[Disksim-users] Disksim performance

[John Carter]

Hi all -

   I am considering extending DiskSim to explore some ideas related
to improving storage system energy-efficiency using flash.  One
consideration is DiskSim's simulation performance, since I hope to
evaluate the ideas on traces with over 1B IOs.

   When I compile and run DiskSim on a 1M-entry trace file
(ascii.trace replicated 10X with the timestamps updated using the same
configuration as the runvalid test for ascii.trace), it takes 91
seconds to execute on 3.2GHz Xeon (quad-core, but I don't think that
matters since DiskSim is single-threaded, right?).  That translates
into a bit over 10K simulated IOPs, which is slower than real-time for
some of the high-end configurations I'd like to explore.  And it
translates into a little over 24 hours to simulation 1B IOs, which
could get painful.

   One of my colleagues asked Greg (Ganger) about DiskSim's
performance at FAST, and Greg apparently replied that 10K simulated
IOPs was slower than he would have predicted.  He further suggested
that I contact this list to see if it fits other people's experience.
What kind of simulation speeds are y'all seeing?  Obviously it depends
on the configuration being evaluated, but the ascii.parv configuration
did not look at all onerous.  Are there ways to improve simulation
performance that a new DiskSim user like myself might not have found?
For the DiskSim implementors out there, how tightly tuned is DiskSim's
performance -- has it already been tuned pretty hard (so there isn't
likely much more performance to squeeze out) or has performance tuning
not been a focus (so perhaps simulation speed could be improved a lot
if somebody were to focus on it)?

   Thanks for your input!

Cheers,
John