No idea; numCycles (and most other stats) should have been different if you
are using something other than an extremely simple (e.g., hello world)
workload. Check your configs to make sure you are running the ones you desire.
Regards,Daniel
Em quinta-feira, 23 de maio de 2019 17:33:00 GMT+2, Pooneh Safayenikoo
<[email protected]> escreveu:
Hi Daniel,
Thank you so much for your help. But, for all the benchmarks the performance
(based on "system.cpu.numCycles" and "system.cpu.committedInsts" in stats file)
of both BDI and uncompressed are the same for me. Actually, all the metrics of
cpu in the stats file are same for both of them. Do you know why it happens for
me due to different miss rate for L2 cache?
Many Thanks again!
Best,Pooneh
On Thu, May 23, 2019 at 6:58 AM Daniel Carvalho <[email protected]> wrote:
Hello Pooneh,
You can check papers that discuss turning on and off compression (among
others), for common explanations of the negative influence of compression in
some workloads. Here is an extract of one of my simulation results both for mcf
and geo mean of all SPEC 2017 benchmarks:
BDI on L3
system.switch_cpus.ipc
0.309029 # IPC: Instructions Per Cycle - 505.mcf_r
system.switch_cpus.ipc
0.829107 # IPC: Instructions Per Cycle - Geo mean
Uncompressedsystem.switch_cpus.ipc
0.310797 # IPC: Instructions Per Cycle -
505.mcf_rsystem.switch_cpus.ipc
0.823940 # IPC: Instructions Per Cycle - Geo mean
As you can see, even though compression has a negative impact on the IPC in
mcf, overall it can generate improvements (similar results are seen for the
miss rate).
Regards,Daniel
Em quarta-feira, 22 de maio de 2019 05:50:22 GMT+2, Pooneh Safayenikoo
<[email protected]> escreveu:
Hi,
I want to apply BDI compression on the L2 cache. So, I changed the config file
for the caches (gem5/configs/common/Caches.py) like following:
class L1Cache(Cache):
tags = BaseSetAssoc()
compressor = NULL
class L2Cache(Cache):
tags = CompressedTags()
compressor = BDI()
After that, I got the results for some SPEC benchmarks (I used a configuration
like BDI paper) to compare the L2 miss rate between this compression and
baseline (without applying BDI and CompressedTags). But, miss rate increases a
little for some benchmarks (like mcf and bzip). Why BDI has higher L2 miss
rate? I cannot make sense of it.
Many thanks for any help!
Best,Pooneh
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