netdev - Re: [PATCH v6] net: batch skb dequeueing from softnet input_pkt

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Date:	Sun, 02 May 2010 16:27:28 +0200
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Arjan van de Ven <arjan@...radead.org>
Cc:	Andi Kleen <andi@...stfloor.org>,
	David Miller <davem@...emloft.net>, hadi@...erus.ca,
	xiaosuo@...il.com, therbert@...gle.com, shemminger@...tta.com,
	netdev@...r.kernel.org, lenb@...nel.org
Subject: Re: [PATCH v6] net: batch skb dequeueing from softnet
 input_pkt_queue

Le dimanche 02 mai 2010 à 07:13 -0700, Arjan van de Ven a écrit :
> > 
> > Cn                Avg residency       P-states (frequencies)
> > C0 (cpu running)        (68.9%)         2.93 Ghz    46.5%
> > polling           0.0ms ( 0.0%)         2.80 Ghz     5.1%
> > C1 mwait          0.0ms ( 0.0%)         2.53 Ghz     3.0%
> > C2 mwait          0.0ms (31.1%)         2.13 Ghz     2.8%
> >                                         1.60 Ghz    38.2%
> 
> I bet your system advertizes C2 with the same latency as C1,
> but with lower power... which means Linux will pretty much never
> pick C1.... no matter how much you take Andi's patch.
> 
> this is a bios thing... and until we put in the patch to override the
> bios values (I can dust it off but it might need a bit of tweaking
> since it was against .31) Andi's patch alone won't cut it... you also
> need a non-lying bios ;)
> 
> 
> 
# pwd
/sys/devices/system/cpu/cpu15/cpuidle
# grep . */*
state0/desc:CPUIDLE CORE POLL IDLE
state0/latency:0
state0/name:C0
state0/power:4294967295
state0/time:0
state0/usage:0
state1/desc:ACPI FFH INTEL MWAIT 0x0
state1/latency:1
state1/name:C1
state1/power:1000
state1/time:433855186
state1/usage:126869
state2/desc:ACPI FFH INTEL MWAIT 0x10
state2/latency:64
state2/name:C2
state2/power:500
state2/time:198095020416
state2/usage:76287744

C2 latency seems to be 64  (us ?), while C1 seems to be 1

BIOS Information
	Vendor: HP
	Version: I24
	Release Date: 10/01/2009

# powertop
PowerTOP 1.11   (C) 2007, 2008 Intel Corporation 

Collecting data for 5 seconds 


Your CPU supports the following C-states : C1 C2 C3 
Your BIOS reports the following C-states : C1 C2 

C3 seems to be disabled in BIOS


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