netdev - Re: [PATCH net-next v6 2/3] udp: implement memory accounting helpers

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Date:   Fri, 21 Oct 2016 14:13:43 -0700
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     Paolo Abeni <pabeni@...hat.com>
Cc:     netdev@...r.kernel.org, "David S. Miller" <davem@...emloft.net>,
        James Morris <jmorris@...ei.org>,
        Trond Myklebust <trond.myklebust@...marydata.com>,
        Alexander Duyck <aduyck@...antis.com>,
        Daniel Borkmann <daniel@...earbox.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Tom Herbert <tom@...bertland.com>,
        Hannes Frederic Sowa <hannes@...essinduktion.org>,
        Edward Cree <ecree@...arflare.com>, linux-nfs@...r.kernel.org
Subject: Re: [PATCH net-next v6 2/3] udp: implement memory accounting helpers

On Fri, 2016-10-21 at 13:55 +0200, Paolo Abeni wrote:
> Avoid using the generic helpers.
> Use the receive queue spin lock to protect the memory
> accounting operation, both on enqueue and on dequeue.
> 
> On dequeue perform partial memory reclaiming, trying to
> leave a quantum of forward allocated memory.
> 
> On enqueue use a custom helper, to allow some optimizations:
> - use a plain spin_lock() variant instead of the slightly
>   costly spin_lock_irqsave(),
> - avoid dst_force check, since the calling code has already
>   dropped the skb dst
> - avoid orphaning the skb, since skb_steal_sock() already did
>   the work for us
> 
> The above needs custom memory reclaiming on shutdown, provided
> by the udp_destruct_sock().

Acked-by: Eric Dumazet <edumazet@...gle.com>