netdev - Re: [PATCH net-next] fq_codel: add batch ability to fq_codel

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Message-ID: <1462199668.5535.239.camel@edumazet-glaptop3.roam.corp.google.com>
Date:	Mon, 02 May 2016 07:34:28 -0700
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Jesper Dangaard Brouer <brouer@...hat.com>
Cc:	David Miller <davem@...emloft.net>,
	netdev <netdev@...r.kernel.org>, Dave Taht <dave.taht@...il.com>,
	Jonathan Morton <chromatix99@...il.com>
Subject: Re: [PATCH net-next] fq_codel: add batch ability to fq_codel_drop()

On Mon, 2016-05-02 at 09:49 +0200, Jesper Dangaard Brouer wrote:

> What about using bulk free of SKBs here?
> 
> There is a very high probability that we are hitting SLUB slowpath,
> which involves an expensive locked cmpxchg_double per packet.  Instead
> we can amortize this cost via kmem_cache_free_bulk().
> 
> Maybe extend kfree_skb_list() to hide the slab/kmem_cache call?

Sounds tricky, because of skb destructors. skb are complex objects.

For each skb, need to free the frags, skb->head, and skb.