Re: Call for testers with NVMe

On 02.09.26 11:41, Abdelkader Boudih wrote:

> Hi all,
>
> I am about to land the D59156 stack in about 24 hours: 
> https://reviews.freebsd.org/D59156
>
> It is a stack of 6 commits, D59151 --> D59156.
>
> This stack allows NVMe drives to run at full speed and use all 
> available lanes, instead of being quirked to use only one.
>
> Older NVMe drives will probably see no performance improvement. People 
> with modern NVMe drives can see improvements between 2x and 13x. (from 
> tests)
>
> On Apple machines, I measured up to 7.2x. Entreprise drive went from 
> 800MB/s to 12GB/s in a PCIe-5 slot.
>
> The system itself doesnt become 7x faster, but file transfers and 
> disk-heavy workloads become snappier.
>
> I'd like people to test the stack, or at least be aware that the next 
> update will have it.
>
> I have tested it with over 40 different NVMe models. The only 
> problematic one was the Apple T1 S3X NVMe, which wedged during 
> testing. It already has a quirk.
>
> So, to avoid anyone being unhappy that such a blessing landed without 
> warning, here is the warning. :)
>
I fail to see how the six patches are supposed to change the negotiated 
link width of NVMe drivers attached via PCIe. Does the claimed 
improvement in throughput and "snappiness" come purely from queuing the 
right number of requests in flight? Which hardware did you use for 
testing? Do you have a recommended test regime e.g. just dd, mount + tar 
to /dev/null, a specific fio invocation?

-- Jan Bramkamp