[dpdk-dev] [PATCH v3 01/39] examples/l2fwd: convert to new ethdev offloads API

Ferruh Yigit ferruh.yigit at intel.com
Mon Jan 15 12:56:57 CET 2018


On 1/15/2018 11:41 AM, Shahaf Shuler wrote:
> Monday, January 15, 2018 1:34 PM, Ferruh Yigit:
>>>> Currently no PMD seems implemented it.
>>>
>>> Sure,
>>>
>>> FAST_FREE offload is the logical AND between the old txqflags of:
>>> ETH_TXQ_FLAGS_NOREFCOUNT
>>> ETH_TXQ_FLAGS_NOMULTMEM
>>>
>>> The offload is just a performance optimization. As specified in the
>> documentation [1] it enables the PMDs to further optimize the data path
>> given the guarantees from the application.
>>> Not having it means possible performance degradation for some PMD
>> which rely on it.
>>>
>>> There is no PMD which implement it yet since not all PMDs moved to the
>> new offloads API. However this flag is tested and translated into txqflags as
>> part of rte_eth_convert_txq_offloads function.
>>> Relevant PMDs for this offload will be: sfc, thunderx and i40e.
>>
>> Thank you for clarification, I am OK to have it.
>>
>> But since currently no PMD provide "DEV_TX_OFFLOAD_MBUF_FAST_FREE"
>> capability, and default txq_flags is overwritten, some PMDs lost this
>> optimization until they implement new capability, right?
> 
> Yes this is correct, a good motivation to convert :). 

My concern is being close to the integration deadline and if this patch cause
performance drop for some PMDs.
But I guess we can get the related PMD fixes almost until release if an issue
observed, so this gives time to PMD maintainers.

For series,
Reviewed-by: Ferruh Yigit <ferruh.yigit at intel.com>

> From the examples and testpmd part everything is ready. Just need for the PMD to report back the capability to have this offload. 
> 



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