linux-kernel - Re: [PATCH] e100: expose broadcast

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Message-ID: <r2ob43bf5491004231403o64f8b88bsa9543d9910648d97@mail.gmail.com>
Date:	Fri, 23 Apr 2010 23:03:59 +0200
From:	Erwan Velu <erwanaliasr1@...il.com>
To:	Stephen Hemminger <shemminger@...tta.com>
Cc:	Jeff Kirsher <jeffrey.t.kirsher@...el.com>,
	netdev <netdev@...r.kernel.org>,
	David Miller <davem@...emloft.net>,
	linux-kernel@...r.kernel.org, jesse.brandeburg@...el.com,
	bruce.w.allan@...el.com, alexander.h.duyck@...el.com,
	peter.p.waskiewicz.jr@...el.com, john.ronciak@...el.com
Subject: Re: [PATCH] e100: expose broadcast_disabled as a module option

I first tried "ifconfig -broadcast" without any success, so I forced
the driver to unset IFF_BROADCAST, the interface didn't showed anymore
the BROADCAST option with ifconfig. But I didn't noticed any reduction
in the amount of context/switches on my host.

I found the broadcast_disabled far more efficient when considering the
cpu impact.


2010/4/23 Stephen Hemminger <shemminger@...tta.com>:
> On Fri, 23 Apr 2010 13:22:22 -0700
> Jeff Kirsher <jeffrey.t.kirsher@...el.com> wrote:
>
>> On Fri, Apr 23, 2010 at 13:14, Erwan Velu <erwanaliasr1@...il.com> wrote:
>> > Hi folks,
>> >
>> > I've been facing a very noisy network where hundreds broadcast packets
>> > were generated every second.
>> > When this traffic can't be controlled at the source, there is a side
>> > effect on some systems.
>> > I was having some idle systems that will never be targeted by this
>> > broadcast traffic that got loaded just by receiving that "flood".
>> > I mean by loaded that this light hardware was generating 300
>> > context/switches per second.
>> >
>> > I was looking for many options to avoid this traffic to disturb this
>> > hosts and I discovered that the e100 driver was featuring a
>> > "broadcast_disabled" configure option.
>> > I realize that this option is not controllable, so I wrote this simple
>> > patch that expose this option as a module option.
>> > This allow me to tell this hosts not to listen anymore this traffic.
>> >
>> > The result is clearly good as my systems are now running at 21
>> > context/switches while being idle.
>> > Hope this patch isn't too bad and could help others that faces the same problem.
>> >
>> > Patch can be downloaded here :
>> > http://konilope.linuxeries.org/e100_broadcast_disabled.patch
>> >
>> > Even if gmail is eating the inlined, patch, at least that make it
>> > easier to read it for humans.
>> > If the patch is acked, the downloaded one will be more clean ;)
>> >
>> > This patch was generated on top of the latest 2.6 torvald's git.
>> > Cheers,
>> > Erwan
>> >
>> > Signed-off-by: Erwan Velu <erwanaliasr1@...il.com>
>> >
>> > diff --git a/drivers/net/e100.c b/drivers/net/e100.c
>> > index b997e57..2ba582f 100644
>> > --- a/drivers/net/e100.c
>> > +++ b/drivers/net/e100.c
>> > @@ -194,12 +194,15 @@ MODULE_FIRMWARE(FIRMWARE_D102E);
>> >  static int debug = 3;
>> >  static int eeprom_bad_csum_allow = 0;
>> >  static int use_io = 0;
>> > +static int broadcast_disabled = 0;
>> >  module_param(debug, int, 0);
>> >  module_param(eeprom_bad_csum_allow, int, 0);
>> >  module_param(use_io, int, 0);
>> > +module_param(broadcast_disabled, int, 0);
>> >  MODULE_PARM_DESC(debug, "Debug level (0=none,...,16=all)");
>> >  MODULE_PARM_DESC(eeprom_bad_csum_allow, "Allow bad eeprom checksums");
>> >  MODULE_PARM_DESC(use_io, "Force use of i/o access mode");
>> > +MODULE_PARM_DESC(broadcast_disabled, "Filter broadcast packets
>> > (0=disabled (default), 1=enabled)");
>> >  #define DPRINTK(nlevel, klevel, fmt, args...) \
>> >        (void)((NETIF_MSG_##nlevel & nic->msg_enable) && \
>> >        printk(KERN_##klevel PFX "%s: %s: " fmt, nic->netdev->name, \
>> > @@ -1131,6 +1134,8 @@ static void e100_configure(struct nic *nic,
>> > struct cb *cb, struct sk_buff *skb)
>> >                config->promiscuous_mode = 0x1;         /* 1=on, 0=off */
>> >        }
>> >
>> > +       config->broadcast_disabled = broadcast_disabled; /* Broadcast filtering */
>> > +
>> >        if (nic->flags & multicast_all)
>> >                config->multicast_all = 0x1;            /* 1=accept, 0=no */
>> > --
>>
>> Adding Netdev...
>>
>
> What is wrong with using existing IFF_BROADCAST flag?
>
>
> --
>
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