Hello, While running performance tests to compare various iSCSI target implementations I noticed that tgtd processes data writes slower via iSCSI for a block transfer size of 1 MB than for 512 KB. Although such large block transfer sizes are irrelevant when a filesystem is mounted on top of an iSCSI target, I decided to report this anyway. Kernel version: 2.6.23.14 STGT version (target): 20071227. The target was set up such that a RAM disk of 2GB in size was exported via iSCSI. open-iscsi version (initiator): 2.0.865-1 Performance related settings on the iSCSI initiator: node.session.iscsi.FirstBurstLength = 262144, node.session.iscsi.MaxBurstLength = 16776192, node.conn[0].iscsi.MaxRecvDataSegmentLength = 131072 and node.conn[0].tcp.window_size = 524288. Test commands that were run on the initiator: dd if=/dev/zero of=/dev/sde bs=512K oflag=direct dd if=/dev/zero of=/dev/sde bs=1M oflag=direct Results on Ethernet: For a block size of 512 KB: write throughput of 43 MB/s. For a block size of 1 MB: write throughput of 15 MB/s. Results on with IPoIB: For a block size of 512 KB: write throughput of 95 MB/s. For a block size of 1 MB: write throughput of 26 MB/s. Bart Van Assche. |