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From: Jakub Kicinski <kuba@kernel.org>
To: Willem de Bruijn <willemdebruijn.kernel@gmail.com>
Cc: davem@davemloft.net, netdev@vger.kernel.org, edumazet@google.com,
	pabeni@redhat.com, almasrymina@google.com, hawk@kernel.org,
	ilias.apalodimas@linaro.org, dsahern@gmail.com,
	dtatulea@nvidia.com
Subject: Re: [PATCH net-next v2 08/15] net: page_pool: add nlspec for basic access to page pools
Date: Tue, 21 Nov 2023 12:37:21 -0800	[thread overview]
Message-ID: <20231121123721.03511a3d@kernel.org> (raw)
In-Reply-To: <655cf5c7874bd_378cc9294f4@willemb.c.googlers.com.notmuch>

On Tue, 21 Nov 2023 13:24:07 -0500 Willem de Bruijn wrote:
> Do you want to introduce a separate ID for page pools? That brings some
> issues regarding network namespace isolation.
> 
> As a user API, it is also possible (and intuitive?) to refer to a
> page_pool by (namespacified) ifindex plus netdev_rx_queue index,
> or napi_id.

That does not work for "destroyed" pools. In general, there is
no natural key for a page pool I can think of.

> In fairness, napi_id is also global, not per netns.
> 
> By iterating over "for_each_netdev(net, ..", dump already limits
> output to pools in the same netns and get only reports pools that
> match the netns.
> 
> So it's only a minor matter of visible numbering, and perhaps
> superfluous new id.

The IDs are not stable. Any reconfiguration of a device will create
a new page pool and therefore assign a new ID. So applications can't
hold onto the ID long term.

That said the only use case for exposing the ID right now is to
implement do/GET (since there is no other unique key). And manual debug
with drgn, but that doesn't require uAPI. So if you prefer strongly
I can drop the ID from the uAPI and do/GET support.

  reply	other threads:[~2023-11-21 20:37 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-11-21  0:00 [PATCH net-next v2 00/15] net: page_pool: add netlink-based introspection Jakub Kicinski
2023-11-21  0:00 ` [PATCH net-next v2 01/15] net: page_pool: split the page_pool_params into fast and slow Jakub Kicinski
2023-11-21  0:00 ` [PATCH net-next v2 02/15] net: page_pool: avoid touching slow on the fastpath Jakub Kicinski
2023-11-21  0:00 ` [PATCH net-next v2 03/15] net: page_pool: factor out uninit Jakub Kicinski
2023-11-21  0:00 ` [PATCH net-next v2 04/15] net: page_pool: id the page pools Jakub Kicinski
2023-11-21  0:00 ` [PATCH net-next v2 05/15] net: page_pool: record pools per netdev Jakub Kicinski
2023-11-21  0:00 ` [PATCH net-next v2 06/15] net: page_pool: stash the NAPI ID for easier access Jakub Kicinski
2023-11-21  0:00 ` [PATCH net-next v2 07/15] eth: link netdev to page_pools in drivers Jakub Kicinski
2023-11-21 13:13   ` kernel test robot
2023-11-21 21:25   ` kernel test robot
2023-11-21  0:00 ` [PATCH net-next v2 08/15] net: page_pool: add nlspec for basic access to page pools Jakub Kicinski
2023-11-21 18:24   ` Willem de Bruijn
2023-11-21 20:37     ` Jakub Kicinski [this message]
2023-11-21 21:33       ` Willem de Bruijn
2023-11-21 22:00         ` Jakub Kicinski
2023-11-21 22:49           ` David Ahern
2023-11-21 23:42             ` Jakub Kicinski
2023-11-21  0:00 ` [PATCH net-next v2 09/15] net: page_pool: implement GET in the netlink API Jakub Kicinski
2023-11-21  0:00 ` [PATCH net-next v2 10/15] net: page_pool: add netlink notifications for state changes Jakub Kicinski
2023-11-21  0:00 ` [PATCH net-next v2 11/15] net: page_pool: report amount of memory held by page pools Jakub Kicinski
2023-11-21  0:00 ` [PATCH net-next v2 12/15] net: page_pool: report when page pool was destroyed Jakub Kicinski
2023-11-21 20:45   ` Jesper Dangaard Brouer
2023-11-21 21:49     ` Jakub Kicinski
2023-11-22  8:53       ` Jesper Dangaard Brouer
2023-11-21  0:00 ` [PATCH net-next v2 13/15] net: page_pool: expose page pool stats via netlink Jakub Kicinski
2023-11-21  0:00 ` [PATCH net-next v2 14/15] net: page_pool: mute the periodic warning for visible page pools Jakub Kicinski
2023-11-21  0:00 ` [PATCH net-next v2 15/15] tools: ynl: add sample for getting page-pool information Jakub Kicinski
2023-11-22  1:31 ` [PATCH net-next v2 00/15] net: page_pool: add netlink-based introspection Jakub Kicinski
2023-11-22  8:45   ` Jesper Dangaard Brouer
2023-11-22  1:40 ` patchwork-bot+netdevbpf

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