Re: [PATCH v7 0/5] Support for Open-Channel SSDs

From: Matias BjÃrling
Date: Wed Sep 02 2015 - 06:59:55 EST


Any feedback is greatly appreciated.

Hi Matias,
After a reading of your code, that's a great idea.
I tried it with null_nvm and qemu-nvm. I have two questions
here.

Hi Yang, thanks for taking a look. I appreciate it.

(1), Why we name it lightnvm? IIUC, this framework
can work for other flashes not only NVMe protocol.

Indeed, there are people that work on using it with rapidio. It can also work with SATA/SAS, etc.

The lightnvm name came from the technique to offload devices (which contains non-volatile memory) so they only care about managing the media. In that sense "light" nvm. I'm open to other suggestions. I really wanted the OpenNVM / OpenSSD name, but they where already taken.

(2), There are gc and bm, but where is the wear leveling?
In hardware?

It should be implemented within each target. The rrpc module implements it within its gc routines. Currently rrpc only looks at the least about of invalid pages. The PE cycles should also be taken into account. Properly some weighted function to decide the cost. Similar to the cost-based gc used in the DFTL paper.


Thanx
Yang
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