adb logcat filter doesn't work

My Android application tries to log some runtime information with Log.i ("myTag", rtMsg)

According to Android developer documents, I will be able to use "adb logcat myTag:I" to filter those information. One can set a list of filters, and use white space to separate them, here I used a filter myTag:I, saying that I would like to get log entries
with tag "myTag" and priority level at least I.

However, I got too many spams. Later I figured out that those filters are connected by disjunction relation, and the default filter is "*:I", that's why I thought my filter did not work.

So how to fix? Easy~~

adb logcat -s myTag

(-s tries to set the default filter to silent, which is the highest priority level)