On 09/18/2011 07:16 PM, Mark Roos wrote:
In looking at my code.
In general 98% of the callsites are < 3 targets.
Those that are larger I can catch and use a different lookup. I also
believe that Charles Nutter limits his
depth to 5.
So the general case I see will not exceed the < 10.
But I do have some cases where 10 is not the right number
Part of my app is a compiler so some of its callsites see 20
or 30 classes ( AST node types).
And part is a data flow evaluator where the data has about 30
types
For these callsites you should use a dispatch table (a vtable dedicated
to a callsite)
instead of a sequence of 20 guards, because your code is equivalent to
looking up
a class in a linkedlist, so it's awfully slow.
Moreover, are you sure the code that contains these callsites is JITed,
it's pretty easy to hit other thresholds like by example
the max number of internal nodes (ideal nodes).
And as I watch the jit work it attacks these sites pretty fast so I
could image exceeding the > 10.
I would like both or these to jit as they are used a lot
And my final use case which is dynamic method replacement. Here I
have to reset the callsites so they
get the correct code. In our system this happens doing feature
loading ( small dynamic patches) and for
changing math operations ( dataflow) and finally during edit. Both
easily exceed the >10 during the execution
life of the app (hopefully months).
I would be fine if there was a way to tell the jitter to reset its
counts on a callsite as all of my use cases
can absorb time at that instance. I really would have issues with
losing the jitting when the app is expected
to be running at full speed and would have to find some clever hack
around it.
Another point is that the classes callsites see during startup can be
quite different than during normal operation.
This is another reason we do the bulk invalidation
mark
Rémi
_______________________________________________
mlvm-dev mailing list
mlvm-dev@openjdk.java.net
http://mail.openjdk.java.net/mailman/listinfo/mlvm-dev
