Ignore MAP_SYNC instead of unsupport it

NVSL / linux-nova

NOVA is a log-structured file system designed for byte-addressable non-volatile memories, developed at the University of California, San Diego.

http://nvsl.ucsd.edu/index.php?path=projects/nova

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Ignore MAP_SYNC instead of unsupport it #99

Closed pleiadesian closed 3 years ago

pleiadesian commented 3 years ago

To guarantee metadata consistency, applications will manually call many fsyncs after mmap with MAP_SYNC failed, as shown by this issue in pmdk. But in NOVA, metadata can be kept consistent without fsync or MAP_SYNC, so the fsyncs generated by applications are redundant and significantly decrease performance. So, I think to support MAP_SYNC and ignore it can match better with the behavior of other DAX-supporting file systems, as stated by this comment.

Andiry commented 3 years ago

I think NOVA should ignore MAP_SYNC. Care to send a PR? I can take a look at it but it may take a while.

pleiadesian commented 3 years ago

I'll handle it this weekend :)

Andiry commented 3 years ago

Really appreciate your help.