Richard Graham wrote:
Yes - it is polling volatile memory, so has to load from memory on every read.
Actually, it will poll in cache, and only load from memory when the cache coherency protocol invalidates the cache line. Volatile semantic only prevents compiler optimizations.
It does not matter much where the pages are (closer to reader or receiver) on NUMAs, as long as they are equally distributed among all sockets (ie the choice is consistent). Cache prefetching is slightly more efficient on local socket, so closer to reader may be a bit better.
Patrick
