All, I am trying to evaluate the behavior of some RAID controllers when faced with “bursty” IOs. Typically in our storage performance testing we evaluate controllers using a steady stream of I/Os by controlling the iodepth option and leaving the rest of the IO depth and IO rate parameters undefined so they take the defaults. The behavior I am trying to simulate is an application sending multiple IOs at once, retrieve + processing time and then submitting the next group of IOs. From the fio HOWTO document it looks like the best way to do this is: iodepth = (number of I/Os to send at once, i.e 32) iodepth_batch_submit = 0 (submit the full set of iodepth IOs at once) iodepth_batch_complete_min = 1 iodepth_batch_complete_max = iodepth (fio should try to retrieve at least a single IO and up to the iodepth number of IOs) iodepth_low = default (always fill the queue) thinktime = number of milliseconds between each burst thinktime_blocks = ? (This is where I was confused…do I set this to the iodepth so it will burst all iodepth IOs before waiting thinktime milliseconds? Or should this be set to 1 because I want the thinktime to occur after a single batch of IOs?) So I’m hoping the end behavior is along the lines of: · Send 32 IOs · Retrieve all 32 IOs · Wait 5 ms (will it continue to wait if all IOs from the previous batch have not been retrieved yet?) · Send the next 32 IOs, repeat I did read the HOWTO couple of times but just wanted clarification since I haven’t used fio in this manner before and did not want to assume my interpretation is correct. Jens indicated this is the best place to ask so figured I would give it a shot. Thanks for the help in advance. -- Jason Sirichoke Performance Analyst Datacenter Solutions Group (DCSG) Broadcom Ltd Phone: +1.719.533.7943 -- To unsubscribe from this list: send the line "unsubscribe fio" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
