Re: [RFC] Interface for TCP Metrics

From: Julian Anastasov <ja@ssi.bg>
Date: Sun, 19 Aug 2012 14:42:15 +0300 (EEST)

- will use genl with TCP_METRICS_GENL_NAME "tcp_metrics",
TCP_METRICS_GENL_VERSION 0x01

Sounds good.

- provide dumpit method and one cmd to read metrics by exact addr,
will use TCP_METRICS_CMD_{GET,...} and TCP_METRICS_ATTR_xxx in
new file include/linux/tcp_metrics.h

Ok.

Eric thinks we can filter in userspace, but since it's so easy to
lookup entries in the kernel and the demux for that is already there,
I have no objections to have a bonafide netlink operation for
getting a single entry.

- Is command to delete cached entry needed? Delete will need
new rcu_head. Useful to flush the cache or to delete entries
with filter.

Having a way to flush the entire table is useful.  Specific entries,
is less useful.

- without support for delete cmd, may be we can add command to
reset entry with default values from dst?

- Where to put the new netlink code?
tcp_metrics_netlink.c
tcp_metrics_nl.c
or just in current tcp_metrics.c ?

Put it in tcp_metrics.c, that way we don't need to export any
internals.

- command to modify specific metric for addr, by name? Only
for tcpm_vals? If not locked?

	Do we need modify/delete/reset support or just read
support is enough? Comments?

I would say that you can support fancy things as long as new
locking constraints are not added.