Bug 232451 - [igb] I210 NIC can not send more than ~670Mbit/s with flow control enabled.
Summary: [igb] I210 NIC can not send more than ~670Mbit/s with flow control enabled.
Status: New
Alias: None
Product: Base System
Classification: Unclassified
Component: kern (show other bugs)
Version: 11.2-STABLE
Hardware: amd64 Any
: --- Affects Only Me
Assignee: freebsd-net mailing list
URL:
Keywords: IntelNetworking
Depends on:
Blocks:
 
Reported: 2018-10-19 17:12 UTC by Lev A. Serebryakov
Modified: 2018-11-06 21:48 UTC (History)
2 users (show)

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Description Lev A. Serebryakov freebsd_committer 2018-10-19 17:12:16 UTC
I have server which is equipped with I210 NIC and has 11.2-STABLE installed.

With default config and MTU 9000 this server can not send faster than ~670Mbit/s on network without any other load (tested with iperf3).

If I set "sysctl dev.igb.0.fc" to 0, it easily sends 990-995Mbit/s at same network to same client.

Other problem is, that after mtu change with "ifconfig igb mtu ..." speed drops again, but "sysctl dev.igb.0.fc" is 0 still. To turn off flow control again it is needed to flip "sysctl dev.igb.0.fc" to non-zero and to zero again.