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Date: Mon, 17 Feb 2014 14:49:47 +0200
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From: jigsaw <jigsaw@gmail.com>
To: Stephen Hemminger <stephen@networkplumber.org>
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Subject: Re: [dpdk-dev] Is it possible to have dpdk running with no
 dependency on a nic ?
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Hi Stephen,

Have you tried link time optimization on DPDK application? Does it
decrease the I-cache miss rate evidently?

thx &
rgds,
-Qinglai

On Sun, Feb 16, 2014 at 9:02 PM, Stephen Hemminger
<stephen@networkplumber.org> wrote:
> On Fri, 14 Feb 2014 15:11:29 -0500
> Ymo Lists <ymolists@gmail.com> wrote:
>
>> "Enqueuing and dequeuing items from an rte_ring using the rings-based PM=
D
>> may be slower than using the native rings API. This is because Intel=AE =
DPDK
>> Ethernet drivers make use of function pointers to call the appropriate
>> enqueue or dequeue functions, while the rte_ring specific functions are
>> direct function calls in the code and are often inlined by the compiler.=
"
>>
>> Is that statement correct ? I would imagine that inlined code would be b=
e
>> faster than using function pointers ?
>
> Actually, the Intel DPDK has a bad case of inlineitis. The code for ring'=
s
> and other parts use inline on largish functions which bloats the code wit=
hout
> any perceivable gain in performance. The larger code causes more cache mi=
sses
> which actually hurt performance.  Also using GCC link time optimization h=
elps
> to reduce any need for inlining larger code bits.