Re: Periodic messages on NetBSD-9 and -current: xennet0: rx no cluster

[Manuel Bouyer <bouyer%antioche.eu.org@localhost>]

On Thu, Jun 23, 2022 at 01:48:55PM -0700, Brian Buhrow wrote:
> 	hello.  In looking at the if_xennet_xenbus.c file, I see where the if_xennetrxbuf_cache is
> initialized, but I don't see where data is put into it before it's requested.  Is the idea that
> the items in the cache are supposed to be provided by the backend, i.e. the dom0?  Is it
> possible that dom0 isn't providing enough rx requests to satisfy the traffic it's sending us? I
> think I understand what's supposed to happen once traffic begins flowing:  rx requests come in,
> if_xennet_xenbus processes them and pushes them back into the if_xennetrxbuf_cache cache.   and
> pushes them back into the if_xennetrxbuf_cache cache.  What I don't understand is how the
> initial cache gets populated with free rx requests to use in order to get things started.

a pool cache has a backing pool. If there's no item in the pool cache, it
gets some memory from its backing pool.
The point of the cache here it to keep the physical address of items around,
so it doesn't have to be computed again

-- 
Manuel Bouyer <bouyer%antioche.eu.org@localhost>
     NetBSD: 26 ans d'experience feront toujours la difference
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