Re: [PATCH net-next V1] net: adjust net_device layout for cacheline usage

On Fri, 29 Jan 2021 15:00:58 +0100
Jesper Dangaard Brouer [off-list ref] wrote:

On Fri, 29 Jan 2021 14:33:02 +0100
Eric Dumazet [off-list ref] wrote:

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On 1/26/21 6:39 PM, Jesper Dangaard Brouer wrote:  

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The current layout of net_device is not optimal for cacheline usage.

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@@ -1877,6 +1876,23 @@ struct net_device {

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+
 	netdev_features_t	features;
 	netdev_features_t	hw_features;
 	netdev_features_t	wanted_features;    

Probably wanted_features, hw_features are not used in fast path, only
in control path ?  

Yes, that was also my analysis.  I did consider moving those down, but
I wanted to keep the first iteration simple ;-)

I've send a followup[1] to address this, thanks for pointing it out.

[1] https://patchwork.kernel.org/project/netdevbpf/patch/161313782625.1008639.6000589679659428869.stgit@firesoul/
-- 
Best regards,
  Jesper Dangaard Brouer
  MSc.CS, Principal Kernel Engineer at Red Hat
  LinkedIn: http://www.linkedin.com/in/brouer