Hi all,
Most of you did well with the individual OPs and were able to find a fundamental problem of the system in the OP statement and give a solution.
To help you improve further in your group revision, we list below some common issues found in your ops which you should try to address:
Some of you misunderstood the OP statement:
Some of you thought of NVM as a NAND flash and is not byte-addressable, but the OP statement actually makes it clear that NVM is byte-addressable. For the OP, simply regard NVM as identical to the DRAM except that data stored on it persists across reboots.
Some of you assume that in the system proposed in the op statement, the whole stack is unchanged and unaware of the persistency of NVM, i.e., the system uses NVM like DRAM, and argues that the problem is that the system is wasteful when treating NVM as DRAM. However, the op statement mentions clearly that OS has been changed to extend the NVM to the persistent namespace. The system can already take advantage of the persistency of NVM in the way that if a file is loaded into memory and written to, it needs not be flushed back to disk for the changes to outlive the writing process. The op mainly expects you to identify problems related to transactions.
Many of you provided detailed solutions to the problem identified, but some of you did not. For example, instead of just saying “augment existing HTM with support to NVM”, you should explain exactly what additions will be made. In the revision, please provide sufficient details of your solution when allowed by the 500 words limit. Without such details, you cannot convince the readers that your solution will work.
Some of you discussed the trade-offs of the proposed solutions, but some did not. In the revision, please discuss the trade-offs, i.e., what are the pros/cons of your solution. You can think about points like performance and “intrusivity” (How intrusive is the solution? How many changes to the existing stacks do you need? If it requires changes in the application code, is it easy for programmers to do the changes?), just to name a few.
Best regards,
POCS staff
