netdev - Re: [PATCH] bonding:avoid repeated display of same link status change

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Message-ID: <20181023163825.GB22291@unicorn.suse.cz>
Date:   Tue, 23 Oct 2018 18:38:25 +0200
From:   Michal Kubecek <mkubecek@...e.cz>
To:     Eric Dumazet <eric.dumazet@...il.com>
Cc:     Mahesh Bandewar
         (महेश बंडेवार) <maheshb@...gle.com>, mk.singh@...cle.com,
        linux-netdev <netdev@...r.kernel.org>,
        Jay Vosburgh <j.vosburgh@...il.com>,
        Veaceslav Falico <vfalico@...il.com>,
        Andy Gospodarek <andy@...yhouse.net>,
        "David S. Miller" <davem@...emloft.net>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] bonding:avoid repeated display of same link status change

On Tue, Oct 23, 2018 at 06:26:14PM +0200, Michal Kubecek wrote:
> On Tue, Oct 23, 2018 at 09:10:44AM -0700, Eric Dumazet wrote:
> > 
> > 
> > On 10/23/2018 08:54 AM, Mahesh Bandewar (महेश बंडेवार) wrote:
> > 
> > > Atomic operations are expensive (on certain architectures) and miimon
> > > runs quite frequently. Is the added cost of these atomic operations
> > > even worth just to avoid *duplicate info* messages? This seems like a
> > > overkill!
> > 
> > atomic_read() is a simple read, no atomic operation involved.
> > 
> > Same remark for atomic_set()
> 
> Which makes me wonder if the patch really needs atomic_t.

IMHO it does not. AFAICS multiple instances of bond_mii_monitor() cannot
run simultaneously for the same bond so that there doesn't seem to be
anything to collide with. (And if they could, we would need to test and
set the flag atomically in bond_miimon_inspect().)

Michal Kubecek