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List:       busybox
Subject:    Re: udhcpc: don't use BPF filter, users report problems (bugs 4598, 6746), commit e4785ca653d0e21992
From:       Denys Vlasenko <vda.linux () googlemail ! com>
Date:       2014-02-05 14:10:02
Message-ID: CAK1hOcOP3gL2X-pMwrHsH3n2BpnAR6iCARBJTgXxy9Ab8s2H6g () mail ! gmail ! com
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On Tue, Feb 4, 2014 at 8:48 PM, Cristian Ionescu-Idbohrn
<cristian.ionescu-idbohrn@axis.com> wrote:
> The backside of this, IIRC, is that udhcpc will eat up huge chunks of
> CPU parsing "uninteresting" packets, on "heavy" loaded networks.

udhcpc does not listen to the network after it established a lease.
It just sleeps, usually for hours, waiting for 1/2 of the lease time
to expire. No network sockets are open during that time:

# ls -l /proc/1412/fd
total 0
lr-x------ 1 root root 64 Feb  5 15:08 0 -> /dev/null
l-wx------ 1 root root 64 Feb  5 15:08 1 -> pipe:[16588]
l-wx------ 1 root root 64 Feb  5 15:08 2 -> pipe:[16588]
lr-x------ 1 root root 64 Feb  5 15:08 3 -> pipe:[22350]
l-wx------ 1 root root 64 Feb  5 15:08 4 -> pipe:[22350]

fds 1 and 2 are stdout/err (in my case, directed to a logger),
fds 3 and 4 is the internal signal pipe.
-- 
vda
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