Got ya! I think this should be included in GEMS wiki.
I am wondering how many systems have different clock
domains for processor and cache (not memory). But
thinking it that way is certainly OK.
On Fri, 04 Mar 2005 Milo Martin wrote :
> Min and others -
>
> Concerning the OPAL_RUBY_MULTIPLIER and the SIMICS_RUBY_MULTIPLIER
> variables. In many systems the memory system runs at a different
> frequency than the memory system. In GEMS, these two multiplier
> variables allow such a ratio of clocks. In general, I like to think of
> the memory system latencies as specified in nanoseconds, and the
> OPAL_RUBY_MULTIPLIER as determining the processor frequency. For
> example, an OPAL_RUBY_MULTIPLIER of 1, 2 and 4 would specify processor
> frequencies of 1Ghz, 2GHz, and 4Ghz, respectively. In essence, this
> allows the processor frequency to change with needing assume that DRAM
> latencies also changed.
>
> - Milo
>
> On Mar 4, 2005, at 12:35 PM, Min Xu (Hsu) wrote:
>
> >Weihang,
> >
> >You are right. There are two MULTIPLIERs in ruby. I don't know why
> >both of them are set to 2 by default. Can someone else shine some
> >light here?
> >
> >Hi group,
> >
> >Bk tells me both parameters are changed by milo in revision 1.28
> >at Feb 03 2004. The comment simply says it "makes more sense" to
> >have both MULTIPLIER be 2, instead of SIMICS_RUBY_MULTIPIER
> >be 4 and OPAL_RUBY_MULTIPLIER be 1.
> >
> >BTW, I found in opal/system/system.C:1894, there is another
> >"SIMICS_MULTIPLIER" constant, which seems to has something
> >to do with tracing. I wonder if the name for the constant
> >is too general. Should we rename it to some more specific
> >name?
> >
> >-Min
> >
> >On Fri, 04 Mar 2005 Weihang Jiang wrote :
> >>Thank you so much, Min :)
> >>
> >>One last question about this thread. I found two similar parameters:
> >>SIMICS_RUBY_MULTIPLIER: and OPAL_RUBY_MULTIPLIER.
> >>
> >>I assume you were referring to the one of these. So my question is
> >>what the other one is.
> >>
> >>Acutually, I am not very sure how to use ruby/opal for multi-processor
> >>simulation.
> >>
> >>What I did is following "QuickStart":
> >>ruby0.setparam g_NUM_PROCESSORS 2
> >>ruby0.init
> >>opal0.init
> >>
> >>It is correct?
> >>
> >>On Fri, 4 Mar 2005 00:32:55 -0600, Min Xu (Hsu) <xu@xxxxxxxxxxx>
> >>wrote:
> >>>Weihang,
> >>>
> >>>First question first, the multiplier is used to allow us to
> >>>use the in-order simics cpu model to approximate a N-way issue
> >>>super-scalar processor. In other words, every ruby cycle, we
> >>>could allow N-instructions to be executed in simics.
> >>>
> >>>However, when running with opal, the multiplier should be set
> >>>to 1, because every opal cycle, up to X number of instructions
> >>>are executed. There is no need to allow opal advance N cycles
> >>>for every 1 ruby cycle, unless you want to simulate a slower
> >>>memory somehow.
> >>>
> >>>As to your second question, when opal is running with ruby,
> >>>its own cache model is not used. So the parameters you listed
> >>>are safe to ignore. The only case where opal's own cache model
> >>>is used is when running single processor simulation without
> >>>ruby. Opal's own cache model doesn't support coherence yet.
> >>>
> >>>-Min
> >>>
> >>>On Thu, 03 Mar 2005 Weihang Jiang wrote :
> >>>>One related question:
> >>>>opal0.listparam lists configuration related to Memory System:
> >>>>
> >>>>IL1_ASSOC : 1
> >>>>IL1_SET_BITS : 8
> >>>>IL1_BLOCK_BITS : 6
> >>>>IL1_MSHR_ENTRIES : 256
> >>>>IL1_STREAM_BUFFERS : 0
> >>>>IL1_IDEAL : 0
> >>>>IL1_NL_TYPE : 0
> >>>>IL1_NL_LINES : 0
> >>>>IL1_MSHR_QUEUE_SIZE : 32
> >>>>IL1_MSHR_QUEUE_ISSUE_WIDTH : 2
> >>>>DL1_ASSOC : 1
> >>>>DL1_SET_BITS : 8
> >>>>DL1_BLOCK_BITS : 6
> >>>>DL1_MSHR_ENTRIES : 256
> >>>>DL1_STREAM_BUFFERS : 0
> >>>>DL1_IDEAL : 0
> >>>>L2_ASSOC : 4
> >>>>L2_SET_BITS : 12
> >>>>L2_BLOCK_BITS : 6
> >>>>L2_MSHR_ENTRIES : 128
> >>>>L2_STREAM_BUFFERS : 0
> >>>>L2_LATENCY : 6
> >>>>L2_IDEAL : 0
> >>>>MEMORY_DRAM_LATENCY : 80
> >>>>
> >>>>Most of them can also be found in ruby. Do I need to unify these
> >>>>values between ruby and opal? Or it is only useful when opal is used
> >>>>alone?
> >>>>
> >>>>
> >>>>On Thu, 3 Mar 2005 21:58:28 -0600, Weihang Jiang
> >>>><weihang.jiang@xxxxxxxxx> wrote:
> >>>>>Min:
> >>>>>Yes, it has been set to 2. What is the exact use of "multiplier"?
> >>>>>When
> >>>>>should it be used?
> >>>>>
> >>>>>Thanks
> >>>>>
> >>>>>
> >>>>>On Thu, 3 Mar 2005 21:06:19 -0600, Min Xu (Hsu) <xu@xxxxxxxxxxx>
> >>>>>wrote:
> >>>>>>Weihang,
> >>>>>>
> >>>>>>I notice the opal cycle is exactly twice of the ruby cycle.
> >>>>>>I think the difference came from the ruby/opal multiplier.
> >>>>>>Did you set the multiplier to 2?
> >>>>>>
> >>>>>>-Min
> >>>>>>
> >>>>>>On Thu, 03 Mar 2005 Weihang Jiang wrote :
> >>>>>>>Hi,
> >>>>>>> opal0.cycle tells me that "The current cycle is: 228737428".
> >>>>>>>But
> >>>>>>>ruby0.dump-stats tells
> >>>>>>>me that "Ruby_cycles: 114368714". Why?
> >>>>>>>
> >>>>>>>
> >>>>>>>
> >>>>>>>
> >>>>>>>--
> >>>>>>>Weihang Jiang
> >>>>>>>_______________________________________________
> >>>>>>>Gems-users mailing list
> >>>>>>>Gems-users@xxxxxxxxxxx
> >>>>>>>https://lists.cs.wisc.edu/mailman/listinfo/gems-users
> >>>>>>_______________________________________________
> >>>>>>Gems-users mailing list
> >>>>>>Gems-users@xxxxxxxxxxx
> >>>>>>https://lists.cs.wisc.edu/mailman/listinfo/gems-users
> >>>>>>
> >>>>>
> >>>>>--
> >>>>>Weihang Jiang
> >>>>>
> >>>>
> >>>>
> >>>>--
> >>>>Weihang Jiang
> >>>_______________________________________________
> >>>Gems-users mailing list
> >>>Gems-users@xxxxxxxxxxx
> >>>https://lists.cs.wisc.edu/mailman/listinfo/gems-users
> >>>
> >>
> >>
> >>--
> >>Weihang Jiang
> >_______________________________________________
> >Gems-users mailing list
> >Gems-users@xxxxxxxxxxx
> >https://lists.cs.wisc.edu/mailman/listinfo/gems-users
> >
> --
> Milo M. K. Martin (milom@xxxxxxxxxxxxx)
> http://www.cis.upenn.edu/~milom/
> Assistant Professor
> Computer and Information Sciences Department
> University of Pennsylvania
>
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