net: Kconfig: discourage drop_monitor enablement

Quoting Eric Dumazet:
"I do not understand the fascination with net/core/drop_monitor.c [..]
misses all the features, flexibility, scalability  that 'perf',
eBPF tracing, bpftrace, .... have today."

Reword DROP_MONITOR kconfig help text to clearly state that its not
related to perf-based drop monitoring and that its safe to disable
this unless support for the older netlink-based tools is needed.

Signed-off-by: Florian Westphal <[email protected]>
Reviewed-by: Simon Horman <[email protected]>
Reviewed-by: Eric Dumazet <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

Author: Florian Westphal

net/Kconfig

@@ -400,15 +400,15 @@ config NET_PKTGEN
 	  module will be called pktgen.
 
 config NET_DROP_MONITOR
-	tristate "Network packet drop alerting service"
+	tristate "Legacy network packet drop alerting service"
 	depends on INET && TRACEPOINTS
 	help
 	  This feature provides an alerting service to userspace in the
 	  event that packets are discarded in the network stack.  Alerts
 	  are broadcast via netlink socket to any listening user space
-	  process.  If you don't need network drop alerts, or if you are ok
-	  just checking the various proc files and other utilities for
-	  drop statistics, say N here.
+	  process. This feature is NOT related to "perf" based drop monitoring.
+	  Say N here unless you need to support older userspace tools like
+	  "dropwatch".
 
 endmenu # Network testing