Re: [PATCH net-next] amd-xgbe: schedule NAPI on Rx Buffer Unavailable to prevent RX stalls
From: Jakub Kicinski <kuba@kernel.org>
Date: 2025-11-27 03:13:44
On Mon, 24 Nov 2025 15:41:11 +0530 Raju Rangoju wrote:
When Rx Buffer Unavailable (RBU) interrupt is asserted, the device can stall under load and suffer prolonged receive starvation if polling is not initiated. Treat RBU as a wakeup source and schedule the appropriate NAPI instance (per-channel or global) to promptly recover from buffer shortages and refill descriptors.
You need to say more.. Under heavy load network devices will routinely run out of Rx buffers, it's expected if Rx processing is slower than the network. What hw condition and scenario exactly are you describing here?
dma_ch_isr = XGMAC_DMA_IOREAD(channel, DMA_CH_SR); + /* Precompute flags once */ + ti = !!XGMAC_GET_BITS(dma_ch_isr, DMA_CH_SR, TI); + ri = !!XGMAC_GET_BITS(dma_ch_isr, DMA_CH_SR, RI); + rbu = !!XGMAC_GET_BITS(dma_ch_isr, DMA_CH_SR, RBU); + fbe = !!XGMAC_GET_BITS(dma_ch_isr, DMA_CH_SR, FBE);
Please split this into two patches, one pure refactoring with no functional changes and second one changing RBU handling.
+ if (rbu) {
+ schedule_napi = true;
+ pdata->ext_stats.rx_buffer_unavailable++;
+ netif_dbg(pdata, intr, pdata->netdev,
+ "RBU on DMA_CH %u, scheduling %s NAPI\n",
+ i, per_ch_irq ? "per-channel" : "global");I guess it's just _dbg() but as a general rule when the system is under overload printing stuff (potentially over UART) is the last thing you should be doing. How is this print useful to you? -- pw-bot: cr