In EAP 7, and undertow as web server whole model is different from what was there in EAP6.
now everything is done with non blocking(NIO) IO which as result doesn't require such huge threads as they ware needed with blocking IO (BIO)
I would advise you to not change any config at start and run some perf test first to see if you even need any configuration change.
For example if your application spends lots of time in processing blocking requests (like servlets) than consider increasing task-max-threads which defines just that.
Thanks Tomaz Cerar.
Is there any limit on task-max-threads or we can increase this number to any extent if i see performance issue with default configuration ?
Also is there any relation b/w io-threads and task-max-threads, like if change task-max-threads should i need to change io-threads as well ?