netdev - Re: VLAN GARP triggers a lot of timers if linux compiled with VLAN_8021Q

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Date:	Wed, 29 Sep 2010 13:02:02 +0200
From:	didier <did447@...il.com>
To:	Patrick McHardy <kaber@...sh.net>
Cc:	netdev@...r.kernel.org
Subject: Re: VLAN GARP triggers a lot of timers if linux compiled with VLAN_8021Q_GVRP

Hi,
>
>> garp_join_timer_arm()
>>
>> delay = (u64)msecs_to_jiffies(garp_join_time)* net_random() >> 32;
>> mod_timer(&app->join_timer, jiffies +delay)
>>
>> Isn't this stuff triggering a *lot* of events?
>
> Yeah, something around 5-10 timers per second IIRC. There was an RFC
> patch a while ago to only schedule the timer on-demand, I'll see
> whether I can find it again.

But with this formula delay can be often rather small, or do I miss something?

Here on an idle box with two vlans vmstat output shows  burst of up to
15000 context switches per seconds.

Didier
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