Hi, On 17 June 2018 at 01:57, shashank chaurasia <shashankch9009@xxxxxxxxx> wrote: > what is the bsrange upper limit that can be handled by fio properly? > > I sometimes see "invalid argument error" when I use > bsrange=1k-32M This is going to be down to the environment you're running (I shall assume Linux for the rest of this email), the hardware you are using, the ioengine you choose and the options you passed. If you are using direct I/O (I can't tell because you didn't include the whole job file/command line you using) then you cannot use a block size smaller than the device's minimum sector size (for some devices that may be 4kbytes). Additionally there's a maximum transfer size of the "disk" (/sys/block/<disk>/queue/max_sectors_kb) and there's the maximum size the kernel will use (/sys/block/sda/queue/max_sectors_kb ). Further, if you are choosing to transfer giant size blocks what's happening is you typically forcing the kernel to split the block up into little pieces for you (ideally the optimal_io_size which is generally much smaller than the maximum). If you aren't able to submit I/O asynchronously this can be a benefit (because you then get depth parallelism) but if you can, sending such large I/Os just pushing overhead into the kernel. Another problem area can be down to unrealistically high option values when everything is running together. For example, if you choose a high iodepth, direct I/O, an asynchronous I/O engine, giant blocks and tons of jobs your kernel may simply not have the resources to keep that number of resultant hardware I/Os in flight. -- Sitsofe | http://sucs.org/~sits/ -- 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
