[net-next,v3,0/6] tsnep: XDP socket zero-copy support

Message

Gerhard Engleder April 18, 2023, 7:04 p.m. UTC

Implement XDP socket zero-copy support for tsnep driver. I tried to
follow existing drivers like igc as far as possible. But one main
difference is that tsnep does not need any reconfiguration for XDP BPF
program setup. So I decided to keep this behavior no matter if a XSK
pool is used or not. As a result, tsnep starts using the XSK pool even
if no XDP BPF program is available.

Another difference is that I tried to prevent potentially failing
allocations during XSK pool setup. E.g. both memory models for page pool
and XSK pool are registered all the time. Thus, XSK pool setup cannot
end up with not working queues.

Some prework is done to reduce the last two XSK commits to actual XSK
changes.

v3:
- use __netif_tx_lock_bh() (Paolo Abeni)
- comment that rx->page_buffer is always zero terminated (Paolo Abeni)

v2:
- eliminate modulo op in TX/RX path (Maciej Fijalkowski)
- eliminate retval variable in tsnep_rx_alloc_zc() (Maciej Fijalkowski)
- scope variable entry within loop (Maciej Fijalkowski)
- use DMA_ATTR_SKIP_CPU_SYNC directly (Maciej Fijalkowski)
- union for page/xdp in tsnep_rx_entry (Maciej Fijalkowski)
- provide performance numbers (Maciej Fijalkowski)
- use xsk_buff_alloc_batch() (Maciej Fijalkowski)
- use xsk_tx_peek_release_desc_batch() (Maciej Fijalkowski)
- don't call tsnep_rx_reopen() if netdev is down
- init adapter pointer of queue only once

Gerhard Engleder (6):
  tsnep: Replace modulo operation with mask
  tsnep: Rework TX/RX queue initialization
  tsnep: Add functions for queue enable/disable
  tsnep: Move skb receive action to separate function
  tsnep: Add XDP socket zero-copy RX support
  tsnep: Add XDP socket zero-copy TX support

 drivers/net/ethernet/engleder/tsnep.h      |  16 +-
 drivers/net/ethernet/engleder/tsnep_main.c | 863 ++++++++++++++++++---
 drivers/net/ethernet/engleder/tsnep_xdp.c  |  66 ++
 3 files changed, 822 insertions(+), 123 deletions(-)

Comments

Fijalkowski, Maciej April 20, 2023, 8:19 p.m. UTC | #1

On Tue, Apr 18, 2023 at 09:04:53PM +0200, Gerhard Engleder wrote:
> Implement XDP socket zero-copy support for tsnep driver. I tried to
> follow existing drivers like igc as far as possible. But one main
> difference is that tsnep does not need any reconfiguration for XDP BPF
> program setup. So I decided to keep this behavior no matter if a XSK
> pool is used or not. As a result, tsnep starts using the XSK pool even
> if no XDP BPF program is available.
> 
> Another difference is that I tried to prevent potentially failing
> allocations during XSK pool setup. E.g. both memory models for page pool
> and XSK pool are registered all the time. Thus, XSK pool setup cannot
> end up with not working queues.
> 
> Some prework is done to reduce the last two XSK commits to actual XSK
> changes.

I had minor comments on two last patches, besides:
Reviewed-by: Maciej Fijalkowski <[e-mail]>

> 
> v3:
> - use __netif_tx_lock_bh() (Paolo Abeni)
> - comment that rx->page_buffer is always zero terminated (Paolo Abeni)
> 
> v2:
> - eliminate modulo op in TX/RX path (Maciej Fijalkowski)
> - eliminate retval variable in tsnep_rx_alloc_zc() (Maciej Fijalkowski)
> - scope variable entry within loop (Maciej Fijalkowski)
> - use DMA_ATTR_SKIP_CPU_SYNC directly (Maciej Fijalkowski)
> - union for page/xdp in tsnep_rx_entry (Maciej Fijalkowski)
> - provide performance numbers (Maciej Fijalkowski)
> - use xsk_buff_alloc_batch() (Maciej Fijalkowski)
> - use xsk_tx_peek_release_desc_batch() (Maciej Fijalkowski)
> - don't call tsnep_rx_reopen() if netdev is down
> - init adapter pointer of queue only once
> 
> Gerhard Engleder (6):
>   tsnep: Replace modulo operation with mask
>   tsnep: Rework TX/RX queue initialization
>   tsnep: Add functions for queue enable/disable
>   tsnep: Move skb receive action to separate function
>   tsnep: Add XDP socket zero-copy RX support
>   tsnep: Add XDP socket zero-copy TX support
> 
>  drivers/net/ethernet/engleder/tsnep.h      |  16 +-
>  drivers/net/ethernet/engleder/tsnep_main.c | 863 ++++++++++++++++++---
>  drivers/net/ethernet/engleder/tsnep_xdp.c  |  66 ++
>  3 files changed, 822 insertions(+), 123 deletions(-)
> 
> -- 
> 2.30.2
>

Gerhard Engleder April 21, 2023, 7:05 p.m. UTC | #2

On 20.04.23 22:19, Maciej Fijalkowski wrote:
> On Tue, Apr 18, 2023 at 09:04:53PM +0200, Gerhard Engleder wrote:
>> Implement XDP socket zero-copy support for tsnep driver. I tried to
>> follow existing drivers like igc as far as possible. But one main
>> difference is that tsnep does not need any reconfiguration for XDP BPF
>> program setup. So I decided to keep this behavior no matter if a XSK
>> pool is used or not. As a result, tsnep starts using the XSK pool even
>> if no XDP BPF program is available.
>>
>> Another difference is that I tried to prevent potentially failing
>> allocations during XSK pool setup. E.g. both memory models for page pool
>> and XSK pool are registered all the time. Thus, XSK pool setup cannot
>> end up with not working queues.
>>
>> Some prework is done to reduce the last two XSK commits to actual XSK
>> changes.
> 
> I had minor comments on two last patches, besides:
> Reviewed-by: Maciej Fijalkowski <[e-mail]>

I will add that tag to all commits.

Thank you for the review!

Gerhard