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From: Eric Dumazet <eric.dumazet@gmail.com>
To: David Miller <davem@davemloft.net>, saeedm@mellanox.com
Cc: netdev@vger.kernel.org
Subject: Re: [RFC net-next 1/2] net: net-porcfs: Reduce rcu lock critical section
Date: Tue, 10 Apr 2018 13:35:22 -0700	[thread overview]
Message-ID: <75137dbf-4608-127e-1601-10a3c13e3a32@gmail.com> (raw)
In-Reply-To: <20180410.131649.583776764903333305.davem@davemloft.net>



On 04/10/2018 10:16 AM, David Miller wrote:
> 
> The tradeoff here is that now you are doing two unnecessary atomic
> operations per stats dump.
> 
> That is what the RCU lock allows us to avoid.
> 

dev_hold() and dev_put() are actually per cpu increment and decrements,
pretty cheap these days.

Problem here is that any preemption of the process holding device reference
might trigger warnings in device unregister.

  reply	other threads:[~2018-04-10 20:35 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-10 17:08 [RFC net-next 1/2] net: net-porcfs: Reduce rcu lock critical section Saeed Mahameed
2018-04-10 17:08 ` [RFC net-next 2/2] net: net-sysfs: Reduce netstat_show read_lock " Saeed Mahameed
2018-04-10 17:17   ` David Miller
2018-04-10 17:16 ` [RFC net-next 1/2] net: net-porcfs: Reduce rcu lock " David Miller
2018-04-10 20:35   ` Eric Dumazet [this message]
2018-04-11 18:59     ` Saeed Mahameed
2018-04-11 22:30       ` Eric Dumazet
2018-04-11 23:47         ` Saeed Mahameed
2018-04-12  2:59           ` Eric Dumazet
2018-04-12 19:12             ` Saeed Mahameed
2018-04-16 20:50               ` Saeed Mahameed
2018-04-16 21:07                 ` Eric Dumazet

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