On Wed, May 27, 2020 at 4:54 PM Benjamin GAIGNARD <benjamin.gaignard@xxxxxx> wrote: > > > > On 5/27/20 2:48 PM, Benjamin GAIGNARD wrote: > > > > > > On 5/27/20 2:22 PM, Vincent Guittot wrote: > >> On Wed, 27 May 2020 at 13:17, Benjamin GAIGNARD > >> <benjamin.gaignard@xxxxxx> wrote: > >>> > >>> > >>> On 5/27/20 12:09 PM, Valentin Schneider wrote: > >>>> Hi Benjamin, > >>>> > >>>> On 26/05/20 16:16, Benjamin Gaignard wrote: > >>>>> A first round [1] of discussions and suggestions have already be > >>>>> done on > >>>>> this series but without found a solution to the problem. I resend > >>>>> it to > >>>>> progress on this topic. > >>>>> > >>>> Apologies for sleeping on that previous thread. > >>>> > >>>> So what had been suggested over there was to use uclamp to boost the > >>>> frequency of the handling thread; however if you use threaded IRQs you > >>>> get RT threads, which already get the max frequency by default (at > >>>> least > >>>> with schedutil). > >>>> > >>>> Does that not work for you, and if so, why? > >>> That doesn't work because almost everything is done by the hardware > >>> blocks > >>> without charge the CPU so the thread isn't running. I have done the > >>> tests with schedutil > >>> and ondemand scheduler (which is the one I'm targeting). I have no > >>> issues when using > >>> performance scheduler because it always keep the highest frequencies. > >> IMHO, the only way to ensure a min frequency for anything else than a > >> thread is to use freq_qos_add_request() just like cpufreq cooling > >> device but for the opposite QoS. This can be applied only on the > >> frequency domain of the CPU which handles the interrupt. > > I will give a try with this idea. > > Thanks. > > Adding freq_qos_add_request(FREQ_QOS_MIN) when starting streaming frames > solve my problem. I remove the request at the end of the streaming to > restore > the default value. You may as well add the request once at the init time with the request value set to PM_QOS_MIN_FREQUENCY_DEFAULT_VALUE initially and update it as needed going forward.
