high ksoftirqd while using module gtp?

Tony Clark chiefy.padua at gmail.com
Wed Jun 19 12:07:13 UTC 2019


Dear All,

I've been using the GTP-U kernel module to communicate with a P-GW.

Running Fedora 29, kernel 4.18.16-300.fc29.x86_64.

At high traffic levels through the GTP-U tunnel I see the performance
degrade as 100% CPU is consumed by a single ksoftirqd process.

It is running on a multi-cpu machine and as far as I can tell the load is
evenly spread across the cpus (ie either manually via smp_affinity, or even
irqbalance, checking /proc/interrupts so forth.).

Has anyone else experienced this?

Is there any particular area you could recommend I investigate to find the
root cause of this bottleneck, as i'm starting to scratch my head where to
look next...

Thanks in advance
Tony

---- FYI

modinfo gtp
filename:
/lib/modules/4.18.16-300.fc29.x86_64/kernel/drivers/net/gtp.ko.xz
alias:          net-pf-16-proto-16-family-gtp
alias:          rtnl-link-gtp
description:    Interface driver for GTP encapsulated traffic
author:         Harald Welte <hwelte at sysmocom.de>
license:        GPL
depends:        udp_tunnel
retpoline:      Y
intree:         Y
name:           gtp
vermagic:       4.18.16-300.fc29.x86_64 SMP mod_unload

modinfo udp_tunnel
filename:
/lib/modules/4.18.16-300.fc29.x86_64/kernel/net/ipv4/udp_tunnel.ko.xz
license:        GPL
depends:
retpoline:      Y
intree:         Y
name:           udp_tunnel
vermagic:       4.18.16-300.fc29.x86_64 SMP mod_unload
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