netdev - Re: [PATCH RFC net-next 4/4] bridge: add ability to turn off fdb used updates

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Date:   Thu, 02 Feb 2017 21:47:37 -0500 (EST)
From:   David Miller <davem@...emloft.net>
To:     nikolay@...ulusnetworks.com
Cc:     netdev@...r.kernel.org, roopa@...ulusnetworks.com,
        stephen@...workplumber.org
Subject: Re: [PATCH RFC net-next 4/4] bridge: add ability to turn off fdb
 used updates

From: Nikolay Aleksandrov <nikolay@...ulusnetworks.com>
Date: Tue, 31 Jan 2017 16:31:58 +0100

> @@ -197,7 +197,8 @@ int br_handle_frame_finish(struct net *net, struct sock *sk, struct sk_buff *skb
>  		if (dst->is_local)
>  			return br_pass_frame_up(skb);
>  
> -		dst->used = jiffies;
> +		if (br->used_enabled)
> +			dst->used = jiffies;

Have you tried:

	if (dst->used != jiffies)
		dst->used = jiffies;

If that isn't effective, you can tweak the test to decrease the
granularity of the value.  Basically, if dst->used is within
1 HZ of jiffies, don't do the write.

I suspect this might help a lot, and not require a new bridging
option.