Sitsofe, Ok I will do that. Frank -----Original Message----- From: Sitsofe Wheeler <sitsofe@xxxxxxxxx> Sent: Wednesday, December 18, 2019 7:05 PM To: Ober, Frank <frank.ober@xxxxxxxxx> Cc: fio@xxxxxxxxxxxxxxx; Rajendiran, Swetha <swetha.rajendiran@xxxxxxxxx>; Liang, Mark <mark.liang@xxxxxxxxx>; Derrick, Jonathan <jonathan.derrick@xxxxxxxxx>; Vyas, Satvik M <satvik.m.vyas@xxxxxxxxx>; Knapp, Anthony J <anthony.j.knapp@xxxxxxxxx> Subject: Re: polled IO and 5.x kernels On Thu, 19 Dec 2019 at 02:40, Sitsofe Wheeler <sitsofe@xxxxxxxxx> wrote: > > On Wed, 18 Dec 2019 at 19:02, Ober, Frank <frank.ober@xxxxxxxxx> wrote: > > > > On 4.x kernels we used to be able to do: > > # echo 1 > /sys/block/nvme0n1/queue/io_poll > > > > And then run a polled_io job in fio with pvsync2 as our ioengine, with the hipri flag set. > > > > On 5.x kernels we see the following error trying to write the device > > settings>>> > > -bash: echo: write error: Invalid argument > > Wouldn't this be better asked on the linux-block mailing list > (http://vger.kernel.org/vger-lists.html#linux-block )? In fact, doing another search on that list (https://lore.kernel.org/linux-block/?q=io_poll ) or a more general Google search (https://www.google.com/search?q=%22echo%3A+write+error%3A+Invalid+argument%22+io_poll ) turns up a post titled "Error while enabling io_poll for NVMe SSD" (https://lore.kernel.org/linux-block/CAFQ9A4Zc8Fc4bDyAsiduTw4kTpxR=dVZr7LUdqUkvQSu1CaGpg@xxxxxxxxxxxxxx/ ) where Keith Busch (who has an Intel address but I'm guessing isn't in your group?) asks: "did the user turn on polling queues in the nvme driver"? Another quick hunt (https://github.com/torvalds/linux/search?q=%22poll_queues%22&type=Code and following some blame lines) finds https://github.com/torvalds/linux/commit/4b04cc6a8f86c4842314def22332de1f15de8523 which indicates an NVMe option was added in 5.0 related to polling. (PS: If you're using fio to publish benchmarking results don't forget about https://github.com/axboe/fio/blob/master/MORAL-LICENSE ) -- Sitsofe | http://sucs.org/~sits/
