Message-ID: <accc06d7-8472-77d4-6d90-1d40565989aa@nbd.name>
Date:   Sat, 4 Dec 2021 09:25:23 +0100
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Subject: Re: [RFC] mac80211: Mesh Fast xmit support
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To:     Sriram R <quic_srirrama@quicinc.com>,
        linux-wireless@vger.kernel.org
Cc:     johannes@sipsolutions.net
References: <1638583489-6518-1-git-send-email-quic_srirrama@quicinc.com>
From:   Felix Fietkau <nbd@nbd.name>
In-Reply-To: <1638583489-6518-1-git-send-email-quic_srirrama@quicinc.com>
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On 2021-12-04 03:04, Sriram R wrote:
> Support Fast xmit for mesh device types by caching the
> header corresponding to the ethernet DA and reusing
> the cached header (mac, mesh, llc) everytime the packet
> is intended for that DA.
> 
> This will avoid multiple path table lookups during header
> generation for a mesh packet tx.
> 
> Freshness of the header is verified by identifying change
> in mesh paths before using the header and corresponding
> changes to the header and cache entry is done on the fly.
> 
> Mutable fields of the header such as eth SA, tid, mesh SN,
> PN are updated for each xmit.
> 
> Each cache entry is about 100Bytes, least used/expired entries
> are periodically removed when cache gets almost full.
> Currently the size is set to 50 entries.
> 
> Driver needs to advertise NL80211_EXT_FEATURE_MESH_FAST_XMIT
> to enable this support and setup this cache.
Thanks for working on this! I will likely take a closer look at it soon.
One quick question: does this impose any extra requirements on the 
driver, or why does the driver need to advertise support for this?

- Felix