From bef152db47debcd14cbacefc5767f6f026c4bc89 Mon Sep 17 00:00:00 2001 From: Joshua Hay Date: Tue, 30 Jun 2026 16:56:19 -0700 Subject: [PATCH] idpf: adjust TxQ ring count minimum Set the TxQ ring count minimum to 128 descriptors. Any lower than this, and the queue will stall and trigger Tx timeouts in flow based scheduling mode. This is because next_to_clean might never be updated. In flow based scheduling mode, next_to_clean is only updated after a descriptor completion is processed, i.e. after the RE bit is set in the last descriptor of a Tx packet. This will never happen with a ring size of 64 and an IDPF_TX_SPLITQ_RE_MIN_GAP of 64. No matter what the value of last_re is initialized/set to, the calculated gap will be at most 63 and never trigger the RE bit. Even a ring size of 96 does not solve this. Because of how infrequent next_to_clean is updated and how small the ring is, IDPF_DESC_UNUSED will be much smaller on average. This increases the chance the queue will be stopped because a multi-descriptor packet, e.g. a large LSO packet, does not see enough resources on the ring. In this case, the queue will trigger the stop logic. The queue permanently stalls because there is no chance for a descriptor completion to update next_to_clean since it is dependent on a packet being sent. Fixes: 5f417d551324 ("idpf: replace flow scheduling buffer ring with buffer pool") Signed-off-by: Joshua Hay Reviewed-by: Aleksandr Loktionov Tested-by: Samuel Salin Signed-off-by: Tony Nguyen --- drivers/net/ethernet/intel/idpf/idpf_txrx.c | 5 +---- drivers/net/ethernet/intel/idpf/idpf_txrx.h | 2 +- 2 files changed, 2 insertions(+), 5 deletions(-) diff --git a/drivers/net/ethernet/intel/idpf/idpf_txrx.c b/drivers/net/ethernet/intel/idpf/idpf_txrx.c index 7f9056404f64f..c724d429a7aa9 100644 --- a/drivers/net/ethernet/intel/idpf/idpf_txrx.c +++ b/drivers/net/ethernet/intel/idpf/idpf_txrx.c @@ -3097,10 +3097,7 @@ static netdev_tx_t idpf_tx_splitq_frame(struct sk_buff *skb, tx_params.dtype = IDPF_TX_DESC_DTYPE_FLEX_FLOW_SCHE; tx_params.eop_cmd = IDPF_TXD_FLEX_FLOW_CMD_EOP; - /* Set the RE bit to periodically "clean" the descriptor ring. - * MIN_GAP is set to MIN_RING size to ensure it will be set at - * least once each time around the ring. - */ + /* Set the RE bit periodically to "clean" the descriptor ring */ if (idpf_tx_splitq_need_re(tx_q)) { tx_params.eop_cmd |= IDPF_TXD_FLEX_FLOW_CMD_RE; tx_q->txq_grp->num_completions_pending++; diff --git a/drivers/net/ethernet/intel/idpf/idpf_txrx.h b/drivers/net/ethernet/intel/idpf/idpf_txrx.h index 4be5b3b6d3ed2..908dfa28674eb 100644 --- a/drivers/net/ethernet/intel/idpf/idpf_txrx.h +++ b/drivers/net/ethernet/intel/idpf/idpf_txrx.h @@ -21,7 +21,7 @@ /* Mailbox Queue */ #define IDPF_MAX_MBXQ 1 -#define IDPF_MIN_TXQ_DESC 64 +#define IDPF_MIN_TXQ_DESC 128 #define IDPF_MIN_RXQ_DESC 64 #define IDPF_MIN_TXQ_COMPLQ_DESC 256 #define IDPF_MAX_QIDS 256 -- 2.47.3