One GC problem

Elastic Stack Elasticsearch
1

one of my gateway node is assiged 1 GB heap memory and the traffic is very little. but it happens long GC time by time. can anybody give any hints about it?
ES log:

[2016-06-23 03:53:01,518][WARN ][monitor.jvm              ] [gw_172.20.122.111:9202] [gc][young][1232891][28] duration [1s], collections [1]/[1.2s], total [1s]/[22.2s], memory [298.7mb]->[27.3mb]/[989.8mb], all_pools {[young] [273mb]->[1.9mb]/[273mb]}{[survivor] [1.1mb]->[764.3kb]/[34.1mb]}{[old] [24.6mb]->[24.6mb]/[682.6mb]}
[2016-06-23 16:56:01,792][WARN ][monitor.jvm              ] [gw_172.20.122.111:9202] [gc][young][1279864][29] duration [1.3s], collections [1]/[2.3s], total [1.3s]/[23.6s], memory [298.3mb]->[27.4mb]/[989.8mb], all_pools {[young] [272.9mb]->[2.1mb]/[273mb]}{[survivor] [764.3kb]->[697.2kb]/[34.1mb]}{[old] [24.6mb]->[24.6mb]/[682.6mb]}

os:
CentOS release 6.6 (Final)
2.6.32

JDK:
jdk1.8.0_60

2

It is freeing pretty much all of the memory. With a 1GB I expect a young GC to be way faster than that. I wonder if you are swapping?

3

how do I tell whether a running node swapping or not?