From: Eric Dumazet <eric.dumazet@gmail.com>
To: David Miller <davem@davemloft.net>
Cc: netdev@vger.kernel.org
Subject: Re: RT metric sharing...
Date: Fri, 11 Dec 2009 01:22:41 +0100 [thread overview]
Message-ID: <4B2190D1.9080505@gmail.com> (raw)
In-Reply-To: <20091210.141438.78359022.davem@davemloft.net>
Le 10/12/2009 23:14, David Miller a écrit :
>
> This topic has come up a few times, but I had a reason to
> consider it again.
>
> The routing metrics take up quite a bit of space in the
> dst_entry and thus every routing cache entry.
>
> We could save some space with indirection.
>
> Basically my idea is:
>
> 1) dst_metrics are maintained in external structure
>
> 2) when cache entry is created, read-only dst_metrics object
> is allocated for it
>
> 3) any attempt to change the metrics of such a read-only dst_entry
> cow's it, all further writes proceed as normal
>
> We currently have 13 (so 13 * sizeof(u32) == 52) and we're probably
> about to get a 14th (for the initial receive window stuff).
>
Nice idea Dave.
(Note : we do have a hole available for the 14th metric
because of forced __refcnt alignement)
prev parent reply other threads:[~2009-12-11 0:22 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-12-10 22:14 RT metric sharing David Miller
2009-12-11 0:22 ` Eric Dumazet [this message]
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