Re: [dpdk-dev] Is it possible to have dpdk running with no dependency on a nic ?

[jigsaw <jigsaw@gmail.com>]

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 PMD
>> may be slower than using the native rings API. This is because Intel® 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 be
>> 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 without
> any perceivable gain in performance. The larger code causes more cache misses
> which actually hurt performance.  Also using GCC link time optimization helps
> to reduce any need for inlining larger code bits.