Hi Sebastian, On Thu, 6 Dec 2018 at 11:41, Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx> wrote: [...] > > BTW, playing with some options I discovered that if I add "nohz=off" > > to the kernel commandline I get a maximum latency of about 150us when > > using the i915 driver, and less than 100us when not using it. I am > > going to test your patch, and to disable debugging and tracing... I'll > > let you know the results. > > Is it better or worse with nohz=off? And do you get the backtrace? The latency with "nohz=off" is about 150us smaller than without this boot option. I did not get any other backtrace. Some preliminary tests show that disabling debug options and .config reduces the latency to less than 50us (but I am still running experiments). I'll also check if your patch allows to get the same latency values with and without the i915 driver. Thanks, Luca
