> -----Original Message----- > From: ext Ivan Khoronzhuk [mailto:ivan.khoronz...@linaro.org] > Sent: Tuesday, September 08, 2015 12:20 PM > To: Savolainen, Petri (Nokia - FI/Espoo); lng-odp@lists.linaro.org > Subject: Re: [lng-odp] [API-NEXT PATCH 3/5] linux-generic: cpu: rename > time_cycles to cpu_cycles > > > > On 08.09.15 11:35, Savolainen, Petri (Nokia - FI/Espoo) wrote: > > > > > >> -----Original Message----- > >> From: ext Ivan Khoronzhuk [mailto:ivan.khoronz...@linaro.org] > >> Sent: Tuesday, September 08, 2015 10:26 AM > >> To: Savolainen, Petri (Nokia - FI/Espoo); lng-odp@lists.linaro.org > >> Subject: Re: [lng-odp] [API-NEXT PATCH 3/5] linux-generic: cpu: > rename > >> time_cycles to cpu_cycles > >> > >> > >> > >> On 07.09.15 15:41, Petri Savolainen wrote: > >>> Implemented odp_cpu_cycles() be renaming odp_time_cycles() > >>> implementation. Time implementation uses odp_cpu_cycles > >>> temporarely. > >> > >> Right. You didn't add functional changes here. > >> Currently It's not documented that odp_time_cycles returns global > >> cycles ). > >> But time API does. So question is, on what I should replace this > >> function for > >> linux generic. on clock_gettime ? Which impact it will have on > >> applications/tests/examples? > >> Do we have choice? > > > > This series does not change time API or functionality of the > implementation, > > just adds CPU cycles API. The new time API needs to specify global > wall clock time > > and implement it so that it's globally synchronized (==> not use CPU > cycles counter > > any more, if those counters are not kept in sync by the HW) > +, or can be impacted by freq change. > > I'm afraid that it will be smth similar to timer API s/w counter. > Which has not very good resolution for short time measurements. > Do we have direct access to counters in linux-generic cases, like it's > done for cycles? >
It depends on HW and default access rights (linux) on the platform - but, yes some platforms will provide direct read access to the global time counter. I think an arch/linux implementation is enough for linux-generic at the moment. HW specific (arch/xxx) implementations can be added later on. -Petri _______________________________________________ lng-odp mailing list lng-odp@lists.linaro.org https://lists.linaro.org/mailman/listinfo/lng-odp
