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Subject: Re: [PATCH] phonet: Check input from user before allocating
From: Eric Dumazet <eric.dumazet@gmail.com>
To: David Miller <davem@davemloft.net>
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Date: Tue, 03 Apr 2012 04:15:04 +0200
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On Mon, 2012-04-02 at 21:59 -0400, David Miller wrote:
> From: Eric Dumazet <eric.dumazet@gmail.com>
> Date: Tue, 03 Apr 2012 03:53:17 +0200
> 
> > Not that AF_UNIX does nothing in this respect, it can use order-XX pages
> > for large datagrams.
> > 
> > (I beleve I sent a patch some time ago to address this point)
> 
> Yes, on the datagram side it's a problem.
> 
> For stream AF_UNIX sockets the allocation is capped at SKB_MAX_ALLOC
> which evaluates to an order 2 page.
> 
> Overall, AF_UNIX ought to be easy to deal with since all of the
> routines that copy data between userspace and SKBs can handle
> segmented SKBs and thus most of the work is converting over to
> sock_alloc_send_pskb() and setting data_len how we set the normal
> length of sock_alloc_skb_skb() currently.
> 
> Anyways, feel free to resubmit your patch.

This was indeed a basic patch, but it probably can lower raw performance
on some apps, (if memory frag is not an issue) so I need to bench it. 


Any idea of a representative benchmark in dgram af_unix ?

http://patchwork.ozlabs.org/patch/114103/

I'll respin it with proper performance resuts.