Hi Yuhang,
I suspect you call your routing function every cycle for every packet, causing
the massive slow down. You can always do a profiling run to figure out where
the time is spent. Build gem5.perf and use google perftools to analyse the
output, or use gem5.prof and analyse it with pprof.
Good luck.
Andreas
From: Yuhang <[email protected]<mailto:[email protected]>>
Reply-To: gem5 users mailing list
<[email protected]<mailto:[email protected]>>
Date: Thursday, 12 September 2013 18:25
To: gem5 users mailing list <[email protected]<mailto:[email protected]>>
Subject: [gem5-users] Odd even and adaptive routing didn't improve the
performance
Hello all,
I implemented odd even scheme and adaptive routing in garnet. For odd even, I
use the algorithm in the paper The odd-even turn model for adaptive routing
(Ge-Ming Chiu 2000). For adaptive routing, I use get_credit_cnt(vcs) for each
output to sum up all the credits in it, and choose the one with most credits. I
traced the flits flow, they work fine. However, the performance didn't improve
after the modification.
I ran FFT and LU kernels in splash2 with ALPHA MESI protocol, detailed cpu
type, 4*4 mesh, 1000000000 max ticks.
FFT with OE and adaptive routing FFT without OE and adaptive
RADIX with OE and adaptive RADIX without OE and adaptive
host_inst_rate 1006 11708 1945 15865
sim_insts 15008035 15016804 19748978 19752713
total flits injected 1315661 1309101 1131643 1130144
average latency 20.4676 20.4485 19.9921 19.968
Noticed that the host_inst_rate is extremely low with the implementation, and
the sim_insts even reduced a little bit. Is that because my modification is too
complex, so that each routing takes too many instructions? Or I just write the
codes wrong? I tried to reduce both l1 and l2 cache size to achieve higher
contention, but only got less than 1% improvement in sim_insts. In addition,
the benchmark runs very slow (usually take one day) with my modification and
reduced cache size. Could anyone give me some help with my issue?
Sincerely,
Yuhang
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