On Jan 6, 2009, at 6:12 PM, Ryan Markley wrote:
> Hello I have several questions about the latencies in the class
> DRAMMemory of the file PhysicalMemory.py, I have seen the definition
> of the following parameters:
>
> act_lat = Param.Latency("5ns", "RAS to CAS delay")
> cas_lat = Param.Latency("5ns", "CAS delay")
> war_lat = Param.Latency("7.5ns", "write after read delay")
> pre_lat = Param.Latency("18ns", "precharge delay")
> dpl_lat = Param.Latency("7.5ns", "data in to precharge delay")
> trc_lat = Param.Latency("57.5ns", "row cycle delay")
The built-in DRAM system is completely borked, just so you know. The
latencies the code actually uses are ticks, but the interface still
gives it as cycles. Combined with a number of other issues.
>
>
> My problem is that I do not identify this parameters with the common
> timing parameters that I can get from memory manufacturers, such as,
> CL-tRCD-tRP-tRAS-.
To get a number of the parameters, you need to compute them from the
manufacturer specified parameters using information in the appropriate
JEDEC standard. This is not to say that the parameters in the built-in
module are correct, but the standards have every possible parameter
named, described, and detailed.
>
> I know that act_lat is tRCD, and cas_lat is CL, but can anyone please
> tell me what parameters are the rest tRPand tRAS?.
>
> Also I have checked the file dram.cc and in there I can see the timing
> parameters that I want, is a good idea change the parameters in the
> #defines and recompile?.
>
> And another question to use the class DRAMMemory instead of
> PhysicalMemory, do I need to go to the file FSConfig.py and change the
> line
Either that, or construct your own configuration.
>
> self.physmem = PhysicalMemory(range = AddrRange(mdesc.mem()),
> latency='180ns') to
> self.physmem = DRAMMemory()
>
> And finally where can I specify the size of the memory using the class
> DRAMMemory in Full System mode?. I have not seen any range parameter.
Since it derives from PhysicalMemory, they have all the same
parameters as it does. The range is set in exactly the same way.
>
> Thanks in advance for the help.
> _______________________________________________
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> [email protected]
> http://m5sim.org/cgi-bin/mailman/listinfo/m5-users
I have a mostly complete DRAMSim integration, but there are some
licensing issues that have yet to be worked out as far as distributing
it with M5. I can probably directly give you a copy of my patch, but I
do not have it collected at this time.
- Clint
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