Re: [PATCH 0/4] Fix routing metrics
From: Steffen Klassert <steffen.klassert@secunet.com>
Date: 2012-02-08 07:30:40
On Mon, Feb 06, 2012 at 03:29:16PM -0500, David Miller wrote:
Thinking about this, it seems overkill to check this on every metric access. You have an opportunity to validate metrics when the peer is bound to the route. This is because any change to the FIB metrics, is in turn a change to the FIB, which therefore invalidates the entire routing cache. So you can be sure that a new route cache entry will be created, and at that creation time you can ensure that we'll respect the updated FIB metrics if encessary.
Not sure if I get you right here, but that's what this patchset does. It invalidates the metrics on the peer by incrementing peer_genid in rt_cache_invalidate() which is invoked on every FIB change. Then, on slowpath route lookup it checks in rt_init_metrics() whether the peer_genid changed. If it changed, it exchanges the invalidated merics with new ones and copies the informations from the FIB into it.