[phsau]

I've also found that under these conditions kswapd will effectively consume all your CPU time. The time it spends running is probably proportional to your maximum memory too - in our case it parses through 500+GB of LRU. The blocking writeback behaviour can be managed effectively with dirty page writeback ratio tuning. You don't want to block trying to write 50GB to disk at once when you hit the high dirty page watermark.