netdev - RE: [PATCH net-next 1/4] ice: lower CPU usage of the GNSS read thread

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Date:   Tue, 4 Apr 2023 09:25:21 +0000
From:   "Kolacinski, Karol" <karol.kolacinski@...el.com>
To:     mschmidt <mschmidt@...hat.com>,
        "intel-wired-lan@...ts.osuosl.org" <intel-wired-lan@...ts.osuosl.org>
CC:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "Brandeburg, Jesse" <jesse.brandeburg@...el.com>,
        "Nguyen, Anthony L" <anthony.l.nguyen@...el.com>,
        "Michalik, Michal" <michal.michalik@...el.com>,
        "Kubalewski, Arkadiusz" <arkadiusz.kubalewski@...el.com>,
        poros <poros@...hat.com>
Subject: RE: [PATCH net-next 1/4] ice: lower CPU usage of the GNSS read thread

On Sat, Apr 01, 2023 at 07:26:56PM +0200, Michal Schmidt wrote:
> A simple improvement would be to replace the "mdelay(10);" in
> ice_gnss_read() with sleeping. A better fix is to not do any waiting directly in the function and just requeue this delayed work as needed.
> The advantage is that canceling the work from ice_gnss_exit() becomes immediate, rather than taking up to ~2.5 seconds (ICE_MAX_UBX_READ_TRIES
> * 10 ms).
> 
> This lowers the CPU usage of the ice-gnss-<dev_name> thread on my system from ~90 % to ~8 %.
> 
> I am not sure if the larger 0.1 s pause after inserting data into the gnss subsystem is really necessary, but I'm keeping that as it was.

Hi Michal,

We were planning to upstream 20 ms sleep instead of 10 ms delay but your
solution looks better.
To align with our code, ICE_GNSS_POLL_DATA_DELAY_TIME could be increased
to 20 ms.

Thanks,
Karol