linux-kernel - [PATCH net-next 06/16] idpf: a use saner limit for default number of queues to allocate

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Message-ID: <20250305162132.1106080-7-aleksander.lobakin@intel.com>
Date: Wed,  5 Mar 2025 17:21:22 +0100
From: Alexander Lobakin <aleksander.lobakin@...el.com>
To: intel-wired-lan@...ts.osuosl.org
Cc: Alexander Lobakin <aleksander.lobakin@...el.com>,
	Michal Kubiak <michal.kubiak@...el.com>,
	Maciej Fijalkowski <maciej.fijalkowski@...el.com>,
	Tony Nguyen <anthony.l.nguyen@...el.com>,
	Przemek Kitszel <przemyslaw.kitszel@...el.com>,
	Andrew Lunn <andrew+netdev@...n.ch>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>,
	Paolo Abeni <pabeni@...hat.com>,
	Alexei Starovoitov <ast@...nel.org>,
	Daniel Borkmann <daniel@...earbox.net>,
	Jesper Dangaard Brouer <hawk@...nel.org>,
	John Fastabend <john.fastabend@...il.com>,
	Simon Horman <horms@...nel.org>,
	bpf@...r.kernel.org,
	netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH net-next 06/16] idpf: a use saner limit for default number of queues to allocate

Currently, the maximum number of queues available for one vport is 16.
This is hardcoded, but then the function calculating the optimal number
of queues takes min(16, num_online_cpus()).
On order to be able to allocate more queues, which will be then used for
XDP, stop hardcoding 16 and rely on what the device gives us. Instead of
num_online_cpus(), which is considered suboptimal since at least 2013,
use netif_get_num_default_rss_queues() to still have free queues in the
pool.
nr_cpu_ids number of Tx queues are needed only for lockless XDP sending,
the regular stack doesn't benefit from that anyhow.
On a 128-thread Xeon, this now gives me 32 regular Tx queues and leaves
224 free for XDP (128 of which will handle XDP_TX, .ndo_xdp_xmit(), and
XSk xmit when enabled).

Signed-off-by: Alexander Lobakin <aleksander.lobakin@...el.com>
---
 drivers/net/ethernet/intel/idpf/idpf_txrx.c     | 8 +-------
 drivers/net/ethernet/intel/idpf/idpf_virtchnl.c | 2 +-
 2 files changed, 2 insertions(+), 8 deletions(-)

diff --git a/drivers/net/ethernet/intel/idpf/idpf_txrx.c b/drivers/net/ethernet/intel/idpf/idpf_txrx.c
index c15833928ea1..2f221c0abad8 100644
--- a/drivers/net/ethernet/intel/idpf/idpf_txrx.c
+++ b/drivers/net/ethernet/intel/idpf/idpf_txrx.c
@@ -1234,13 +1234,7 @@ int idpf_vport_calc_total_qs(struct idpf_adapter *adapter, u16 vport_idx,
 		num_req_tx_qs = vport_config->user_config.num_req_tx_qs;
 		num_req_rx_qs = vport_config->user_config.num_req_rx_qs;
 	} else {
-		int num_cpus;
-
-		/* Restrict num of queues to cpus online as a default
-		 * configuration to give best performance. User can always
-		 * override to a max number of queues via ethtool.
-		 */
-		num_cpus = num_online_cpus();
+		u32 num_cpus = netif_get_num_default_rss_queues();
 
 		dflt_splitq_txq_grps = min_t(int, max_q->max_txq, num_cpus);
 		dflt_singleq_txqs = min_t(int, max_q->max_txq, num_cpus);
diff --git a/drivers/net/ethernet/intel/idpf/idpf_virtchnl.c b/drivers/net/ethernet/intel/idpf/idpf_virtchnl.c
index 3d2413b8684f..135af3cc243f 100644
--- a/drivers/net/ethernet/intel/idpf/idpf_virtchnl.c
+++ b/drivers/net/ethernet/intel/idpf/idpf_virtchnl.c
@@ -937,7 +937,7 @@ int idpf_vport_alloc_max_qs(struct idpf_adapter *adapter,
 	max_tx_q = le16_to_cpu(caps->max_tx_q) / default_vports;
 	if (adapter->num_alloc_vports < default_vports) {
 		max_q->max_rxq = min_t(u16, max_rx_q, IDPF_MAX_Q);
-		max_q->max_txq = min_t(u16, max_tx_q, IDPF_MAX_Q);
+		max_q->max_txq = min_t(u16, max_tx_q, IDPF_LARGE_MAX_Q);
 	} else {
 		max_q->max_rxq = IDPF_MIN_Q;
 		max_q->max_txq = IDPF_MIN_Q;
-- 
2.48.1