory protocol. >>>>>> The technology used is 90nm with a clock frequency of 1GHz and operating >>>>>> voltage VDD of 1.2V. I was going through the power statistics in the >>>>>> ruby.stats file. The following are the power numbers from the simulation. >>>>>> >>>>>> Router Dynamic Power = 0.00710691 W => 0.4441 mW per router >>>>>> Router Static Power = 0.452366 W => 28.272 mW per router >>>>>> Router Clock Power = 0.541901 W >>>>>> >>>>>> I am confused with these power numbers. The dynamic power is very very >>>>>> less compared to the static power. I do not understand why the dynamic >>>>>> power is so low even when the simulation resulted in the injection of >>>>>> 75,899,868 flits and the successful reception of 75,899,865 flits. Am I >>>>>> doing something wrong with the simulation? Do I need to set some >>>>>> parameters for the power calculations? >>>>>> >>>>>> Thanks for your time. >>>>>> >>>>>> Thanks, >>>>>> Pavan >>>>>> >>>>>> _______________________________________________ >>>>>> gem5-users mailing list >>>>>> gem5-users@gem5.org >>>>>> http://m5sim.org/cgi-bin/mailman/listinfo/gem5-users >>>>>> >>>>>> >>>>>> >>>>>> -- >>>>>> Mitch Hayenga >>>>>> mitch.haye...@gmail.com >>>>>> >>>>>> >>>>>> _______________________________________________ >>>>>> 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 >>>>> >>>>> >>>>> _______________________________________________ >>>>> 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 >>> >>> >>> _______________________________________________ >>> 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 >> >> >> _______________________________________________ >> 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
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