Hi Frank, thanks a lot for that input! Currently I'm switching to Ubuntu for my tests - hoping that /io_uring/ will help. But I will definitely try out pvsync2 as well. Thanks! Daniel Am 16.02.21 um 20:00 schrieb Ober, Frank: > Hi Daniel, Intel uses pvsync2 for QD1 testing so if you cannot use spdk or io_uring (these are the fastest ways to test a device), you can switch your engine to pvsync2 on this kernel and this will work. > > Here's what I tried on PCIe Gen3 system with an Optane drive and your drive. > > > [root@fm42adsdemo001 block]# fio --bs=1M --rw=randwrite --numjobs=1 --iodepth=1 --size=10000M \ >> --filename=/dev/nvme6n1 --name=mylittletest --direct=1 --fsync=1 \ >> --refill_buffers --ioengine=pvsync2 --group_reporting \ >> --fallocate=none --runtime=60 --time_based --hipri > mylittletest: (g=0): rw=randwrite, bs=(R) 1024KiB-1024KiB, (W) 1024KiB-1024KiB, (T) 1024KiB-1024KiB, ioengine=pvsync2, iodepth=1 > fio-3.24-5-g2ee2 > Starting 1 process > Jobs: 1 (f=1): [w(1)][100.0%][w=2048MiB/s][w=2048 IOPS][eta 00m:00s] > > I ran the same exact job on this mid-range Intel Xeon cpu and found io_uring only very slightly faster than pvsync2 > Jobs: 1 (f=1): [w(1)][100.0%][w=2057MiB/s][w=2057 IOPS][eta 00m:00s] > > HTH, > Frank Ober > > > -----Original Message----- > From: Jens Axboe > Sent: Sunday, February 14, 2021 8:50 AM > To: Daniel Menzel ; fio@vger.kernel.org > Subject: Re: io_uring on CentOS8? > > On 2/14/21 8:17 AM, Daniel Menzel wrote: >> /Somehow it seems as if I'm receiving messages from the mailing list - >> but mine do not seem to get through. So I'm trying again./ >> >> Hi, >> >> currently I started testing fairly fast NVMe-drives and I for the first time I dealt with the question whether the io engine is sufficient (up till now I just the default /libaio/). I found some information on io_uring online and now tried to switch to that engine: >> >> fio --bs=1M --rw=randwrite --numjobs=1 --iodepth=1  --size=10000M >> --filename=/dev/nvme0n1 --name=mylittletest --direct=1 --fsync=1  >> --refill_buffers --ioengine=io_uring --group_reporting >> --fallocate=none --runtime=60 --time_based --hipri >> >> But it crashes with the following information: fio: pid=2490, >> err=38/file:engines/io_uring.c:699, func=io_queue_init, error=Function >> not implemented >> >> My system: >> >> 1. fio-3.25 >> 2. CentOS8 (Kernel 4.18.0-240.1.1.el8_3.x86_64) 3. I have installed >> the packes liburing and liburing-devel >> >> Am I doing something wrong? > You are not, but since you get -ENOSYS from the system call, that means that the kernel doesn't support io_uring. It was officially added with the 5.1 kernel, so 4.18 predates that. > > > -- > Jens Axboe > -- Daniel Menzel Geschäftsführer Menzel IT GmbH Charlottenburger Str. 33a 13086 Berlin +49 (0) 30 / 5130 444 - 00 daniel.menzel@menzel-it.net https://menzel-it.net Geschäftsführer: Daniel Menzel, Josefin Menzel Unternehmenssitz: Berlin Handelsregister: Amtsgericht Charlottenburg Handelsregister-Nummer: HRB 149835 B USt-ID: DE 309 226 751