If user want control the inflight IOs for the tested block device, for example set iodepth=16, and we can get result like following: IO depths: 1=0.1%, 2=0.1%, 4=0.1%, 8=0.1%, 16=100.0%, 32=0.0%, >=64=0.0% this result only means (16~31) IOs inflight, don't means requests inflight, if max_sectors_kb = 64KB, and we set bs=256KB, the number of inflight requests may reach to 64(if nr_request allow). So for user want to control the number of inflight requests, bs should less than max_sectors_kb. Signed-off-by: weiping zhang <zhangweiping@xxxxxxxxxxxxxxx> --- fio.1 | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/fio.1 b/fio.1 index 54d1b0f..b7f4466 100644 --- a/fio.1 +++ b/fio.1 @@ -1814,7 +1814,10 @@ engines may impose OS restrictions causing the desired depth not to be achieved. This may happen on Linux when using libaio and not setting `direct=1', since buffered I/O is not async on that OS. Keep an eye on the I/O depth distribution in the fio output to verify that the -achieved depth is as expected. Default: 1. +achieved depth is as expected. The iodepth is not same as block device's +inflight. If you want control block device's inflight number by this parameter, +you should make sure bs less than max_sectors_kb of that block device, otherwise +bs will be splitted into multiple requests at block layer. Default: 1. .TP .BI iodepth_batch_submit \fR=\fPint "\fR,\fP iodepth_batch" \fR=\fPint This defines how many pieces of I/O to submit at once. It defaults to 1 -- 2.9.4 -- 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
