netdev - Re: [PATCH net-next v2 0/9] net: bridge: convert bool options to bits

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Date:   Wed, 26 Sep 2018 17:04:03 +0300
From:   Nikolay Aleksandrov <nikolay@...ulusnetworks.com>
To:     netdev@...r.kernel.org
Cc:     roopa@...ulusnetworks.com, davem@...emloft.net,
        stephen@...workplumber.org, bridge@...ts.linux-foundation.org,
        idosch@...sch.org
Subject: Re: [PATCH net-next v2 0/9] net: bridge: convert bool options to bits

On 26/09/18 17:00, Nikolay Aleksandrov wrote:
> Hi,
> A lot of boolean bridge options have been added around the net_bridge
> structure resulting in holes and more importantly different cache lines
> that need to be fetched in the fast path. This set moves all of those
> to bits in a bitfield which resides in a hot cache line thus reducing
> the size of net_bridge, the number of holes and the number of cache
> lines needed for the fast path.
> The set is also sent in preparation for new boolean options to avoid
> spreading them in the structure and making new holes.
> One nice side-effect is that we avoid potential race conditions by using
> the bitops since some of the options were bits being directly set in
> parallel risking hard to debug issues (has_ipv6_addr).
> 
> Before:
>  size: 1184, holes: 8, sum holes: 30
> After:
>  size: 1160, holes: 3, sum holes: 7
> 
> Patch 01 is a trivial style fix
> Patch 02 adds the new options bitfield and converts the vlan boolean
>          options to bits
> Patches 03-08 convert the rest of the boolean options to bits
> Patch 09 re-arranges a few fields in net_bridge to further reduce size
> 
> v2: patch 09: remove the comment about offload_fwd_mark in net_bridge and
>     leave it in the last 4 bytes, thanks to Ido for spotting it

And obviously it's not in the last 4 bytes, but that's fine. That
must've said just: "leave it where it is now".

> 
> Stephen, I've added your reviewed-by in patches 01-08, only removed it
> from patch 09 as the patch has changed.
> 
> Thanks,
>  Nik
>