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

From: "Rakesh Pillai" <pillair@codeaurora.org>
To: 'Florian Fainelli' <f.fainelli@gmail.com>,
	'Andrew Lunn' <andrew@lunn.ch>
Cc: netdev@vger.kernel.org, linux-wireless@vger.kernel.org,
	linux-kernel@vger.kernel.org, ath10k@lists.infradead.org,
	dianders@chromium.org, evgreen@chromium.org, kuba@kernel.org,
	johannes@sipsolutions.net, davem@davemloft.net,
	kvalo@codeaurora.org
Subject: RE: [RFC 0/7] Add support to process rx packets in thread
Date: Thu, 23 Jul 2020 23:51:08 +0530	[thread overview]
Message-ID: <002e01d6611e$0d8ac640$28a052c0$@codeaurora.org> (raw)
In-Reply-To: <f6d93d76-9e59-c257-9318-31c71df28018@gmail.com>

> -----Original Message-----
> From: Florian Fainelli <f.fainelli@gmail.com>
> Sent: Tuesday, July 21, 2020 11:35 PM
> To: Andrew Lunn <andrew@lunn.ch>; Rakesh Pillai <pillair@codeaurora.org>
> Cc: ath10k@lists.infradead.org; linux-wireless@vger.kernel.org; linux-
> kernel@vger.kernel.org; kvalo@codeaurora.org; johannes@sipsolutions.net;
> davem@davemloft.net; kuba@kernel.org; netdev@vger.kernel.org;
> dianders@chromium.org; evgreen@chromium.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.

> --
> Florian

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