netdev - Interaction between GSO and TSQ for single TCP stream

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Date:	Tue, 27 Jan 2015 11:57:29 -0800
From:	Tom Herbert <therbert@...gle.com>
To:	Eric Dumazet <edumazet@...gle.com>
Cc:	Linux Netdev List <netdev@...r.kernel.org>
Subject: Interaction between GSO and TSQ for single TCP stream

Eric,

I am looking at why we are unable to achieve line rate throughput with
a single connection using UDP encapsulation that supports GSO/GRO. I
discovered that even for a non-encpasulated TCP connection I'm not
able to get line rate using GSO/GRO (but do with TSO/LRO). There seems
to be some interaction between TSQ and GSO. Setting
tcp_limit_output_bytes to 1000000 gets single connection up to line
rate for both native and encapsulated TCP.

Some data:

- netperf TCP_STREAM for a single connection no encapsulation
  Using TSO/LRO
    9412.44 Gbps
  Using GSO/GRO (ethtool -K eth0 gso on gro on tso off lro off)
    9286.08 Gbps
  Using GSO/GRO with larger limit (echo 1000000 >
/proc/sys/net/ipv4/tcp_limit_output_bytes)
    9412.75

- netperf TCP_STREAM for a single connection for GUE-IPIP encapsulation with RCO
  Using GSO/GRO
    8842.89 Gbps
  Using GSO/GRO with larger limit (echo 1000000 >
/proc/sys/net/ipv4/tcp_limit_output_bytes)
    9143.99 Gbps

Any ideas on how to address this?

Thanks,
Tom
--
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