# Re: \[PATCH net-next v1 0/5\] net: deprecate skb-\>pp\_recycle and skb\_mark\_for\_recycle()

- From: Mina Almasry \<hidden\>
- Date: 2026-11-06 17:53:20 
- List: netdev
- Page: https://ratatoskr.run/netdev/2026/11/17880506
- Thread: https://ratatoskr.run/netdev/2026/11/17856127/t.md

```text
On Thu, Nov 5, 2026 at 8:36 AM Jesper Dangaard Brouer [ref] wrote:
>
>
>
> On 11/3/26 22:14, Mina Almasry wrote:
> > Remove the per-SKB skb->pp_recycle bitfield and skb_mark_for_recycle()
> > helper, and reference-count netmems directly by their underlying type
> > via netmem_is_pp() inside netmem_inc_ref() and netmem_dec_ref().
> >
> > This series simplifies SKB and netmem reference counting:
> > - Reclaims 1 bit from struct sk_buff (skb->pp_recycle).
> > - Unifies reference counting of SKB fragment netmems and regular netmems
> >    under netmem_inc_ref() and netmem_dec_ref(), eliminating the separate
> >    skb_netmem_ref(), skb_netmem_unref(), and skb_mark_for_recycle() APIs.
>
> Part of the performance gain from page_pool was to completely avoid the
> atomic refcnt operation, when we can see that page refcnt==1.
> Are you removing this?
>

I am not, and this is a very sharp observation, because retaining that
optimization was one of the things I struggled with my LLM to come up
with a way to retain that optimization without pp_recycle. Patch 4
includes verification from pp-bench that the fast path remains just as
fast:

   - no-softirq-page_pool01 (fast path): 37 cycles (18.7 ns) baseline
vs      36-37 cycles (18.5 ns) patched.
   - no-softirq-page_pool02 (ptr_ring): 77-78 cycles (38.9 ns)
baseline vs      76-77 cycles (38.4 ns) patched.

But the sashiko comments indicates there is at least 1 race related to
this we missed. It looks like a smp_rmb() after checking the page is
exclusively owned may fix it. Let me see if that works.

-- 
Thanks,
Mina
```