Re: [PATCH] e100: expose broadcast_disabled as a module option

Re: [PATCH] e100: expose broadcast_disabled as a module option

[Jeff Kirsher]

On Fri, Apr 23, 2010 at 13:14, Erwan Velu <erwanaliasr1@gmail.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@gmail.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...

-- 
Cheers,
Jeff

Re: [PATCH] e100: expose broadcast_disabled as a module option

[Stephen Hemminger]

On Fri, 23 Apr 2010 13:22:22 -0700
Jeff Kirsher <jeffrey.t.kirsher@intel.com> wrote:

> On Fri, Apr 23, 2010 at 13:14, Erwan Velu <erwanaliasr1@gmail.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@gmail.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?


-- 

Re: [PATCH] e100: expose broadcast_disabled as a module option

[Erwan Velu]

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@vyatta.com>:
> On Fri, 23 Apr 2010 13:22:22 -0700
> Jeff Kirsher <jeffrey.t.kirsher@intel.com> wrote:
>
>> On Fri, Apr 23, 2010 at 13:14, Erwan Velu <erwanaliasr1@gmail.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@gmail.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?
>
>
> --
>

Re: [PATCH] e100: expose broadcast_disabled as a module option

[Stephen Hemminger]

On Fri, 23 Apr 2010 23:03:59 +0200
Erwan Velu <erwanaliasr1@gmail.com> wrote:

> 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.

The point is that the driver can look at IFF_BROADCAST rather than having
module parameter. Module parameters are device driver specific and should
be avoid as much as possible in favor of general mechanism. This is a repeated
problem where users and vendors make special hooks that only work with their
driver, which makes life hard for other users and distribution providers.

Re: [PATCH] e100: expose broadcast_disabled as a module option

[Erwan Velu]

Agreed that will be a better implementation. Changes of IFF_BROADCAST
could play with this "broadcast_disabled" configuration switch to
increase the cpu efficiency.

 I'm not a kernel expert and I don't really figure how the changes of
the IFF_BROADCAST should be forwarded to the interfaces and how it can
be manipulated. I saw that ifconfig have a '-broadcast' option but
looks like none of my drivers are compatible with that.

Does any one you could help me understanding what should be the good way to
1- enabled/disabled IFF_BROADCAST for a given interface
2- populate this changes to the driver

Once I'll be able to have a proper patch using that, I'll post it
again to the list.

Cheers,
Erwan

2010/4/24 Stephen Hemminger <shemminger@vyatta.com>:
> On Fri, 23 Apr 2010 23:03:59 +0200
[...]
> The point is that the driver can look at IFF_BROADCAST rather than having
> module parameter. Module parameters are device driver specific and should
> be avoid as much as possible in favor of general mechanism. This is a repeated
> problem where users and vendors make special hooks that only work with their
> driver, which makes life hard for other users and distribution providers.
>

Re: [PATCH] e100: expose broadcast_disabled as a module option

[Erwan Velu]

2010/4/26 Erwan Velu <erwanaliasr1@gmail.com>:

After some research, here come my status :

> Does any one you could help me understanding what should be the good way to
> 1- enabled/disabled IFF_BROADCAST for a given interface

Looks like the current code isn't taking care of a possible changing
of IFF_BROADCAST. I can find some code in net/core/dev.c to handle
MULTICAST or PROMISC but nothing for BROADCAST.
do I have to implement one ?


> 2- populate this changes to the driver

Looks like I need then to add a .ndo_change_rx_flags function to
manage this changes.

Does someone confirm this is the way to go ?