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

Message

Michal Schmidt March 7, 2024, 10:25 p.m. UTC

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

Comments

Przemek Kitszel March 15, 2024, 7:29 a.m. UTC | #1

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 <[e-mail]>