user26493: When I use Stockfish, the "hashfull" value climbs up to 1000 and then stays there. I was wondering what this means.
The documentation says :
* hashfull <x> the hash is x permill full, the engine should send this info regularly
But this doesn't help me to understand what it means.

user27084: An engine's hash table is a data structure where the engine stores positions and evaluations which it already calculated.
The parameter hashfull tells what permille full the hash is, i.e. how full it is on a scale of 0-1000.  Hashfull 0 means that the hash is empty, no data is being stored.  Hashfull 1000 means that the hash is full, and no more data can be stored.
If the hash is always full, then the engine could perform better with a larger hash (if you have more memory available for this)

26493: <p>When I use Stockfish, the &quot;hashfull&quot; value climbs up to 1000 and then stays there. I was wondering what this means.</p>
<p>The documentation says :</p>
<p><code>* hashfull &lt;x&gt; the hash is x permill full, the engine should send this info regularly</code></p>
<p>But this doesn't help me to understand what it means.</p>
 27084: <p>An engine's <a href="https://chess.stackexchange.com/a/12663/27084">hash table</a> is a data structure where the engine stores positions and evaluations which it already calculated.</p>
<p>The parameter <em>hashfull</em> tells what permille full the hash is, i.e. how full it is on a scale of 0-1000.  Hashfull 0 means that the hash is empty, no data is being stored.  Hashfull 1000 means that the hash is full, and no more data can be stored.</p>
<p>If the hash is always full, then the engine could perform better with a larger hash (if you have more memory available for this)</p>
