On 1/15/2018 11:02 AM, Shahaf Shuler wrote: > Monday, January 15, 2018 12:21 PM, Ferruh Yigit: >>> I think all of the 3 should be in a single patch. >>> The reason is that the convert patch should maintain the same offloads >> configuration needed for the application. >> >> Perhaps I am missing some details about "mbuf fast free" offload, can you >> please give more details about it, what does having or not having it mean? >> 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? > > > [1] > /**< Device supports optimization for fast release of mbufs. > * When set application must guarantee that per-queue all mbufs comes from > * the same mempool and has refcnt = 1. > */ > > >> >>> Before the convert patch the examples were using the default >> configuration set by the PMD. In there the txq flags were set to ignore ref >> count and to declare all mbufs are from the same pool. >>> The fast free Tx offload was added in order to keep this old offloads >> configuration. >>> >>>> >>>> Wouldn't be better to enable new offloadings in a separate patch, >>>> other than convert one? And I don't know if we want to enable that >>>> specific offload for all samples. >>> >>> As you can see, not all the examples has the FAST_FREE offloads, only the >> entitled ones (i.e. single mempool and no ref count). >>> For example, ipv4_multicast doesn't set this offload flag. >>> >
