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lilli

If thread1 runs on P1 and thread2 runs on P2, and each thread runs only on data partitioned to each thread, we will still have problems if data cache lines stride across partitions.

Even though algorithmically, thread1 doesn't need to touch any data owned by thread2, it needs to grab the whole cache line on the boundaries. And then it needs to communicate with thread2 about the state of that cache line.

200

Do these processors still need to communicate with each other if there is no write operation on the shared cache line (read-only cache)?

jiangyifan2bad

@200 I don't think they need to in that case. The cache on processors will not be invalidated by each other, which means artifactual communication is unnecessary.

sandeep6189

Does anyone think "False sharing" is an example of artifactual communication?

lilli

@sandeep6189: Yes I think false sharing is an example of artifactual communication, since it is dependent upon the machine implementation details (cache size, etc).