Looking for help of confusing IO performance issues.
I've done a disk IO performance test under SUSE Linux Enterprise Server 12, the result is very confusing.
In order to avoid the bottleneck of the physical disk, I set up a loop disk of 10G size at /dev/shm. The test tool is IOMeter linux edition, module is 100%random/60%write/40%read, block size is 4K.
I tested three times under the default kernel, and another three times in domain 0 under the xen kernel.
The maximum IOPS under default kernel is almost 90k, and the average is about 60k.
The maximum IOPS in domain 0 under xen kernel is almost 55K， and the average is about 35K.
Does anyone have encountered this issue yet, or please give me some advice to resolve it.