From: Jakub Kicinski <kuba@kernel.org>
To: Jesper Dangaard Brouer <hawk@kernel.org>
Cc: Maciej Fijalkowski <maciej.fijalkowski@intel.com>,
bpf@vger.kernel.org, ast@kernel.org, daniel@iogearbox.net,
netdev@vger.kernel.org, magnus.karlsson@intel.com,
aleksander.lobakin@intel.com, ilias.apalodimas@linaro.org,
toke@redhat.com, lorenzo@kernel.org,
syzbot+ff145014d6b0ce64a173@syzkaller.appspotmail.com,
Ihor Solodrai <ihor.solodrai@linux.dev>,
Octavian Purdila <tavip@google.com>
Subject: Re: [PATCH v4 bpf 1/2] xdp: introduce xdp_convert_skb_to_buff()
Date: Tue, 28 Oct 2025 18:53:14 -0700 [thread overview]
Message-ID: <20251028185314.1ad62578@kernel.org> (raw)
In-Reply-To: <11142984-9bbe-4611-bbe7-fa5494036b8f@kernel.org>
On Tue, 28 Oct 2025 09:08:52 +0100 Jesper Dangaard Brouer wrote:
> > + xdp->rxq->mem.type = page_pool_page_is_pp(virt_to_head_page(xdp->data)) ?
> > + MEM_TYPE_PAGE_POOL : MEM_TYPE_PAGE_SHARED;
>
> We are slowly killing performance with these paper cuts. The
> information we are looking for should be available via skb->pp_recycle,
> but instead we go lookup the page to deref that memory. And plus the
> virt_to_head_page() is more expensive than virt_to_page().
>
> Why don't we check skb->pp_recycle first, and then fall-back to checking
> the page to catch the mentioned problems?
I still think _all_ frags which may end up here are from the per CPU PP
since we CoW the skbs. So:
DEBUG_NET_WARN_ON_ONCE(!skb->pp_recycle);
xdp->rxq->mem.type = MEM_TYPE_PAGE_POOL;
? It is legal to have pp and non-pp frags in a single skb AFAIK.
next prev parent reply other threads:[~2025-10-29 1:53 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-10-27 12:13 [PATCH v4 bpf 0/2] xdp: fix page_pool leaks Maciej Fijalkowski
2025-10-27 12:13 ` [PATCH v4 bpf 1/2] xdp: introduce xdp_convert_skb_to_buff() Maciej Fijalkowski
2025-10-27 14:31 ` Toke Høiland-Jørgensen
2025-10-28 8:08 ` Jesper Dangaard Brouer
2025-10-29 1:53 ` Jakub Kicinski [this message]
2025-10-29 11:26 ` Maciej Fijalkowski
2025-10-29 23:12 ` Jakub Kicinski
2025-10-27 12:13 ` [PATCH v4 bpf 2/2] veth: update mem type in xdp_buff Maciej Fijalkowski
2025-10-27 14:31 ` Toke Høiland-Jørgensen
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