netdev - Re: [PATCH net-next v3 0/3] ice: lighter locking for PTP time reading

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Date: Fri, 15 Mar 2024 08:29:41 +0100
From: Przemek Kitszel <przemyslaw.kitszel@...el.com>
To: Michal Schmidt <mschmidt@...hat.com>, <intel-wired-lan@...ts.osuosl.org>
CC: <netdev@...r.kernel.org>, Jacob Keller <jacob.e.keller@...el.com>, "Jakub
 Kicinski" <kuba@...nel.org>, Jiri Pirko <jiri@...nulli.us>, Jesse Brandeburg
	<jesse.brandeburg@...el.com>, Arkadiusz Kubalewski
	<arkadiusz.kubalewski@...el.com>, Karol Kolacinski
	<karol.kolacinski@...el.com>
Subject: Re: [PATCH net-next v3 0/3] ice: lighter locking for PTP time reading

On 3/7/24 23:25, Michal Schmidt wrote:
> This series removes the use of the heavy-weight PTP hardware semaphore
> in the gettimex64 path. Instead, serialization of access to the time
> register is done using a host-side spinlock. The timer hardware is
> shared between PFs on the PCI adapter, so the spinlock must be shared
> between ice_pf instances too.
> 
> Replacing the PTP hardware semaphore entirely with a mutex is also
> possible and you can see it done in my git branch[1], but I am not
> posting those patches yet to keep the scope of this series limited.
> 
> [1] https://gitlab.com/mschmidt2/linux/-/commits/ice-ptp-host-side-lock-9
> 
> v3:
>   - Longer variable name ("a" -> "adapter").
>   - Propagate xarray error in ice_adapter_get with ERR_PTR.
>   - Added kernel-doc comments for ice_adapter_{get,put}.
> 
> v2:
>   - Patch 1: Rely on xarray's own lock. (Suggested by Jiri Pirko)
>   - Patch 2: Do not use *_irqsave with ptp_gltsyn_time_lock, as it's used
>     only in process contexts.
> 
> Michal Schmidt (3):
>    ice: add ice_adapter for shared data across PFs on the same NIC
>    ice: avoid the PTP hardware semaphore in gettimex64 path
>    ice: fold ice_ptp_read_time into ice_ptp_gettimex64
> 
>   drivers/net/ethernet/intel/ice/Makefile      |   3 +-
>   drivers/net/ethernet/intel/ice/ice.h         |   2 +
>   drivers/net/ethernet/intel/ice/ice_adapter.c | 109 +++++++++++++++++++
>   drivers/net/ethernet/intel/ice/ice_adapter.h |  28 +++++
>   drivers/net/ethernet/intel/ice/ice_main.c    |   8 ++
>   drivers/net/ethernet/intel/ice/ice_ptp.c     |  33 +-----
>   drivers/net/ethernet/intel/ice/ice_ptp_hw.c  |   3 +
>   7 files changed, 156 insertions(+), 30 deletions(-)
>   create mode 100644 drivers/net/ethernet/intel/ice/ice_adapter.c
>   create mode 100644 drivers/net/ethernet/intel/ice/ice_adapter.h
> 

Reviewed-by: Przemek Kitszel <przemyslaw.kitszel@...el.com>