Linux 5.7 Will Let You Setup A Swap File Over A Network With SMB3/Samba

[phoronix]

Phoronix: Linux 5.7 Will Let You Setup A Swap File Over A Network With SMB3/Samba

A last minute feature coming into the Linux 5.7 kernel on its last day of the merge window is experimental support for allowing a remote swap setup over a network using SMB3...

http://www.phoronix.com/scan.php?page=news_item&px=Linux-57-Experimental-SMB3-Swap

[ljward]

Page fault, please reboot your router!

[Vorpal]

I'm trying to imagine a use case for this, and I'm coming up blank. Anyone has any suggestions?

[accumulator]

This headline is exactly what I expected eventually would happen, when I started using Linux in 1996.

[caligula]

So when does one need to enable swap over a network filesystem in 2020? Just curious.

[duby229]

So when does one need to enable swap over a network filesystem in 2020? Just curious.

In this case it's when you have access to an SMB3 fs, but no access to a local block device.v We all know linux is totally broken in out of memory situations. Sometimes you need swap space and if the only option is SMB3, that's what this is for.

[edwaleni]

This makes sense being that Linux supports multi-level paging and setting priorities on each level.

Setting a tiered page set on a 800Gbs Ethernet or a future Terabit+ backbone to some large fault tolerant flash array.

The only concern would be where the CPU is significantly tasked, NFS and SMB tend to delay their responses to status which could break the page and cause a fault.

[cynic]

So when does one need to enable swap over a network filesystem in 2020? Just curious.

when you want to hibernate your office PC but don't want to waste 32GB of precious SSD space for the swap!

[skeevy420]

when you want to hibernate your office PC but don't want to waste 32GB of precious SSD space for the swap!

That's what swap files are for.

[jabl]

The problem, traditionally, with these swap-over-network schemes (NFS, NBD, whatever) is that the network stack frequently needs to allocate memory for buffers etc. So if the swapping is triggered by the kernel failing to allocate memory, then you can have a deadlock.

Yes, it's possible to work around this, but, again, that's tedious work. Hopefully somebody's done it.