What's the meaning of "dirty" in Geth's INFO logs "Importing new chain segment..."

Question

I am trying to understand the logs I see when I journalctl -fu my Geth service, which I restarted after it was offline for two days. This is less a troubleshooting question and more an extension to this question: Meaning of Imported New Chain Segment

I can see (as expected) its INFO logs where it's importing the new chain segments. What I am wondering now - and I could not find this info anywhere on the web so far - is what the parameters at the end of the line mean. Specifically, mgas, mgasps and dirty?
Especially dirty increases the longer geth is running, what does it mean?

INFO [04-05|18:33:07.751] Imported new chain segment               blocks=5   txs=1117  mgas=62.453  elapsed=9.376s    mgasps=6.660  number=12156068 hash="e34b89…3f9846" age=3d19h2m   dirty=367.91MiB

I might have been just blind and missing some obvious documentation where this is explained, if that's the case, it would be wonderful if you could point me to the right place where this is documented!

Thanks a lot! :)

Answer 1

For the chain segment imported:

• mgas => Million gas involved in the associated transactions
• mgasps => Million gas per second (given the elapsed time for importing this chain segment)
• dirty => Given the transactions included in the imported chain segment, this is the size of the impacted chain state (i.e. the state that needs to be updated)