Your DreamHost VPS, ps?????, has just exceeded the memory allocation that you've established. If left unchecked that behavior could begin to negatively impact the VPS services of every other customer on your server.
Based on the usage pattern that we've seen today, it's clear that you'd be best served by either working to reduce your memory footprint or simply increasing the amount of memory available to your VPS.
We've put together some documentation that can help you troubleshoot and even reduce your current memory usage:
Remember, you can visit https://panel.dreamhost.com/index.cgi?tree=vserver.usage to scale your memory allocation up (or down) whenever you'd like!
Strictly speaking, you don't HAVE to take any action right now, but if your memory usage continues to routinely exceed the allocation level you've specified, you may experience more brief periods of downtime as your services are restarted.
Thank you for choosing DreamHost!