netdev - Re: [net-next] stmmac: limit max_mtu in case of 4KiB and use __netdev_alloc

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Date:	Tue, 18 Oct 2011 14:26:10 +0200
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Giuseppe CAVALLARO <peppe.cavallaro@...com>
Cc:	netdev@...r.kernel.org, davem@...emloft.net
Subject: Re: [net-next] stmmac: limit max_mtu in case of 4KiB and use
 __netdev_alloc_skb (V2)

Le mardi 18 octobre 2011 à 13:39 +0200, Giuseppe CAVALLARO a écrit :
> Problem using big mtu around 4096 bytes is you end allocating (4096
> +NET_SKB_PAD + NET_IP_ALIGN + sizeof(struct skb_shared_info) bytes ->
> 8192 bytes : order-1 pages
> 
> It's better to limit the mtu to SKB_MAX_HEAD(NET_SKB_PAD),
> to have no more than one page per skb.
> 
> Also the patch changes the netdev_alloc_skb_ip_align() done in
> init_dma_desc_rings() and uses a variant allowing GFP_KERNEL allocations
> allowing the driver to load even in case of memory pressure.
> 
> Reported-by: Eric Dumazet <eric.dumazet@...il.com>
> Signed-off-by: Giuseppe Cavallaro <peppe.cavallaro@...com>
> ---
>  drivers/net/ethernet/stmicro/stmmac/stmmac_main.c |    6 ++++--
>  1 files changed, 4 insertions(+), 2 deletions(-)
> 

Seems good, thanks :)

Signed-off-by: Eric Dumazet <eric.dumazet@...il.com>


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