block device benchmarking

Hi,

I'm fiddling with a hand-made block device based benchmarking thingie,
which I want to run random reads and writes of relatively small blocks
(somewhat similar to databases). I'm much less interested in measuring
throughput, but rather in latency. Besides varying block sizes, I'm also
testing with a varying number of concurrent threads and varying
read/write ratios. As a result, I'm interested in roughly the following
graphs:

* (single thread) i/o latency vs. seek distance
* (single thread) throughput vs. (accurator) position
* (single thread) i/o latency vs. no of concurrent threads
* total requests per second + throughput vs. no of concurrent threads
* total requests per second + throughput vs. read/write ratio
* total requests per second + throughput vs. block size
* distribution of access times (histogram)

(Of course, not all of these are relevant for all types of storages.)

Does there already exist a tool giving (most of) these measures? Am I
missing something interesting? What would you expect from a block device
benchmarking tool?

Regards

Markus Wanner