mpool
  "maxmempool": xxxxx,         (numeric) Maximum memory usage for the mempool
  "mempoolminfee": xxxxx       (numeric) Minimum fee rate in BTC/kB for tx to be accepted. Is the maximum of minrelaytxfee and minimum mempool fee
  "minrelaytxfee": xxxxx       (numeric) Current minimum relay fee for transactions
}

Examples:
> bitcoin-cli getmempoolinfo 
> curl --user myusername --data-binary '{"jsonrpc": "1.0", "id":"curltest", "method": "getmempoolinfo", "params": [] }' -H 'content-type: text/plain;' htt