From: Joe Damato <jdamato@fastly.com>
To: Stanislav Fomichev <sdf@fomichev.me>
Cc: netdev@vger.kernel.org, davem@davemloft.net, edumazet@google.com,
kuba@kernel.org, pabeni@redhat.com, linux-kernel@vger.kernel.org,
bpf@vger.kernel.org, horms@kernel.org, ast@kernel.org,
daniel@iogearbox.net, hawk@kernel.org, john.fastabend@gmail.com,
bjorn@kernel.org, magnus.karlsson@intel.com,
maciej.fijalkowski@intel.com, jonathan.lemon@gmail.com,
mkarsten@uwaterloo.ca, alazar@nvidia.com
Subject: Re: [PATCH net] xsk: Bring back busy polling support
Date: Thu, 9 Jan 2025 09:32:09 -0800 [thread overview]
Message-ID: <Z4AIGWGVrEfk1yvE@LQ3V64L9R2> (raw)
In-Reply-To: <20250109003436.2829560-1-sdf@fomichev.me>
On Wed, Jan 08, 2025 at 04:34:36PM -0800, Stanislav Fomichev wrote:
> Commit 86e25f40aa1e ("net: napi: Add napi_config") moved napi->napi_id
> assignment to a later point in time (napi_hash_add_with_id). This breaks
> __xdp_rxq_info_reg which copies napi_id at an earlier time and now
> stores 0 napi_id. It also makes sk_mark_napi_id_once_xdp and
> __sk_mark_napi_id_once useless because they now work against 0 napi_id.
> Since sk_busy_loop requires valid napi_id to busy-poll on, there is no way
> to busy-poll AF_XDP sockets anymore.
>
> Bring back the ability to busy-poll on XSK by resolving socket's napi_id
> at bind time. This relies on relatively recent netif_queue_set_napi,
> but (assume) at this point most popular drivers should have been converted.
> This also removes per-tx/rx cycles which used to check and/or set
> the napi_id value.
>
> Confirmed by running a busy-polling AF_XDP socket
> (github.com/fomichev/xskrtt) on mlx5 and looking at BusyPollRxPackets
> from /proc/net/netstat.
Thanks Stanislav for finding and fixing this.
I've CC'd Alex who reported a bug a couple weeks ago that might be
fixed by this change.
Alex: would you mind applying this patch to your tree to see if this
solves the issue you reported [1] ?
[1]: https://lore.kernel.org/netdev/DM8PR12MB5447837576EA58F490D6D4BFAD052@DM8PR12MB5447.namprd12.prod.outlook.com/
next prev parent reply other threads:[~2025-01-09 17:32 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-01-09 0:34 [PATCH net] xsk: Bring back busy polling support Stanislav Fomichev
2025-01-09 15:22 ` Magnus Karlsson
2025-01-09 16:43 ` Jakub Kicinski
2025-01-09 17:36 ` Joe Damato
2025-01-09 17:32 ` Joe Damato [this message]
2025-01-11 2:20 ` patchwork-bot+netdevbpf
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=Z4AIGWGVrEfk1yvE@LQ3V64L9R2 \
--to=jdamato@fastly.com \
--cc=alazar@nvidia.com \
--cc=ast@kernel.org \
--cc=bjorn@kernel.org \
--cc=bpf@vger.kernel.org \
--cc=daniel@iogearbox.net \
--cc=davem@davemloft.net \
--cc=edumazet@google.com \
--cc=hawk@kernel.org \
--cc=horms@kernel.org \
--cc=john.fastabend@gmail.com \
--cc=jonathan.lemon@gmail.com \
--cc=kuba@kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=maciej.fijalkowski@intel.com \
--cc=magnus.karlsson@intel.com \
--cc=mkarsten@uwaterloo.ca \
--cc=netdev@vger.kernel.org \
--cc=pabeni@redhat.com \
--cc=sdf@fomichev.me \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.