running tcpdump seems to block disk operations on loaded systems

[Nikola Ciprich <nikola.ciprich () linuxbox cz>]

Hello,

I'd like to ask about following problem we've hit few times..
When starting tcpdump (using either -i any or -i xxx) on system with
higher disk load, it sometimes happens that system seems to hang almost immediately and 
loadavg value shoots to  really bad numbers (almost 200 for example). Before starting it, 
system is quite loaded, but  not that badly (loadavg is like 1-4). Network load is also not that bad..
we're using tcpdump-4.1.1, libpcap-4.1.1 and various kernels (usually latest
x86_64 2.6.32.x).
Is there anything I should check, or any hint on how could I find the reason of this
problem?

I'll be gratefull for any answers I could get

thanks in advance

nik


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