On Sat, 07 Nov 2020 14:00:04 +0100 Thomas Rosenstein via Bloat <[email protected]> wrote: > Here's an extract from the ethtool https://pastebin.com/cabpWGFz just in > case there's something hidden.
Yes, there is something hiding in the data from ethtool_stats.pl[1]: (10G Mellanox Connect-X cards via 10G SPF+ DAC) stat: 1 ( 1) <= outbound_pci_stalled_wr_events /sec stat: 339731557 (339,731,557) <= rx_buffer_passed_thres_phy /sec I've not seen this counter 'rx_buffer_passed_thres_phy' before, looking in the kernel driver code it is related to "rx_buffer_almost_full". The numbers per second is excessive (but it be related to a driver bug as it ends up reading "high" -> rx_buffer_almost_full_high in the extended counters). stat: 29583661 ( 29,583,661) <= rx_bytes /sec stat: 30343677 ( 30,343,677) <= rx_bytes_phy /sec You are receiving with 236 Mbit/s in 10Gbit/s link. There is a difference between what the OS sees (rx_bytes) and what the NIC hardware sees (rx_bytes_phy) (diff approx 6Mbit/s). stat: 19552 ( 19,552) <= rx_packets /sec stat: 19950 ( 19,950) <= rx_packets_phy /sec Above RX packet counters also indicated HW is seeing more packets that OS is receiving. Next counters is likely your problem: stat: 718 ( 718) <= tx_global_pause /sec stat: 954035 ( 954,035) <= tx_global_pause_duration /sec stat: 714 ( 714) <= tx_pause_ctrl_phy /sec It looks like you have enabled Ethernet Flow-Control, and something is causing pause frames to be generated. It seem strange that this happen on a 10Gbit/s link with only 236 Mbit/s. The TX byte counters are also very strange: stat: 26063 ( 26,063) <= tx_bytes /sec stat: 71950 ( 71,950) <= tx_bytes_phy /sec -- Best regards, Jesper Dangaard Brouer MSc.CS, Principal Kernel Engineer at Red Hat LinkedIn: http://www.linkedin.com/in/brouer [1] https://github.com/netoptimizer/network-testing/blob/master/bin/ethtool_stats.pl Strange size distribution: stat: 19922 ( 19,922) <= rx_1519_to_2047_bytes_phy /sec stat: 14 ( 14) <= rx_65_to_127_bytes_phy /sec _______________________________________________ Bloat mailing list [email protected] https://lists.bufferbloat.net/listinfo/bloat
