From: Jakub Kicinski <kuba@kernel.org>
To: Jason Xing <kerneljasonxing@gmail.com>
Cc: davem@davemloft.net, edumazet@google.com, pabeni@redhat.com,
bjorn@kernel.org, magnus.karlsson@intel.com,
maciej.fijalkowski@intel.com, jonathan.lemon@gmail.com,
sdf@fomichev.me, ast@kernel.org, daniel@iogearbox.net,
hawk@kernel.org, john.fastabend@gmail.com, joe@dama.to,
willemdebruijn.kernel@gmail.com, bpf@vger.kernel.org,
netdev@vger.kernel.org, Jason Xing <kernelxing@tencent.com>
Subject: Re: [PATCH net-next v4] net: xsk: introduce XDP_MAX_TX_BUDGET setsockopt
Date: Tue, 24 Jun 2025 16:31:14 -0700 [thread overview]
Message-ID: <20250624163114.712a9c43@kernel.org> (raw)
In-Reply-To: <20250623021345.69211-1-kerneljasonxing@gmail.com>
On Mon, 23 Jun 2025 10:13:45 +0800 Jason Xing wrote:
> @@ -424,7 +421,9 @@ bool xsk_tx_peek_desc(struct xsk_buff_pool *pool, struct xdp_desc *desc)
> rcu_read_lock();
> again:
> list_for_each_entry_rcu(xs, &pool->xsk_tx_list, tx_list) {
> - if (xs->tx_budget_spent >= MAX_PER_SOCKET_BUDGET) {
> + int max_budget = READ_ONCE(xs->max_tx_budget);
> +
> + if (xs->tx_budget_spent >= max_budget) {
> budget_exhausted = true;
> continue;
> }
I still think you're mixing two very different things. In the generic
xmit path the value you're changing is a budget. But xsk_tx_peek_desc()
*does not* exit after the "per socket budget" gets spent. The per
socket budget only controls how many frames we pick from a single sock
before we move to the next. But if we run out of budget on all sockets
we give every socket a full budget again and start from the first one
again.
For the ZC case the true budget is set by the driver's NAPI loop.
--
pw-bot: cr
next prev parent reply other threads:[~2025-06-24 23:31 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-06-23 2:13 [PATCH net-next v4] net: xsk: introduce XDP_MAX_TX_BUDGET setsockopt Jason Xing
2025-06-24 23:31 ` Jakub Kicinski [this message]
2025-06-25 0:19 ` Jason Xing
2025-06-25 12:21 ` Maciej Fijalkowski
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