Hi, I am running into a problem with one of my simulations where a functional read accss is failing. It is failing in this case because as the RubySystem is handling the functional accesses, it checks all the controllers in the system to determine which controllers have the block with the necesary permissions (RW/RO) and which have unavailable (I/BUSY).
For this specific case, the block is only valid in one cache, and is at the tme in 'M' state which has RW permission. Then, a L1_Replacement event is triggered in between the LOAD on M, and before the functional access completes, such that when the ruby system checks, it only finds one copy of the block, that copy being in MI (BUSY) state as it is being written back. Searching the list, it looks like this is a general (although rare) problem that can occur due to functional accesses coexisting with timing accesses: http://www.mail-archive.com/[email protected]/msg02126.html In solving that problem, the access permission of the WB state was changed to allow read permissions, but I am hesitant about doing that for the MI state in the MOESI_CMP_directory protocol, as it might have other negative effects. I am not using the latest latest dev repo (about a couple of months old), and I have made changes to the code, not any of which affects this behavior, it just exposed the problem. I have noticed a few others on the list have experienced similar problems, but no solution/response was ever posted. Any body have a better/cleaner idea than to change the access permissions of the MI State? Below is a snippet of the protocol trace/RubySystem flag: 2499502566500 0 L1Cache Load M>M [0x7510000, line 0x7510000] 2499527076000 0 L1Cache L1_Replacement M>MI [0x7510000, line 0x7510000] 2499527078000 0 L2Cache L1_PUTX ILX>ILXW [0x7510000, line 0x7510000] 2499527082000 0 L1Cache Writeback_Ack_Data MI>I [0x7510000, line 0x7510000] 2499527084000 0 L2Cache L1_WBDIRTYDATA ILXW>M [0x7510000, line 0x7510000] 2499530130500 0 Seq Begin > [0x7510000, line 0x7510000] LD 2499530132000 0 L1Cache Load I>IS [0x7510000, line 0x7510000] 2499530134000 0 L2Cache L1_GETS M>OO [0x7510000, line 0x7510000] 2499530136000 0 Seq Done > [0x7510000, line 0x7510000] 11 cycles 2499530136000 0 L1Cache Exclusive_Data IS>M_W [0x7510000, line 0x7510000] 2499530138000 0 L2Cache Exclusive_Unblock OO>ILX [0x7510000, line 0x7510000] 2499530161000 0 L1Cache Use_Timeout M_W>M [0x7510000, line 0x7510000] 2499531935500 0 Seq Begin > [0x7510000, line 0x7510000] LD 2499531937000 0 Seq Done > [0x7510000, line 0x7510000] 3 cycles 2499531937000 0 L1Cache Load M>M [0x7510000, line 0x7510000] 2499663708000: system.ruby: Functional Read request for [0x7510000, line 0x7510000] 2499663888000: system.ruby: Functional Read request for [0x7510000, line 0x7510000] 2499664653000 0 L1Cache L1_Replacement M>MI [0x7510000, line 0x7510000] 2499664661500: system.ruby: Functional Read request for [0x7510000, line 0x7510000] fatal: Ruby functional read failed for address 0x7510000 Malek
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