I recently learned about the Current cache hit ratio log message in dispatcher logs.
But I can't find any good documentation on it. So I have a few questions:
I ask because I have an existing access log query that calculates the difference between dispatcher requests and publish instance requests only on paths where I know there is caching. I ignore servlet paths that do no caching, and I also ignore all requests other than 200s. With that calculation I get a higher hit ratio than what the dispatcher claims.
How much should I trust the dispatcher log calculation?
Cache Hit Ratio: This means your fetching from render level vs from cache is measured. You want to hit 80+ percent from cache, and you should follow the help here:
For common dispatcher log details:
AMS Dispatcher Manual
The ratio is calculated as (100 * req_hits / req_total) with
req_hits = # files delivered from cache
req_total = the total number of requests handled by the dispatcher
from this point of view the cache-hit ratio is the same if requests are blocked on dispatcher (not httpd!) or forwarded to publish. So the number is nice, but it's hard to draw meaningful conclusions from it.