there are a couple more, but again I would understand if those are deemed not important enough to keep it. device emulation of (non-ZNS) SSD block device die control: yes endurance groups would help but I am not aware of any vendor supporting it finer-grained control: 1000's of open blocks vs. a handful of concurrently open zones OOB area: helpful for L2P recovery On Thu, Jan 21, 2021 at 10:25 AM Matias Bjørling <mb@xxxxxxxxxxx> wrote: > > On 21/01/2021 17.58, Heiner Litz wrote: > > I don't think that ZNS supersedes OCSSD. OCSSDs provide much more > > flexibility and device control and remain valuable for academia. For > > us, PBLK is the most accurate "SSD Emulator" out there that, as > > another benefit, enables real-time performance measurements. > > That being said, I understand that this may not be a good enough > > reason to keep it around, but I wouldn't mind if it stayed for another > > while. > > The key difference between ZNS SSDs, and OCSSDs is that wear-leveling is > done on the SSD, whereas it is on the host with OCSSD. > > While that is interesting in itself, the bulk of the research that is > based upon OCSSD, is to control which dies are accessed. As that is > already compatible with NVMe Endurance Groups/NVM Sets, there is really > no reason to keep OCSSD around to have that flexibility. > > If we take it out of the kernel, it would still be maintained in the > github repository and available for researchers. Given the few changes > that have happened over the past year, it should be relatively easy to > rebase for each kernel release for quite a while. > > Best, Matias > > > > > > > On Thu, Jan 21, 2021 at 5:57 AM Matias Bjørling <mb@xxxxxxxxxxx> wrote: > >> On 21/01/2021 13.47, Jens Axboe wrote: > >>> On 1/21/21 12:22 AM, Pan Bian wrote: > >>>> The allocated page is not released if error occurs in > >>>> nvm_submit_io_sync_raw(). __free_page() is moved ealier to avoid > >>>> possible memory leak issue. > >>> Applied, thanks. > >>> > >>> General question for Matias - is lightnvm maintained anymore at all, or > >>> should we remove it? The project seems dead from my pov, and I don't > >>> even remember anyone even reviewing fixes from other people. > >>> > >> Hi Jens, > >> > >> ZNS has superseded OCSSD/lightnvm. As a result, the hardware and > >> software development around OCSSD have also moved on to ZNS. To my > >> knowledge, there is not anyone implementing OCSSD1.2/2.0 commercially at > >> this point, and what has been deployed in production does not utilize > >> the Linux kernel stack. > >> > >> I do not mind continuing to keep an eye on it, but on the other hand, it > >> has served its purpose. It enabled the "Open-Channel SSD architectures" > >> of the world to take hold in the market and thereby gained enough > >> momentum to be standardized in NVMe as ZNS. > >> > >> Would you like me to send a PR to remove lightnvm immediately, or should > >> we mark it as deprecated for a while before pulling it? > >> > >> Best, Matias > >> > >> >
