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Date:      Thu, 16 Jun 2005 01:18:23 +0200
From:      Jeremie Le Hen <jeremie@le-hen.org>
To:        freebsd-current@FreeBSD.org
Subject:   incorrect ping(8) interval with powerd(8)
Message-ID:  <20050615231823.GB2239@obiwan.tataz.chchile.org>

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Hi list,

as the subjects state, when powerd(8) is running and has set a lower
frequency than the processor's natural one, interval between each
packets are too long.  When my laptop is plugged, I told powerd(8) to
run the processor at maximum speed (-a max).

Let's have a look at this :
%%%
    jarjarbinks:root# sysctl hw.acpi.acline
    hw.acpi.acline: 1
    jarjarbinks:root# sysctl dev.cpu.0.freq
    dev.cpu.0.freq: 1735
    jarjarbinks:root# time ping -qc 2 192.168.1.1
    PING 192.168.1.1 (192.168.1.1): 56 data bytes
    
    --- 192.168.1.1 ping statistics ---
    2 packets transmitted, 2 packets received, 0% packet loss
    round-trip min/avg/max/stddev = 0.266/0.269/0.271/0.002 ms
    
    real    0m1.003s
    user    0m0.001s
    sys     0m0.001s

    jarjarbinks:root# sysctl hw.acpi.acline
    hw.acpi.acline: 0
    jarjarbinks:root# sysctl dev.cpu.0.freq
    dev.cpu.0.freq: 216
    jarjarbinks:root# time ping -qc 2 192.168.1.1
    PING 192.168.1.1 (192.168.1.1): 56 data bytes
    
    --- 192.168.1.1 ping statistics ---
    2 packets transmitted, 2 packets received, 0% packet loss
    round-trip min/avg/max/stddev = 0.637/0.814/0.991/0.177 ms
    
    real    0m2.252s
    user    0m0.004s
    sys     0m0.021s
%%%

I check ping(8) source code and it appears it uses select(8) to wait
the desired amount of time.  I don't think this is the intended
behaviour.  Where does this bug (feature?) come from ?

Regards,
-- 
Jeremie Le Hen
< jeremie at le-hen dot org >< ttz at chchile dot org >



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