On 3/30/2023 7:29 AM, Feifei Wang wrote: > Currently, the transmit side frees the buffers into the lcore cache and > the receive side allocates buffers from the lcore cache. The transmit > side typically frees 32 buffers resulting in 32*8=256B of stores to > lcore cache. The receive side allocates 32 buffers and stores them in > the receive side software ring, resulting in 32*8=256B of stores and > 256B of load from the lcore cache. > > This patch proposes a mechanism to avoid freeing to/allocating from > the lcore cache. i.e. the receive side will free the buffers from > transmit side directly into its software ring. This will avoid the 256B > of loads and stores introduced by the lcore cache. It also frees up the > cache lines used by the lcore cache. And we can call this mode as buffer > recycle mode. > > In the latest version, buffer recycle mode is packaged as a separate API. > This allows for the users to change rxq/txq pairing in real time in data > plane, > according to the analysis of the packet flow by the application, for example: > ----------------------------------------------------------------------- > Step 1: upper application analyse the flow direction > Step 2: rxq_buf_recycle_info = rte_eth_rx_buf_recycle_info_get(rx_portid, > rx_queueid) > Step 3: rte_eth_dev_buf_recycle(rx_portid, rx_queueid, tx_portid, tx_queueid, > rxq_buf_recycle_info); > Step 4: rte_eth_rx_burst(rx_portid,rx_queueid); > Step 5: rte_eth_tx_burst(tx_portid,tx_queueid); > ----------------------------------------------------------------------- > Above can support user to change rxq/txq pairing at runtime and user does > not need to > know the direction of flow in advance. This can effectively expand buffer > recycle mode's > use scenarios. > > Furthermore, buffer recycle mode is no longer limited to the same pmd, > it can support moving buffers between different vendor pmds, even can put the > buffer > anywhere into your Rx buffer ring as long as the address of the buffer ring > can be provided. > In the latest version, we enable direct-rearm in i40e pmd and ixgbe pmd, and > also try to > use i40e driver in Rx, ixgbe driver in Tx, and then achieve 7-9% performance > improvement > by buffer recycle mode. > > Difference between buffer recycle, ZC API used in mempool and general path > For general path: > Rx: 32 pkts memcpy from mempool cache to rx_sw_ring > Tx: 32 pkts memcpy from tx_sw_ring to temporary variable + 32 > pkts memcpy from temporary variable to mempool cache > For ZC API used in mempool: > Rx: 32 pkts memcpy from mempool cache to rx_sw_ring > Tx: 32 pkts memcpy from tx_sw_ring to zero-copy mempool cache > Refer link: > http://patches.dpdk.org/project/dpdk/patch/20230221055205.22984-2-kamalakshitha.alig...@arm.com/ > For buffer recycle: > Rx/Tx: 32 pkts memcpy from tx_sw_ring to rx_sw_ring > Thus we can see in the one loop, compared to general path, buffer recycle > reduce 32+32=64 pkts memcpy; > Compared to ZC API used in mempool, we can see buffer recycle reduce 32 pkts > memcpy in each loop. > So, buffer recycle has its own benefits. > > Testing status: > (1) dpdk l3fwd test with multiple drivers: > port 0: 82599 NIC port 1: XL710 NIC > ------------------------------------------------------------- > Without fast free With fast free > Thunderx2: +7.53% +13.54% > ------------------------------------------------------------- > > (2) dpdk l3fwd test with same driver: > port 0 && 1: XL710 NIC > ------------------------------------------------------------- > Without fast free With fast free > Ampere altra: +12.61% +11.42% > n1sdp: +8.30% +3.85% > x86-sse: +8.43% +3.72% > ------------------------------------------------------------- > > (3) Performance comparison with ZC_mempool used > port 0 && 1: XL710 NIC > with fast free > ------------------------------------------------------------- > With recycle buffer With zc_mempool > Ampere altra: 11.42% 3.54% > ------------------------------------------------------------- >
Thanks for the perf test reports. Since test is done on Intel NICs, it would be great to get some testing and performance numbers from Intel side too, if possible. > V2: > 1. Use data-plane API to enable direct-rearm (Konstantin, Honnappa) > 2. Add 'txq_data_get' API to get txq info for Rx (Konstantin) > 3. Use input parameter to enable direct rearm in l3fwd (Konstantin) > 4. Add condition detection for direct rearm API (Morten, Andrew Rybchenko) > > V3: > 1. Seperate Rx and Tx operation with two APIs in direct-rearm (Konstantin) > 2. Delete L3fwd change for direct rearm (Jerin) > 3. enable direct rearm in ixgbe driver in Arm > > v4: > 1. Rename direct-rearm as buffer recycle. Based on this, function name > and variable name are changed to let this mode more general for all > drivers. (Konstantin, Morten) > 2. Add ring wrapping check (Konstantin) > > v5: > 1. some change for ethdev API (Morten) > 2. add support for avx2, sse, altivec path > > Feifei Wang (3): > ethdev: add API for buffer recycle mode > net/i40e: implement recycle buffer mode > net/ixgbe: implement recycle buffer mode > > drivers/net/i40e/i40e_ethdev.c | 1 + > drivers/net/i40e/i40e_ethdev.h | 2 + > drivers/net/i40e/i40e_rxtx.c | 159 +++++++++++++++++++++ > drivers/net/i40e/i40e_rxtx.h | 4 + > drivers/net/ixgbe/ixgbe_ethdev.c | 1 + > drivers/net/ixgbe/ixgbe_ethdev.h | 3 + > drivers/net/ixgbe/ixgbe_rxtx.c | 153 ++++++++++++++++++++ > drivers/net/ixgbe/ixgbe_rxtx.h | 4 + > lib/ethdev/ethdev_driver.h | 10 ++ > lib/ethdev/ethdev_private.c | 2 + > lib/ethdev/rte_ethdev.c | 33 +++++ > lib/ethdev/rte_ethdev.h | 230 +++++++++++++++++++++++++++++++ > lib/ethdev/rte_ethdev_core.h | 15 +- > lib/ethdev/version.map | 6 + > 14 files changed, 621 insertions(+), 2 deletions(-) > Is usage sample of these new APIs planned? Can it be a new forwarding mode in testpmd?
