I noticed today that the ARC statistics are maintained with atomic operations. (This is even called out in a comment, so it?s not a great insight.)
This seems like a potential scalability problem on multi-CPU systems. The cache line involved is going to bounce back and forth at a fairly high rate. These statistics should probably be kept on a per-CPU basis. (Nothing actually reads them right now, so the cost of aggregation is 0 at present. ;-) Switching to non-atomic operations doesn't buy a whole lot since the writes will force cache line exclusivity anyway. -- This messages posted from opensolaris.org
