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

[Rakesh Pillai]

> -----Original Message-----
> From: Florian Fainelli <f.fainelli@xxxxxxxxx>
> Sent: Friday, July 24, 2020 12:33 AM
> To: Rakesh Pillai <pillair@xxxxxxxxxxxxxx>; 'Andrew Lunn'
> <andrew@xxxxxxx>
> 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 7/23/20 11:21 AM, Rakesh Pillai wrote:
> >
> >
> >> -----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.
> 
> 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