On Thu, Apr 2, 2009 at 7:16 PM, Vladislav Bolkhovitin <vst@xxxxxxxx> wrote: > Bart Van Assche, on 04/02/2009 12:14 AM wrote: >> I have repeated some of these performance tests for iSCSI over IPoIB >> (two DDR PCIe 1.0 ConnectX HCA's connected back to back). The results >> for the buffered I/O test with a block size of 512K (initiator) >> against a file of 1GB residing on a tmpfs filesystem on the target are >> as follows: >> >> write-test: iSCSI-SCST 243 MB/s; IET 192 MB/s. >> read-test: iSCSI-SCST 291 MB/s; IET 223 MB/s. >> >> And for a block size of 4 KB: >> >> write-test: iSCSI-SCST 43 MB/s; IET 42 MB/s. >> read-test: iSCSI-SCST 288 MB/s; IET 221 MB/s. > > Do you have any thoughts why writes are so bad? It shouldn't be so.. It's not impossible that with the 4 KB write test I hit the limits of the initiator system (Intel E6750 CPU, 2.66 GHz, two cores). Some statistics I gathered during the 4 KB write test: Target: CPU load 0.5, 16500 mlx4-comp-0 interrupts per second, same number of interrupts processed by each core (8250/s). Initiator: CPU load 1.0, 32850 mlx4-comp-0 interrupts per second, all interrupts occurred on the same core. Bart. -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
