Increment the route table gen count after a modify
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Authored by rstone on Jan 19 2018, 9:40 PM.

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rS328272: Increment the route table gen count after a modify

Summary

Increment the route table generation count after modifying a
route. This signals back to TCP connections that they need to
update their L2 caches as the gateway for their route may have
changed. This is a heavier hammer than is needed, strictly
speaking, but route changes will be unlikely enough that the
performance effects of invalidating all connection route caches
should be negligible.

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Buildable 14526
Build 14665: arc lint + arc unit

Event Timeline

rstone created this revision.Jan 19 2018, 9:40 PM

Herald added a subscriber: ae. · View Herald TranscriptJan 19 2018, 9:40 PM

Harbormaster completed remote builds in B14491: Diff 38223.Jan 19 2018, 9:40 PM

jim_netgate.com added a subscriber: jim_netgate.com.Jan 19 2018, 10:09 PM

Why is this necessary, or desirable? If a route that is cached is modified, that doesn't invalidate it. It should still be the best route if it was before.

I just realized that this is necessary when the L3 gateway changes. The L3 cache doesn't need to be invalidated, but L2 does. A comment to this effect would be helpful.

wollman added a subscriber: wollman.Jan 20 2018, 5:57 PM

Add comment explaining generation increment

Harbormaster completed remote builds in B14526: Diff 38315.Jan 22 2018, 4:17 PM

Looks good.

This revision is now accepted and ready to land.Jan 23 2018, 1:52 AM

Closed by commit rS328272: Increment the route table gen count after a modify (authored by rstone). · Explain WhyJan 23 2018, 3:16 AM

This revision was automatically updated to reflect the committed changes.

Herald added a subscriber: imp. · View Herald TranscriptJan 23 2018, 3:16 AM