Re: [BUG?] bonding, slave selection, carrier loss, etc.
From: Ben Hutchings <hidden>
Date: 2012-02-13 20:24:09
On Mon, 2012-02-13 at 10:48 -0800, Stephen Hemminger wrote:
On Mon, 13 Feb 2012 12:16:59 -0600 Chris Friesen [off-list ref] wrote:quoted
On 02/11/2012 12:52 PM, Ben Hutchings wrote:quoted
On Fri, 2012-02-10 at 17:53 -0800, Jay Vosburgh wrote:quoted
Chris Friesen[off-list ref] wrote:quoted
quoted
quoted
The best solution would be for bonding to just register for notification of the link going down. Presumably most drivers should be doing that properly by now, and for devices that get interrupt-driven notification of link status changes this would allow the bonding code to react much quicker.A quick look at some drivers shows that at least acenic still doesn't do netif_carrier_off, so converting entirely to a notifier-based failover mechanism would break drivers that work today.[...] It might be worth having some sort of feature flag (in priv_flags) that indicates whether the driver updates the link state. Alternately, disable polling of a device once you see a notification.Just fix the drivers to update link state. The whole mii polling method of bonding is really leftover from the era of 10 years ago when network drivers were stupid and didn't handle carrier.
Lots of hardware doesn't generate link interrupts. Our SFC4000 was supposed to generate events for link changes, but this didn't work reliably and so we poll regularly in the driver. I think the older drivers fail to update carrier because of similar hardware limitations. If you want to remove link polling from the bonding driver then it has to live *somewhere*. Rather than requiring every affected driver to implement the timer or delayed work item, I would suggest you put that in the networking core and then require drivers to either provide a link polling function or specify that they don't require polling. Then export the obvious implementations using ethtool or MII so that drivers don't have to replicate those. Ben. -- Ben Hutchings, Staff Engineer, Solarflare Not speaking for my employer; that's the marketing department's job. They asked us to note that Solarflare product names are trademarked.