From: David Ahern <dsahern@gmail•com>
To: Stephen Hemminger <stephen@networkplumber•org>, netdev@vger•kernel.org
Cc: Stephen Hemminger <sthemmin@microsoft•com>
Subject: Re: [PATCH net-next] net: add network device notifier trace points
Date: Tue, 18 Dec 2018 20:38:48 -0700 [thread overview]
Message-ID: <3bb9fe50-87f9-a8b5-f886-9727d4e059e9@gmail.com> (raw)
In-Reply-To: <20181219022706.10611-1-sthemmin@microsoft.com>
On 12/18/18 7:27 PM, Stephen Hemminger wrote:
> There already are network trace points for transmit and receive but
> nothing for state changes. Add network tracepoints for before and
> after netlink callback is done. This is simple (without extack or
> other info) but that could be added if useful. Network namespace id
> would also be helpful but hard to get a string for it.
That has been a sore spot for a long time. One option is to allocate a
namespace id relative to init_net as every namespace is created and then
use the nsid in tracepoints.
>
> This is the result of a conversation about monitoring of link
> state changes with BPF. Parsing netlink is hard and unnecessary
> because the data exists (unserialized) already in the
> callbacks.
>
> # cd /sys/kernel/debug/tracing
> # echo 1 > events/net/net_dev_notifier_entry/enable
> # echo 1 > events/net/net_dev_notifier/enable
> # ip li set dev eno1 down
> # ip li set dev eno1 up
> # cat trace
> # tracer: nop
> #
> # _-----=> irqs-off
> # / _----=> need-resched
> # | / _---=> hardirq/softirq
> # || / _--=> preempt-depth
> # ||| / delay
> # TASK-PID CPU# |||| TIMESTAMP FUNCTION
> # | | | |||| | |
> ip-3194 [011] .... 74.926831: net_dev_notifier_entry: dev=eno1 event=GOING_DOWN
> ip-3194 [011] .... 74.926838: net_dev_notifier: dev=eno1 event=GOING_DOWN ret=1
naming the second one 'net_dev_notifier__exit' would align the columns,
make this a lot easier to read and better discriminate the entry/exit
difference.
next prev parent reply other threads:[~2018-12-19 3:38 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-19 2:27 [PATCH net-next] net: add network device notifier trace points Stephen Hemminger
2018-12-19 3:38 ` David Ahern [this message]
2018-12-19 7:36 ` Jesper Dangaard Brouer
2018-12-19 15:43 ` Stephen Hemminger
2018-12-19 15:46 ` Daniel Borkmann
2018-12-19 16:40 ` Jesper Dangaard Brouer
2018-12-19 16:55 ` Steven Rostedt
2018-12-19 17:07 ` Daniel Borkmann
2018-12-19 15:51 ` Steven Rostedt
2018-12-19 16:48 ` David Ahern
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