On Tue, May 03, 2016 at 06:12:07PM +0530, Jerin Jacob wrote: > Elements of struct rte_eth_dev used in the fast path. > Make struct rte_eth_dev cache aligned to avoid the cases where > rte_eth_dev elements share the same cache line with other structures. > > Signed-off-by: Jerin Jacob <jerin.jacob at caviumnetworks.com> > --- > v2: > Remove __rte_cache_aligned from rte_eth_devices and keep > it only at struct rte_eth_dev definition as suggested by Bruce > http://dpdk.org/dev/patchwork/patch/12328/ > --- > lib/librte_ether/rte_ethdev.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/lib/librte_ether/rte_ethdev.h b/lib/librte_ether/rte_ethdev.h > index 2757510..48f14d5 100644 > --- a/lib/librte_ether/rte_ethdev.h > +++ b/lib/librte_ether/rte_ethdev.h > @@ -1615,7 +1615,7 @@ struct rte_eth_dev { > struct rte_eth_rxtx_callback *pre_tx_burst_cbs[RTE_MAX_QUEUES_PER_PORT]; > uint8_t attached; /**< Flag indicating the port is attached */ > enum rte_eth_dev_type dev_type; /**< Flag indicating the device type */ > -}; > +} __rte_cache_aligned; > > struct rte_eth_dev_sriov { > uint8_t active; /**< SRIOV is active with 16, 32 or 64 > pools */ > --
Hi Jerin, have you seen a performance degradation due to ethdev elements sharing a cache line? I ask because, surprisingly for me, I actually see a performance regression when I apply the above patch. It's not a big change - perf reduction of <1% - but still noticable across multiple runs using testpmd. I'm using two 1x40G NICs using i40e driver, and I see ~100kpps less traffic per port after applying the patch. [CPU: Intel(R) Xeon(R) CPU E5-2699 v3 @ 2.30GHz] Testpmd cmd and output shown below. Regards, /Bruce $ sudo ./x86_64-native-linuxapp-gcc/app/testpmd -c C0000 -n 4 -- --rxd=512 --txd=512 --numa EAL: Detected 36 lcore(s) EAL: Probing VFIO support... PMD: nfp_net_pmd_init(): librte_pmd_nfp_net version 0.1 EAL: PCI device 0000:01:00.0 on NUMA socket 0 EAL: probe driver: 8086:1521 rte_igb_pmd EAL: PCI device 0000:01:00.1 on NUMA socket 0 EAL: probe driver: 8086:1521 rte_igb_pmd EAL: PCI device 0000:05:00.0 on NUMA socket 0 EAL: probe driver: 8086:154a rte_ixgbe_pmd EAL: PCI device 0000:05:00.1 on NUMA socket 0 EAL: probe driver: 8086:154a rte_ixgbe_pmd EAL: PCI device 0000:08:00.0 on NUMA socket 0 EAL: probe driver: 8086:154a rte_ixgbe_pmd EAL: PCI device 0000:08:00.1 on NUMA socket 0 EAL: probe driver: 8086:154a rte_ixgbe_pmd EAL: PCI device 0000:81:00.0 on NUMA socket 1 EAL: probe driver: 8086:1584 rte_i40e_pmd PMD: eth_i40e_dev_init(): FW 5.0 API 1.5 NVM 05.00.02 eetrack 80002281 EAL: PCI device 0000:88:00.0 on NUMA socket 1 EAL: probe driver: 8086:1584 rte_i40e_pmd PMD: eth_i40e_dev_init(): FW 5.0 API 1.5 NVM 05.00.02 eetrack 80002281 Configuring Port 0 (socket 1) Port 0: 68:05:CA:27:D4:4E Configuring Port 1 (socket 1) Port 1: 68:05:CA:27:D2:0A Checking link statuses... Port 0 Link Up - speed 40000 Mbps - full-duplex Port 1 Link Up - speed 40000 Mbps - full-duplex Done No commandline core given, start packet forwarding io packet forwarding - CRC stripping disabled - packets/burst=32 nb forwarding cores=1 - nb forwarding ports=2 RX queues=1 - RX desc=512 - RX free threshold=32 RX threshold registers: pthresh=8 hthresh=8 wthresh=0 TX queues=1 - TX desc=512 - TX free threshold=32 TX threshold registers: pthresh=32 hthresh=0 wthresh=0 TX RS bit threshold=32 - TXQ flags=0xf01 Press enter to exit Telling cores to stop... Waiting for lcores to finish... ---------------------- Forward statistics for port 0 ---------------------- RX-packets: 1940564672 RX-dropped: 1456035742 RX-total: 3396600414 TX-packets: 1940564736 TX-dropped: 0 TX-total: 1940564736 ---------------------------------------------------------------------------- ---------------------- Forward statistics for port 1 ---------------------- RX-packets: 1940564671 RX-dropped: 1456036082 RX-total: 3396600753 TX-packets: 1940564736 TX-dropped: 0 TX-total: 1940564736 ---------------------------------------------------------------------------- +++++++++++++++ Accumulated forward statistics for all ports+++++++++++++++ RX-packets: 3881129343 RX-dropped: 2912071824 RX-total: 6793201167 TX-packets: 3881129472 TX-dropped: 0 TX-total: 3881129472 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Done. Shutting down port 0... Stopping ports... Done Closing ports... Done Shutting down port 1... Stopping ports... Done Closing ports... Done Bye...
