5.3 Merge window, part 2

Posted Jul 23, 2019 8:27 UTC (Tue) by unixbhaskar (guest, #44758)
Parent article: 5.3 Merge window, part 2

"There is a new mount option (nconnect=) for NFSv4 filesystems that allows the administrator to request that multiple TCP connections be established to the server. Traffic is then load-balanced across those connections. "

This is certainly getting over the lagging issue.

5.3 Merge window, part 2

Posted Jul 23, 2019 20:56 UTC (Tue) by Sesse (subscriber, #53779) [Link] (1 responses)

Or making it much worse by inducing bufferbloat.

5.3 Merge window, part 2

Posted Jul 24, 2019 0:43 UTC (Wed) by neilbrown (subscriber, #359) [Link]

> Or making it much worse by inducing bufferbloat.

Certainly possible. We would love to find a way to have the kernel auto-configure this number, but no brilliant ideas have come forward.

When you have parallel hardware (multiple cables, multiple DMA engines, multiple offload engines, multiple CPU cores), having multiple TCP connections can really help.
When you don't (or don't have enough), then multiple connections defeat congestion control and bloat buffers.

Determining the capabilities of the hardware (which could change) is, as yet, an unsolved challenge.