On 17.05.2022 10:10, Christoph Hellwig wrote:
I'm a little surprised about all this activity.
I though the conclusion at LSF/MM was that for Linux itself there
is very little benefit in supporting this scheme. It will massively
fragment the supported based of devices and applications, while only
having the benefit of supporting some Samsung legacy devices.
I believed we had agreed that non-power-of-2 zoned devices was something
to explore. Let me summarize the 3 main points we covered at different
times at LSF/MM:
- This is not for legacy Samsung ZNS devices. At least 4 other
vendors have reported building non-power-of-2 ZNS devices to meet
customer demands on removing holes in the address space. It seems
like there will be more ZNS devices with size=capacity out there
than with PO2 sizes. Block device and FS support is very desirable
for these.
- We also talked about how the capacity not being a PO2 is the one
introducing the fragmentation, as applications that already worked
with SMR HDDs will have to change their data placement policy. The
size is just a construction, but the real work is adopting the
capacity.
- Besides the previous poit, the fragmentation will happen from the
moment we have available devices. This is not a kernel-only issue.
We have SMR, ZNS, and soon another spec for zone devices. I
understood that as long as we do not break any existing support, we
would be able to expend the zoned ecosystem in Linux.
So my impression was that this work, while technically feasible, is
rather useless. So unless I missed something important I have no
interest in supporting this in NVMe.
Does the above help you reconsidering your interest in supporting this
in NVMe?
