> On April 4, 2012, 9:23 p.m., Brad Beckmann wrote:
> > Hi Andreas,

Sorry it took me a couple weeks to look this patch over.  It is an impressive 
amount of work.  My biggest concern is it appears that this patch will break 
all existing checkpoints, correct?  Your comment states that a later patch will 
enable checkpoint migration between different NUMA layouts, but will it also 
support checkpoints created prior to this change?  Can you delay checking this 
patch in until that later patch with checkpoint support is ready to be checked 
in?

Thanks

Hi Brad,

Thanks :)

The checkpointing will continue to work just as usual with all your existing 
systems, as they only use one physmem, and that is not going to cause you any 
problems. At the moment, the serialize/unserialize is still part of each 
individual memory, so as long as they are not modified before/after the 
checkpoint it is "business as usual" even with multiple memories. Therefore I'd 
prefer to get this patch out as it is.

Later on, if we want to think about potential features to add, one would be to 
change the number and type of memories for different distributed memory 
layouts. That would require moving some intelligence into the "PhysicalMemory" 
wrapper now as it would have to "distribute" the state to the appropriate 
memories. This is an added function that should be a separate patch and I will 
try and add support for this on a "need to have" basis as there is currently a 
lot in the pipeline. I don't see it as critical to the current patch as it 
maintains current functionality.

Similarly, for the striping, I'm currently looking at how to improve the 
support for this in gem5. This will also be a separate patch and added later.

I hope that all makes sense and that we can commit this as it is.


- Andreas


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On April 2, 2012, 2:34 p.m., Andreas Hansson wrote:
> 
> -----------------------------------------------------------
> This is an automatically generated e-mail. To reply, visit:
> http://reviews.gem5.org/r/1113/
> -----------------------------------------------------------
> 
> (Updated April 2, 2012, 2:34 p.m.)
> 
> 
> Review request for Default.
> 
> 
> Description
> -------
> 
> MEM: Enable multiple distributed generalized memories
> 
> This patch removes the assumption on having on single instance of
> PhysicalMemory, and enables a distributed memory where the individual
> memories in the system are each responsible for a single contiguous
> address range.
> 
> All memories inherit from an AbstractMemory that encompasses the basic
> behaviuor of a random access memory, and provides untimed access
> methods. What was previously called PhysicalMemory is now
> SimpleMemory, and a subclass of AbstractMemory. All future types of
> memory controllers should inherit from AbstractMemory.
> 
> To enable e.g. the atomic CPU and RubyPort to access the now
> distributed memory, the system has a wrapper class, called
> PhysicalMemory that is aware of all the memories in the system and
> their associated address ranges. This class thus acts as an
> infinitely-fast bus and performs address decoding for these "shortcut"
> accesses. Each memory can specify that it should not be part of the
> global address map (used e.g. by the functional memories by some
> testers). Moreover, each memory can be configured to be reported to
> the OS configuration table, useful for populating ATAG structures, and
> any potential ACPI tables.
> 
> Checkpointing support currently assumes that all memories have the
> same size and organisation when creating and resuming from the
> checkpoint. A future patch will enable a more flexible
> re-organisation.
> 
> 
> Diffs
> -----
> 
>   configs/example/ruby_network_test.py 97f06a79b6f5 
>   configs/example/ruby_random_test.py 97f06a79b6f5 
>   configs/example/se.py 97f06a79b6f5 
>   configs/ruby/MESI_CMP_directory.py 97f06a79b6f5 
>   configs/ruby/MI_example.py 97f06a79b6f5 
>   configs/example/ruby_mem_test.py 97f06a79b6f5 
>   configs/example/ruby_direct_test.py 97f06a79b6f5 
>   configs/example/memtest.py 97f06a79b6f5 
>   configs/common/FSConfig.py 97f06a79b6f5 
>   configs/ruby/MOESI_CMP_directory.py 97f06a79b6f5 
>   configs/ruby/MOESI_CMP_token.py 97f06a79b6f5 
>   configs/ruby/MOESI_hammer.py 97f06a79b6f5 
>   configs/ruby/Network_test.py 97f06a79b6f5 
>   configs/ruby/Ruby.py 97f06a79b6f5 
>   configs/splash2/cluster.py 97f06a79b6f5 
>   configs/splash2/run.py 97f06a79b6f5 
>   src/arch/alpha/remote_gdb.hh 97f06a79b6f5 
>   src/arch/alpha/remote_gdb.cc 97f06a79b6f5 
>   src/arch/arm/ArmSystem.py 97f06a79b6f5 
>   src/arch/arm/linux/system.cc 97f06a79b6f5 
>   src/arch/arm/system.cc 97f06a79b6f5 
>   src/arch/sparc/SparcSystem.py 97f06a79b6f5 
>   src/base/remote_gdb.hh 97f06a79b6f5 
>   src/base/remote_gdb.cc 97f06a79b6f5 
>   src/cpu/checker/thread_context.hh 97f06a79b6f5 
>   src/cpu/inorder/thread_context.hh 97f06a79b6f5 
>   src/cpu/o3/fetch_impl.hh 97f06a79b6f5 
>   src/cpu/simple/atomic.hh 97f06a79b6f5 
>   src/cpu/simple/atomic.cc 97f06a79b6f5 
>   src/dev/alpha/backdoor.cc 97f06a79b6f5 
>   src/dev/arm/RealView.py 97f06a79b6f5 
>   src/mem/AbstractMemory.py PRE-CREATION 
>   src/mem/PhysicalMemory.py 97f06a79b6f5 
>   src/mem/SConscript 97f06a79b6f5 
>   src/mem/SimpleMemory.py PRE-CREATION 
>   src/mem/abstract_mem.hh PRE-CREATION 
>   src/mem/abstract_mem.cc PRE-CREATION 
>   src/mem/physical.hh 97f06a79b6f5 
>   src/mem/physical.cc 97f06a79b6f5 
>   src/mem/ruby/system/RubyPort.cc 97f06a79b6f5 
>   src/mem/simple_mem.hh PRE-CREATION 
>   src/mem/simple_mem.cc PRE-CREATION 
>   src/sim/System.py 97f06a79b6f5 
>   src/sim/system.hh 97f06a79b6f5 
>   src/sim/system.cc 97f06a79b6f5 
>   tests/configs/inorder-timing.py 97f06a79b6f5 
>   tests/configs/memtest-ruby.py 97f06a79b6f5 
>   tests/configs/memtest.py 97f06a79b6f5 
>   tests/configs/o3-timing-checker.py 97f06a79b6f5 
>   tests/configs/o3-timing-mp.py 97f06a79b6f5 
>   tests/configs/o3-timing.py 97f06a79b6f5 
>   tests/configs/rubytest-ruby.py 97f06a79b6f5 
>   tests/configs/simple-atomic-dummychecker.py 97f06a79b6f5 
>   tests/configs/simple-atomic-mp.py 97f06a79b6f5 
>   tests/configs/simple-atomic.py 97f06a79b6f5 
>   tests/configs/simple-timing-mp-ruby.py 97f06a79b6f5 
>   tests/configs/simple-timing-mp.py 97f06a79b6f5 
>   tests/configs/simple-timing-ruby.py 97f06a79b6f5 
>   tests/configs/simple-timing.py 97f06a79b6f5 
> 
> Diff: http://reviews.gem5.org/r/1113/diff/
> 
> 
> Testing
> -------
> 
> util/regress all passing (disregarding t1000 and eio)
> 
> 
> Thanks,
> 
> Andreas Hansson
> 
>

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