Prefetch not supported

[RobertSpir]

Any file stored on BTRFS volume is not cached in Windows read cache in RAM, needing to read files from disk over and over.

you can use RAMMap File Summary tab to check which files are cached in RAM and Empty Standby List option from Empty menu to clear windows read cache.

To get some big file to cache, you can do cat file.big > /dev/null in cygwin shell (or copy-paste the file)

On NTFS, the file will be cached making any subsequent read very fast by reading the data from RAM, but this does not work on BTRFS and the file needs to be read from disk again.

This is actually heavily crippling the performance when working with large datasets on BTRFS volume with enough RAM to cache them.

[maharmstone]

Thanks. Hmm, I see what you mean - it's caching memory-mapped files, such as EXEs, but not other stuff. I'll look into it.

[maharmstone]

Okay, so caching itself appears to be working fine - for open files. This appears to be something else: Windows is keeping NTFS files around after they've been closed, but not doing the same for Btrfs. I suspect this is Prefetch.

[maharmstone]

Closing old issues