On 1/15/2018 11:41 AM, Shahaf Shuler wrote:

Monday, January 15, 2018 1:34 PM, Ferruh Yigit:

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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.

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Not having it means possible performance degradation for some PMD

which rely on it.

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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.

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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 <redacted>

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