Received-SPF: pass (google.com: domain of linux-wireless-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Message-ID: <54589d98-882c-cee4-dd6d-140d50f400d0@nbd.name>
Date:   Tue, 10 May 2022 18:10:15 +0200
MIME-Version: 1.0
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:91.0)
 Gecko/20100101 Thunderbird/91.9.0
From:   Felix Fietkau <nbd@nbd.name>
Subject: Re: [PATCH] mac80211: Simplify queue selection
To:     Alexander Wetzel <alexander@wetzel-home.de>,
        Johannes Berg <johannes@sipsolutions.net>
Cc:     linux-wireless@vger.kernel.org,
        =?UTF-8?Q?Toke_H=c3=b8iland-J=c3=b8rgens?= =?UTF-8?Q?en?= 
        <toke@kernel.org>
References: <20220510155828.9406-1-alexander@wetzel-home.de>
Content-Language: en-US
In-Reply-To: <20220510155828.9406-1-alexander@wetzel-home.de>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit
Precedence: bulk

On 10.05.22 17:58, Alexander Wetzel wrote:
> Let iTXQ drivers also register four queues in netdev and move queue
> assignment to ndo_select_queue(), like it's done for other drivers.
> 
> This gets rid of a special case in mac80211 and also increases the
> chance that when we call skb_get_hash() the skb is still hot in the CPU
> buffers.
> 
> Signed-off-by: Alexander Wetzel <alexander@wetzel-home.de>

This has the disadvantage of requiring a redundant sta lookup in the tx 
path for iTXQ drivers. I think the CPU cost of that one is probably 
higher than any potential gain from calling skb_get_hash a bit earlier.

- Felix