netdev - RE: [RFC 0/7] Add support to process rx packets in thread

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Message-ID: <000201d66182$8989a3b0$9c9ceb10$@codeaurora.org>
Date:   Fri, 24 Jul 2020 11:50:27 +0530
From:   "Rakesh Pillai" <pillair@...eaurora.org>
To:     "'Florian Fainelli'" <f.fainelli@...il.com>,
        "'Andrew Lunn'" <andrew@...n.ch>
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



> -----Original Message-----
> From: Florian Fainelli <f.fainelli@...il.com>
> Sent: Friday, July 24, 2020 12:33 AM
> To: Rakesh Pillai <pillair@...eaurora.org>; 'Andrew Lunn'
> <andrew@...n.ch>
> 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 7/23/20 11:21 AM, Rakesh Pillai wrote:
> >
> >
> >> -----Original Message-----
> >> From: Florian Fainelli <f.fainelli@...il.com>
> >> Sent: Tuesday, July 21, 2020 11:35 PM
> >> 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?
> >
> > Hi Florian,
> > Yes, the affinity of IRQ does work for me.
> > But the affinity of IRQ does not happen runtime based on load.
> 
> It can if you also run irqbalance.


Hi Florian,

Is it some kernel feature ?  Sorry I am not aware of this ?
I know it can be done in userspace.

> --
> Florian