linux-kernel - Re: [RFC 0/7] Add support to process rx packets in thread

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Message-ID: <f6d93d76-9e59-c257-9318-31c71df28018@gmail.com>
Date:   Tue, 21 Jul 2020 11:05:03 -0700
From:   Florian Fainelli <f.fainelli@...il.com>
To:     Andrew Lunn <andrew@...n.ch>,
        Rakesh Pillai <pillair@...eaurora.org>
Cc:     ath10k@...ts.infradead.org, linux-wireless@...r.kernel.org,
        linux-kernel@...r.kernel.org, kvalo@...eaurora.org,
        johannes@...solutions.net, davem@...emloft.net, kuba@...nel.org,
        netdev@...r.kernel.org, dianders@...omium.org, evgreen@...omium.org
Subject: Re: [RFC 0/7] Add support to process rx packets in thread

On 7/21/20 10:25 AM, Andrew Lunn wrote:
> On Tue, Jul 21, 2020 at 10:44:19PM +0530, Rakesh Pillai wrote:
>> NAPI gets scheduled on the CPU core which got the
>> interrupt. The linux scheduler cannot move it to a
>> different core, even if the CPU on which NAPI is running
>> is heavily loaded. This can lead to degraded wifi
>> performance when running traffic at peak data rates.
>>
>> A thread on the other hand can be moved to different
>> CPU cores, if the one on which its running is heavily
>> loaded. During high incoming data traffic, this gives
>> better performance, since the thread can be moved to a
>> less loaded or sometimes even a more powerful CPU core
>> to account for the required CPU performance in order
>> to process the incoming packets.
>>
>> This patch series adds the support to use a high priority
>> thread to process the incoming packets, as opposed to
>> everything being done in NAPI context.
> 
> I don't see why this problem is limited to the ath10k driver. I expect
> it applies to all drivers using NAPI. So shouldn't you be solving this
> in the NAPI core? Allow a driver to request the NAPI core uses a
> thread?

What's more, you should be able to configure interrupt affinity to steer
RX processing onto a desired CPU core, is not that working for you somehow?
-- 
Florian