On Sun, Feb 21, 2016 at 12:24 PM, Boaz Harrosh <boaz@xxxxxxxxxxxxx> wrote: > On 02/21/2016 09:51 PM, Dan Williams wrote: > <> >>> Please advise? >> >> When this came up a couple weeks ago [1], the conclusion I came away >> with is > > I think I saw that talk, no this was not suggested. What was suggested > was an FS / mount knob. That would break semantics, this here does not > break anything. No, it was a MAP_DAX mmap flag, similar to this proposal. The difference being that MAP_DAX was all or nothing (DAX vs page cache) to address MAP_SHARED semantics. > >> that if an application wants to avoid the overhead of DAX >> semantics it needs to use an alternative to DAX access methods. Maybe >> a new pmem aware fs like Nova [2], or some other mechanism that >> bypasses the semantics that existing applications on top of ext4 and >> xfs expect. >> > > But my suggestion does not break any "existing applications" and does > not break any semantics of ext4 or xfs. (That I can see) > > As I said above it perfectly co exists with existing applications and > is the best of both worlds. The both applications can write to the > same page and will not break any of application's expectation. Old or > new. > > Please point me to where I'm wrong in the code submitted? > > Besides even an FS like Nova will need a flag per vma like this, > it will need to sort out the different type of application. So > here is how this is communicated, on the mmap call, how else? > And also works for xfs or ext4 > > Do you not see how this is entirely different then what was > proposed? or am I totally missing something? Again please show > me how this breaks anything's expectations. > What happens for MAP_SHARED mappings with mixed pmem aware/unaware applications? Does MAP_PMEM_AWARE also imply awareness of other applications that may be dirtying cachelines without taking responsibility for making them persistent? -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>