netdev - Re: [PATCH net-next] mlx4: exploit skb->xmit_more to conditionally send doorbell

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Date:	Thu, 25 Sep 2014 13:47:26 -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>, Amir Vadai <amirv@...lanox.com>,
	John Fastabend <john.r.fastabend@...el.com>
Subject: Re: [PATCH net-next] mlx4: exploit skb->xmit_more to conditionally
 send doorbell

On Thu, 2014-09-25 at 08:36 -0700, Eric Dumazet wrote:

> After patch :
> 
>     32.78%  [kernel]  [k] __copy_skb_header             
>      8.26%  [kernel]  [k] mlx4_en_xmit                  
>      7.25%  [kernel]  [k] __alloc_skb                   
>      7.18%  [kernel]  [k] copy_user_enhanced_fast_string
>      4.39%  [kernel]  [k] skb_segment                   
>      2.87%  [kernel]  [k] memcpy                        
>      2.59%  [kernel]  [k] tcp_sendmsg                   
>      2.50%  [kernel]  [k] _raw_spin_lock                
>      2.38%  [kernel]  [k] dev_hard_start_xmit           
>      1.52%  [kernel]  [k] tcp_gso_segment               
>      1.50%  [kernel]  [k] kmem_cache_alloc_node_trace   
>      1.40%  [kernel]  [k] kmem_cache_alloc_node         
>      1.16%  [kernel]  [k] ip_send_check                 
> 

After __copy_skb_header() optimization I get something even nicer ;)

    19.90%  [kernel]          [k] __copy_skb_header             
    15.16%  [kernel]          [k] skb_segment                   
     7.02%  [kernel]          [k] __alloc_skb                   
     6.89%  [kernel]          [k] copy_user_enhanced_fast_string
     6.60%  [kernel]          [k] mlx4_en_xmit                  
     2.70%  [kernel]          [k] _raw_spin_lock                
     2.68%  [kernel]          [k] memcpy                        
     2.41%  [kernel]          [k] tcp_sendmsg                   

I'll post this patch asap.


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