275257 – net-libs/libpcap-1.0.1_pre20090616 utilizes too much kernel time

Bug 275257 - net-libs/libpcap-1.0.1_pre20090616 utilizes too much kernel time

Summary: net-libs/libpcap-1.0.1_pre20090616 utilizes too much kernel time

Status:	RESOLVED FIXED

Alias:	None

Product:	Gentoo Linux
Classification:	Unclassified
Component:	[OLD] Library (show other bugs)
Hardware:	AMD64 Linux

Importance:	High normal (vote)
Assignee:	Gentoo Netmon project

URL:
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Keywords:

Depends on:
Blocks:

Reported:	2009-06-24 09:02 UTC by Michael O'Brien
Modified:	2009-07-08 13:29 UTC (History)
CC List:	1 user (show)

See Also:
Package list:
Runtime testing required:	---

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Description Michael O'Brien 2009-06-24 09:02:00 UTC

Bug clearly visible when using a tool such as iftop. Uses near 100% of kernel CPU usage on any given CPU. Downgrade the library to version 1.0.0-r2 solve issue upon relaunch.

Reproducible: Always

Steps to Reproduce:
1. emerge -1 net-libs/libpcap-1.0.1_pre20090616 && emerge iftop
2. iftop
3. look at output of top or htop

Actual Results:  
iftop's CPU utilization will be ~97-98% kernel time when =net-libs/libpcap-1.0.1_pre20090616 is used

Expected Results:  
iftop CPU utilization would be ~1-2% user time when using a <=net-libs/libpcap-1.0.0-r2

Simply masking the affected version in /etc/portage/package.mask and emerge -NauD @system @world will solve the issue. Major issue on non-SMP systems or systems with strict cooling or resource requirements. Otherwise it's minor so I'm at a mix as how to report it.

Comment 1 Lars Wendler (Polynomial-C) (RETIRED) gentoo-dev

2009-06-24 09:37:55 UTC

I can confirm the reported problem with iftop.

Comment 2 Matt 2009-06-24 11:38:08 UTC

net-analyzer/snort and a bunch of other stuff seems to be affected too

here a list of some packages on my system that are dependent on net-libs/libpcap:

net-analyzer/iftop-0.17 (net-libs/libpcap)
net-analyzer/nmap-4.85_beta9 (net-libs/libpcap)
net-analyzer/snort-2.8.4.1 (virtual/libpcap)
net-dialup/ppp-2.4.4-r22 (activefilter ? >=virtual/libpcap-0.9.4)
net-misc/knock-0.5 (net-libs/libpcap)
net-wireless/wpa_supplicant-0.6.9 (!kernel_linux ? net-libs/libpcap)

re-compiling snort and iftop right now, hopefully this fixes the high cpu load (100%) of snort which I didn't have before the update ...

Comment 3 Michael O'Brien 2009-06-24 11:41:03 UTC

> re-compiling snort and iftop right now, hopefully this fixes the high cpu load
> (100%) of snort which I didn't have before the update ...

At least for me I found I only needed to recompile the library, but that might be determined on a per-package basis

Comment 4 Matt 2009-06-24 12:20:05 UTC

I did recompile both libpcap and snort, iftop,

after a reboot (after the recompile it still produced that high cpu load, it most probably was still in memory due to its dependency of wpa_supplicant) snort isn't consuming that much anymore

success !

Thanks for reporting, Michael :)

Comment 5 Peter Volkov (RETIRED) gentoo-dev

2009-07-08 13:29:46 UTC

Thank you for report Michael. Fixed in libpcap-1.0.1_pre20090708.