VirtIO-FS DAX Support Close To Mainline For Offering Tremendous Performance Boost

[phoronix]

Phoronix: VirtIO-FS DAX Support Close To Mainline For Offering Tremendous Performance Boost

Judging from the latest FUSE Git activity, it's looking like the VirtIO-FS DAX patches that have been around since last year could be merged for Linux 5.10. This can provide a significant speed-up for those making use of this FUSE file-system for sharing files/folders with guest VMs...

http://www.phoronix.com/scan.php?page=news_item&px=VirtIO-FS-FUSE-DAX-Linux-5.10

[Danny3]

Wow, this would be really great!

[andrei_me]

Does it need some support from the host filesystem or application that might use it?

Or it is just free perf improvement?

[polarathene]

Wait, so the DAX mode is for the virtual filesystem, and unrelated to DAX support on the host filesystem? So a regular disk is fine, doesn't need to be persistent memory(pmem) like Optane?

[starshipeleven]

Wait, so the DAX mode is for the virtual filesystem, and unrelated to DAX support on the host filesystem? So a regular disk is fine, doesn't need to be persistent memory(pmem) like Optane?

it seems this is just bypassing guest disk caches and going directly in the host's, so it shouldn't care about the host filesystem, if the fuse "shared folder" worked before it will still work now.

[polarathene]

it seems this is just bypassing guest disk caches and going directly in the host's, so it shouldn't care about the host filesystem, if the fuse "shared folder" worked before it will still work now.

Wouldn't that be `cache=none`? The DAX features compliments that, just not clear how that works differently. On a host system DAX is only useful for PMEM storage isn't it? I'm not familiar enough with filesystems to know what else is involved if we've already had `cache=none`, DAX must be doing something else. Perhaps if the guest and host filesystems are the same, DAX is an optimization here to bypass any guest handling/management, sort of like a passthrough?