* RT metric sharing...
@ 2009-12-10 22:14 David Miller
2009-12-11 0:22 ` Eric Dumazet
0 siblings, 1 reply; 2+ messages in thread
From: David Miller @ 2009-12-10 22:14 UTC (permalink / raw)
To: netdev
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).
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: RT metric sharing...
2009-12-10 22:14 RT metric sharing David Miller
@ 2009-12-11 0:22 ` Eric Dumazet
0 siblings, 0 replies; 2+ messages in thread
From: Eric Dumazet @ 2009-12-11 0:22 UTC (permalink / raw)
To: David Miller; +Cc: netdev
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)
^ permalink raw reply [flat|nested] 2+ messages in thread
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