Comment # 5 on bug 1013629 from Michal Hocko

(In reply to Howard Guo from comment #3)
> Created attachment 705801 [details]
> /proc/vmstat

this seems to be a single snapshot of the file. This won't help very much
because I would need to see how those counters evolve over time.

Could you do something like
mkdir logs
cd logs
while true
do
     cp /proc/vmstat vmstat.$(date +%s)
     sleep 1s
done

and note the time when the kswapd starts pegging the cpu?