netdev - Re: [PATCH net-next v3 3/4] Extend napi threaded polling to allow kthread based busy polling

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <ec6e53a9-8d3e-4b83-b4d9-1f089920fe84@bp.renesas.com>
Date: Wed, 5 Feb 2025 09:08:23 +0000
From: Paul Barker <paul.barker.ct@...renesas.com>
To: Samiullah Khawaja <skhawaja@...gle.com>, Jakub Kicinski
 <kuba@...nel.org>, "David S . Miller" <davem@...emloft.net>,
 Eric Dumazet <edumazet@...gle.com>, Paolo Abeni <pabeni@...hat.com>,
 almasrymina@...gle.com
Cc: netdev@...r.kernel.org
Subject: Re: [PATCH net-next v3 3/4] Extend napi threaded polling to allow
 kthread based busy polling

On 05/02/2025 00:10, Samiullah Khawaja wrote:
> Add a new state to napi state enum:
> 
> - STATE_THREADED_BUSY_POLL
>   Threaded busy poll is enabled/running for this napi.
> 
> Following changes are introduced in the napi scheduling and state logic:
> 
> - When threaded busy poll is enabled through sysfs it also enables
>   NAPI_STATE_THREADED so a kthread is created per napi. It also sets
>   NAPI_STATE_THREADED_BUSY_POLL bit on each napi to indicate that we are
>   supposed to busy poll for each napi.
> 
> - When napi is scheduled with STATE_SCHED_THREADED and associated
>   kthread is woken up, the kthread owns the context. If
>   NAPI_STATE_THREADED_BUSY_POLL and NAPI_SCHED_THREADED both are set
>   then it means that we can busy poll.
> 
> - To keep busy polling and to avoid scheduling of the interrupts, the
>   napi_complete_done returns false when both SCHED_THREADED and
>   THREADED_BUSY_POLL flags are set. Also napi_complete_done returns
>   early to avoid the STATE_SCHED_THREADED being unset.
> 
> - If at any point STATE_THREADED_BUSY_POLL is unset, the
>   napi_complete_done will run and unset the SCHED_THREADED bit also.
>   This will make the associated kthread go to sleep as per existing
>   logic.
> 
> Signed-off-by: Samiullah Khawaja <skhawaja@...gle.com>
> Reviewed-by: Willem de Bruijn <willemb@...gle.com>
> ---
>  Documentation/ABI/testing/sysfs-class-net     |  3 +-
>  Documentation/netlink/specs/netdev.yaml       | 12 ++--
>  Documentation/networking/napi.rst             | 67 ++++++++++++++++-
>  .../net/ethernet/atheros/atl1c/atl1c_main.c   |  2 +-
>  drivers/net/ethernet/mellanox/mlxsw/pci.c     |  2 +-
>  drivers/net/ethernet/renesas/ravb_main.c      |  2 +-
>  drivers/net/wireless/ath/ath10k/snoc.c        |  2 +-
>  include/linux/netdevice.h                     | 20 ++++--
>  include/uapi/linux/netdev.h                   |  6 ++
>  net/core/dev.c                                | 72 ++++++++++++++++---
>  net/core/net-sysfs.c                          |  2 +-
>  net/core/netdev-genl-gen.c                    |  2 +-
>  net/core/netdev-genl.c                        |  2 +-
>  tools/include/uapi/linux/netdev.h             |  6 ++
>  14 files changed, 171 insertions(+), 29 deletions(-)

Please copy in the maintainers of the network drivers which have been changed.

For ravb,
Acked-by: Paul Barker <paul.barker.ct@...renesas.com>

-- 
Paul Barker
Download attachment "OpenPGP_0x27F4B3459F002257.asc" of type "application/pgp-keys" (3521 bytes)

Download attachment "OpenPGP_signature.asc" of type "application/pgp-signature" (237 bytes)