Re: linux-next network throughput performance regression
From: Eric Dumazet <hidden>
Date: 2015-11-07 19:50:37
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On Sat, 2015-11-07 at 11:35 -0800, Eric Dumazet wrote:
On Fri, 2015-11-06 at 14:30 -0700, David Ahern wrote:quoted
On 11/6/15 2:18 PM, Simon Xiao wrote:quoted
The .config file used to build linux-next kernel is attached to this mail.Thanks. Failed to notice this on the first response; my brain filled in. Why linux-next tree? Can you try net-next which is more relevant for this mailing list, post the top commit id and config file used?Throughput on a single TCP flow for a 40G NIC can be tricky to tune. Make sure IRQ are properly setup/balanced, as I know that IRQ names were changed recently and your scripts might have not noticed... Also "ethtool -c eth0" might show very different interrupt coalescing params ? I too have a Mellanox 40Gb in my lab and saw no difference in performance with recent kernels. Of course, a simple "perf record -a -g sleep 4 ; perf report" might point to some obvious issue. Like unexpected segmentation in case of forwarding...
I did a test with current net tree on both sender and receiver lpaa23:~# ./netperf -H 10.246.7.152 MIGRATED TCP STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to 10.246.7.152 () port 0 AF_INET Recv Send Send Socket Socket Message Elapsed Size Size Size Time Throughput bytes bytes bytes secs. 10^6bits/sec 87380 16384 16384 10.00 26864.98 lpaa23:~# ethtool -c eth1 Coalesce parameters for eth1: Adaptive RX: on TX: off stats-block-usecs: 0 sample-interval: 0 pkt-rate-low: 400000 pkt-rate-high: 450000 rx-usecs: 16 rx-frames: 44 rx-usecs-irq: 0 rx-frames-irq: 0 tx-usecs: 16 tx-frames: 16 tx-usecs-irq: 0 tx-frames-irq: 256 rx-usecs-low: 0 rx-frame-low: 0 tx-usecs-low: 0 tx-frame-low: 0 rx-usecs-high: 128 rx-frame-high: 0 tx-usecs-high: 0 tx-frame-high: 0 lpaa23:~# ethtool -C eth1 tx-usecs 4 tx-frames 4 lpaa23:~# ./netperf -H 10.246.7.152 MIGRATED TCP STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to 10.246.7.152 () port 0 AF_INET Recv Send Send Socket Socket Message Elapsed Size Size Size Time Throughput bytes bytes bytes secs. 10^6bits/sec 87380 16384 16384 10.00 30206.27