Subject: Re: [PATCH RFC net-next] net: drop_monitor: Add debugfs support

From: Florian Westphal <[email-masked]>
Date: Wed, 15 Oct 2025 13:14:47 +0200

Eric Dumazet <[email-masked]> wrote:
> I do not understand the fascination with net/core/drop_monitor.c,
> which looks very old school to me,
> and misses all the features,  flexibility, scalability  that 'perf',
> eBPF tracing, bpftrace, .... have today.
> 
> Adding  /sys/kernel/debug/drop_monitor/* is even more old school.
> 
> Not mentioning the maintenance burden.
> 
> For me the choice is easy :
> 
> # CONFIG_NET_DROP_MONITOR is not set
> 
> perf record -ag -e skb:kfree_skb sleep 1
> 
> perf script # or perf report

Maybe:

diff --git a/net/Kconfig b/net/Kconfig
--- a/net/Kconfig
+++ b/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".