On 7/23/20 11:21 AM, Rakesh Pillai wrote:
>
>
>> -----Original Message-----
>> From: Florian Fainelli <[email protected]>
>> Sent: Tuesday, July 21, 2020 11:35 PM
>> To: Andrew Lunn <[email protected]>; Rakesh Pillai <[email protected]>
>> Cc: [email protected]; [email protected]; linux-
>> [email protected]; [email protected]; [email protected];
>> [email protected]; [email protected]; [email protected];
>> [email protected]; [email protected]
>> 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.
--
Florian
> -----Original Message-----
> From: Florian Fainelli <[email protected]>
> Sent: Friday, July 24, 2020 12:33 AM
> To: Rakesh Pillai <[email protected]>; 'Andrew Lunn'
> <[email protected]>
> Cc: [email protected]; [email protected]; linux-
> [email protected]; [email protected]; [email protected];
> [email protected]; [email protected]; [email protected];
> [email protected]; [email protected]
> 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 <[email protected]>
> >> Sent: Tuesday, July 21, 2020 11:35 PM
> >> To: Andrew Lunn <[email protected]>; Rakesh Pillai
> <[email protected]>
> >> Cc: [email protected]; [email protected]; linux-
> >> [email protected]; [email protected];
> [email protected];
> >> [email protected]; [email protected]; [email protected];
> >> [email protected]; [email protected]
> >> 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
On 7/23/20 11:20 PM, Rakesh Pillai wrote:
>
>
>> -----Original Message-----
>> From: Florian Fainelli <[email protected]>
>> Sent: Friday, July 24, 2020 12:33 AM
>> To: Rakesh Pillai <[email protected]>; 'Andrew Lunn'
>> <[email protected]>
>> Cc: [email protected]; [email protected]; linux-
>> [email protected]; [email protected]; [email protected];
>> [email protected]; [email protected]; [email protected];
>> [email protected]; [email protected]
>> 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 <[email protected]>
>>>> Sent: Tuesday, July 21, 2020 11:35 PM
>>>> To: Andrew Lunn <[email protected]>; Rakesh Pillai
>> <[email protected]>
>>>> Cc: [email protected]; [email protected]; linux-
>>>> [email protected]; [email protected];
>> [email protected];
>>>> [email protected]; [email protected]; [email protected];
>>>> [email protected]; [email protected]
>>>> 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.
The kernel interface is /proc/<irq>/smp_affinity and the users-space
implementation resides here:
https://github.com/Irqbalance/irqbalance
--
Florian