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Date: Mon, 5 Dec 2011 00:20:38 -0800 From: Jeff Kirsher <jeffrey.t.kirsher@...el.com> To: davem@...emloft.net Cc: Matthew Vick <matthew.vick@...el.com>, netdev@...r.kernel.org, gospo@...hat.com, sassmann@...hat.com, Jeff Kirsher <jeffrey.t.kirsher@...el.com> Subject: [net-next 3/6] igb: Update DMA Coalescing threshold calculation. From: Matthew Vick <matthew.vick@...el.com> This patch updates the DMA Coalescing feature parameters to account for larger MTUs. Previously, sufficient space may not have been allocated in the receive buffer, causing packet drop. Signed-off-by: Matthew Vick <matthew.vick@...el.com> Tested-by: Aaron Brown <aaron.f.brown@...el.com> Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@...el.com> --- drivers/net/ethernet/intel/igb/igb_main.c | 26 +++++++++++++++++++------- 1 files changed, 19 insertions(+), 7 deletions(-) diff --git a/drivers/net/ethernet/intel/igb/igb_main.c b/drivers/net/ethernet/intel/igb/igb_main.c index b66b8aa..143cfeb 100644 --- a/drivers/net/ethernet/intel/igb/igb_main.c +++ b/drivers/net/ethernet/intel/igb/igb_main.c @@ -7061,15 +7061,28 @@ static void igb_init_dmac(struct igb_adapter *adapter, u32 pba) wr32(E1000_DMCTXTH, 0); /* - * DMA Coalescing high water mark needs to be higher - * than the RX threshold. set hwm to PBA - 2 * max - * frame size + * DMA Coalescing high water mark needs to be greater + * than the Rx threshold. Set hwm to PBA - max frame + * size in 16B units, capping it at PBA - 6KB. */ - hwm = pba - (2 * adapter->max_frame_size); + hwm = 64 * pba - adapter->max_frame_size / 16; + if (hwm < 64 * (pba - 6)) + hwm = 64 * (pba - 6); + reg = rd32(E1000_FCRTC); + reg &= ~E1000_FCRTC_RTH_COAL_MASK; + reg |= ((hwm << E1000_FCRTC_RTH_COAL_SHIFT) + & E1000_FCRTC_RTH_COAL_MASK); + wr32(E1000_FCRTC, reg); + + /* + * Set the DMA Coalescing Rx threshold to PBA - 2 * max + * frame size, capping it at PBA - 10KB. + */ + dmac_thr = pba - adapter->max_frame_size / 512; + if (dmac_thr < pba - 10) + dmac_thr = pba - 10; reg = rd32(E1000_DMACR); reg &= ~E1000_DMACR_DMACTHR_MASK; - dmac_thr = pba - 4; - reg |= ((dmac_thr << E1000_DMACR_DMACTHR_SHIFT) & E1000_DMACR_DMACTHR_MASK); @@ -7085,7 +7098,6 @@ static void igb_init_dmac(struct igb_adapter *adapter, u32 pba) * coalescing(smart fifb)-UTRESH=0 */ wr32(E1000_DMCRTRH, 0); - wr32(E1000_FCRTC, hwm); reg = (IGB_DMCTLX_DCFLUSH_DIS | 0x4); -- 1.7.6.4 -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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