Hi Fulya,
What's the L2 cache size of the 1-core test? Is it equal to the total capacity of 4-core case? The stats indicates that 4-core test has less L2 cache miss rate, which may be the reason of IPC improvement. -Tao From: [email protected] [mailto:[email protected]] On Behalf Of Fulya Kaplan Sent: Monday, November 04, 2013 10:20 AM To: gem5 users mailing list Subject: [gem5-users] Weird IPC statistics for Spec2006 Multiprogram mode Hi all, I am running Spec 2006 on X86 with the version gem5-stable-07352f119e48. I am using multiprogram mode with syscall emulation. I am trying to compare the IPC statistics for 2 cases: 1)Running benchmark A on a single core 2)Running 4 instances of benchmark A on a 4-core system with 1MB private L2 cashes. All parameters are the same for the 2 runs except the number of cores. I am expecting some IPC decrease for the 4-core case as the cores will share the same system bus. However, for CactusADM and Soplex benchmarks, I see higher IPC for case2 compared to case 1. I look at the same phase of execution for both runs. I fastforward for 2 billion instructions and grab the ipc for each of the cores corresponding to the next 100 million instructions in detailed mode. I ll report some other statistics for CactusADM to give a better idea of what is going on. Case 1: ipc=0.664141, L2_overall _accesses=573746, L2_miss_rate=0.616 Case 2: cpu0_ipc=0.718562, cpu1_ipc= 0.720464, cpu2_ipc=0.717405, cpu3_ipc= 0.716513 L2_0_accesses=591607, L2_1_accesses=581846, L2_2_accesses=568095, L2_3_accesses=561180, L2_0_missrate=0.452978, L2_1_missrate=0.454510, L2_2_missrate=0.475646, L2_3_missrate=0.488171 Case 1:Running Time for 100M insts = 0.0716 sec Case 2:Running Time for 100M insts = 0.066273 sec Do you have any idea what could be the problem? Actually, is this a problem or something expected for some benchmarks? Best, Fulya Kaplan
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