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16b61beb39
Currently the high and low water marks for PFC are being set conservatively for jumbo frames. This means the RX buffers are being underutilized in the default 1500 MTU. This patch fixes this so that the water marks are set as described in the data sheet considering the MTU size. The equation used is, RTT * 1.44 + MTU * 1.44 + MTU Where RTT is the round trip time and MTU is the max frame size in KB. To avoid floating point arithmetic FC_HIGH_WATER is defined ((((RTT + MTU) * 144) + 99) / 100) + MTU This changes how the hardware field fc.low_water and fc.high_water are used. With this change they are no longer storing the actual low water and high water markers but are storing the required head room in the buffer. This simplifies the logic and we do not need to account for the size of the buffer when setting the thresholds. Testing with iperf and 16 threads showed a slight uptick in throughput over a single traffic class .1-.2Gbps and a reduction in pause frames. Without the patch a 30 second run would show ~10-15 pause frames being transmitted with the patch ~2-5 are seen. Test were run back to back with 82599. Note RXPBSIZE is in KB and low and high water marks fields are also in KB. However the FCRT* registers are 32B granularity and right shifted 5 into the register, (((rx_pbsize - water_mark) * 1024) / 32) << 5 is the most explicit conversion here we simplify (rx_pbsize - water_mark) * 32 << 5 = (rx_pbsize - water_mark) << 10 This patch updates the PFC thresholds and legacy FC thresholds. Signed-off-by: John Fastabend <john.r.fastabend@intel.com> Tested-by: Ross Brattain <ross.b.brattain@intel.com> Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com> |
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| .. | ||
| ixgbe_82598.c | ||
| ixgbe_82599.c | ||
| ixgbe_common.c | ||
| ixgbe_common.h | ||
| ixgbe_dcb_82598.c | ||
| ixgbe_dcb_82598.h | ||
| ixgbe_dcb_82599.c | ||
| ixgbe_dcb_82599.h | ||
| ixgbe_dcb_nl.c | ||
| ixgbe_dcb.c | ||
| ixgbe_dcb.h | ||
| ixgbe_ethtool.c | ||
| ixgbe_fcoe.c | ||
| ixgbe_fcoe.h | ||
| ixgbe_main.c | ||
| ixgbe_mbx.c | ||
| ixgbe_mbx.h | ||
| ixgbe_phy.c | ||
| ixgbe_phy.h | ||
| ixgbe_sriov.c | ||
| ixgbe_sriov.h | ||
| ixgbe_type.h | ||
| ixgbe.h | ||
| Makefile | ||