On Wed, 12 Dec 2012, hanfeng QIN wrote:
Hi all,
I learn a common multi-programmed simulation methodology adopted by many
architecture researchers. But I am not clear its implementation internals. I
describe its idea in brief as following.
For multi-programmed workload consists of M programs, this methodology
firstly fast-forwards N1 instructions. Before detailed measurement, it warms
up cache with N2 instruction. Then detailed simulation is carried out until
all programs execute N3 instructions. Statistics reports only for the first
N3 instructions in detailed simulation.
I want to know how to implement it with Gem5 in practice. As far as I know,
gem5 provides '-s' option to support mode switch from TimingSimpleCPU to
DetailedCPU (O3). However, I have no idea to control each program to execute
fixed N3 instructions. Besides, if some programs finish retiring N3
instructions before others, how to dump the stats to assure it is correct for
all programs that have executed N3 instructions.
If you are programs run long enough, then you would be able to take the
required measurements before any one of them finishes. Instead of trying
to force each program to execute a fixed number of instructions, you can
force each program to execute a minimum number of instructions during
fast-forward, cache warmup and detailed simulation modes. So when all the
programs have executed at least N1 instructions, then only you should
switch the CPU. Similarly, when all the programs have executed at least N2
instructions, reset the statistics and start the detailed simulation.
If you look in to how the options -F and -W are used in the file
configs/common/Simulation.py, you should be able to make it work for
multiple CPU system as well.
--
Nilay
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