Hi all,
I have some questions about the tagged prefetcher. If I configure tagged
prefetcher in my simulation system, will it increase the amount of memory
accesses? If that is true, could I use a queue in PhysicalMemory to buffer lots
of packets without sending a packet back immediately after it arrives? I have
tried to buffer many packets after a long time execution, but the number of the
buffered packets in queue is at most 4. Is that caused by the strong data
dependency of benchmarks or the simulation mechanism of M5? By the way, I have
tried many benchmarks and all the results are the same. I wonder if I could
change the configuration file or some simulation mechanism to implement
buffering lots of packets in PhysicalMemory.
Another question is about the configuring to use prefetcher. I use
configs/example/se.py as my configuration file and I just modify the L1 cache
model as follows:
if options.caches:
system.cpu[i].addPrivateSplitL1Caches(
L1Cache(size’32kB',prefetch_policy='tagged',prefetch_miss='true'), L1Cache(size
= '64kB',prefetch_policy='tagged',prefetch_miss='true'))
Unfortunately, I get such information when I run M5 simulator:
………..
0: system.physmem: Write of size 8 on address 0x3802018 data 0x0
warn: Entering event queue @ 0. Starting simulation...
1000: global: system.cpu0.icache:Found a pf canidate, inserting into prefetch
queue
……………
28500: global: system.cpu0.dcache:Found a pf canidate, inserting into prefetch
queue
28500: global: system.cpu0.dcache:Found a pf canidate, inserting into prefetch
queue
29000: system.physmem: Read of size 64 on address 0x9b140
29000: global: system.cpu0.dcache:Marking a HW_PF in service
./run: line 17: 5371 Segmentation fault build/ALPHA_SE/m5.opt
--trace-flags="HWPrefetch,MemoryAccess" configs/example/se.py -d --caches -c
/home/pj/M5/m5/build/ALPHA_SE/spec/CFP2000/172.mgrid/exe/mgrid_base.gcc33-high-opt
-i /home/pj/M5/m5/build/ALPHA_SE/spec/CFP2000/172.mgrid/data/ref/input/mgrid.in
I have not modified source of M5, why does it get a segmentation faults? Is
there anything wrong with my configuration file? Is the TAGGED prefetcher the
only implemented prefetcher? Because when I use GHB and STRIDE and recompiled
the source, I get lots of errors.
Could anybody help me?
Thank you very much in advance!
Lei Yang
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