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

[Rakesh Pillai]

> -----Original Message-----
> From: Florian Fainelli <f.fainelli@xxxxxxxxx>
> Sent: Tuesday, July 21, 2020 11:35 PM
> To: Andrew Lunn <andrew@xxxxxxx>; Rakesh Pillai <pillair@xxxxxxxxxxxxxx>
> Cc: ath10k@xxxxxxxxxxxxxxxxxxx; linux-wireless@xxxxxxxxxxxxxxx; linux-
> kernel@xxxxxxxxxxxxxxx; kvalo@xxxxxxxxxxxxxx; johannes@xxxxxxxxxxxxxxxx;
> davem@xxxxxxxxxxxxx; kuba@xxxxxxxxxx; netdev@xxxxxxxxxxxxxxx;
> dianders@xxxxxxxxxxxx; evgreen@xxxxxxxxxxxx
> 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