Chuck Tuffli <ctuffli@xxxxxxxxx> writes: > On Thu, Mar 29, 2012 at 10:14 AM, Chris Worley <worleys@xxxxxxxxx> wrote: >> Sequential merging? Try "randread" instead. > > Great suggestion. Doing some additional analysis, it does appear that > IO's are probably getting merged as I see individual IO requests on > the wire of 2-4KB. > > Googling around this area seems to suggest this kernel behavior isn't > something I can disable. So if I honest to goodness *only* want 512B > IO, is ioengine=sg the best route? Try setting /sys/block/sdX/queue/nomerges to 2. That should completely disable merging. Cheers, Jeff -- 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
