[Disksim-users] subdivide latency

[John Bucy]

On 7/13/06, Shahrukh Rohinton Tarapore <shahrukh at cs.virginia.edu> wrote:
> Is it possible to subdivide the latency of a request? For example, if a
> request takes 3ms. then is there a mechanism for knowing that 1.5ms
> where spent on the disk mechanics, 0.5ms. were in some adapter or bus,
> and 1.0ms. some other overhead.  I really just want to be able to
> subdivide the latency between disk mechanics and the datas transmission
> through the logical/physical organization. Thanks.

I don't think that this functionality exists presently though the
usual quick/hacky solution would be to put some prints in.  Also,
remember that a lot of these activities are overlapped with each other
which makes this a little harder to think about.

At a lower level, the diskmodel API does expose this (look for 'struct
dm_mech_acctimes' in diskmodel/dm.h) but that won't give you
cache/controller/bus/etc, just mechanics.



john