Greetings all, The first test results for Linux/iSCSI Initiators and targets for large block sizes using 10 Gb/sec Ethernet + PCIe device-passthrough into Linux/KVM guests have been posted at: http://linux-iscsi.org/index.php/KVM-LIO-Target So far, the results have been quite impressive using the Neterion X3100 series hardware with recent KVM-85 stable code (with Marcelo's patches, see the above link) on v2.6.29.2 KVM guests, and using v2.6.30-rc3 KVM Hosts. Using iSCSI RFC defined MC/S to scale a *single* KVM accessable Linux/iSCSI Logical Unit to 10 Gb/sec line-rate speeds has been successful using Core-iSCSI WRITE/READ (bi-directional) traffic using Linux-Test-Project disktest pthreaded benchmark with O_DIRECT enabled. Using Core-iSCSI MC/S w/ iSCSI READ (uni-directional) the average is about 6-7 Gb/sec, and with MC/S iSCSI WRITE (uni-directional) the average is about 5 Gb/sec to the RAMDISK_DR and FILEIO storage objects for these same streaming tests. Please see the link for more information on the tests and hardware/software setup. The tests have been run with both upstream Open-iSCSI and Core-iSCSI Initiators against Target_Core_Mod/LIO-Target v3.0 in KVM guests. It is important to note that these tests have been run with tcp_sendpage() disabled (tcp_sendpage() is enabled by default in LIO-Target and Open-iSCSI) in 10 Gb/sec KVM guests, which have been disable into order to get up running with the 10 Gb/sec hardware. 1 Gb/sec e1000e ports are stable with sendpage() in LIO-Target KVM guests, and these will be enabled in 10 Gb/sec hardware in subsequent tests. Also note that Open-iSCSI WRITEs using tcp_sendpage() have been ommited for this first run of tests. It is also important to note that both iSCSI MC/S and dm-multipath are methods to allow a single Linux/SCSI Logical Unit to scale across multiple TCP connections using the iSCSI Protocol. Both of these methods (iSCSI RFC fabric level multiplexing and OS-level SCSI Multipath) allow for means for scaling across multiple X3110 Vpaths (MSI-X TX/RX pairs), and MC/S is a method that has a low amount of overhead. Some of the future setups for KVM + 10 Gb/sec will be using dm-multipath block devices, 10 Gb/sec Ethernet PCIe multi-function mode into KVM guest, as well as PCIe SR-IOV on recent IOMMU capable hardware platforms. Many thanks to the Neterion folks and Sheng Yang for answering my questions! --nab -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
