On 23/05/18 18:14, Ran Shalit wrote: > > > בתאריך יום ד׳, 23 במאי 2018, 07:19, מאת Seokhee Han <seokhee.han@xxxxxxx <mailto:seokhee.han@xxxxxxx>>: > > Hi, > > > On 23/05/18 06:17, Ran Shalit wrote: > > Hello, > > > > We are using same BSP , kernel 3.18.11 rt7, with 2 different hardwares: > > 1. kontron board - i7 cpu > > 2. portwell board. - atom cpu (E3845 ) > > The results are totally different with the same testing. > > > > In kontron the error is 11usec, while in portwell it is 2000usec . > > > > The results of portwell seems more than just bad - they same > > unbelievable, the error is VERY high (2msec). > > > > I've tried to find a benchmark which can support my results, but found > > no benchmark with ATOM. > I am now developing RT Linux system on minnowboard Turbot Quad Core board, > which adopts ATOM E3845 series SoC, and it shows above about 2ms worst-case > latency during cyclictest. So I try to detect SMI-related, kernel unaware, > hw latency using Linux kernel's hwlat tracer and it tells me that there are > couples of latency spikes (above 1000us) on the board. > > > > Hi Han, > > I see the 1.5 to 2 msec values every time I execute this test application > https://github.com/nma/preempt-rt/blob/master/test-rt.c > Can you please tell me if you get similiar results with this test application? > > Thanks > Ran > > Hi Ran, I've also got the similar results (under 3ms spikes) with test-rt.c on minnowboard. Thanks, Seokhee > > I think that most of them are SMI-related. However, because I am not familiar > with intel system, I could not find the right way yet to disable SMI. Morever, > as googling, disabling SMI on the intel system can make the system harmful, > because some actions with SMI are related with critical conditions of the system, > like critical thermal conditions. > > As you can see in the below link, you can also detect hw latency with hwlat tracer. > https://www.osadl.org/Create-a-frequency-plot-from-data-of-har.bash-script-for-hwlat-plots.0.html > > Seokhee > > Thank you for any suggestion. > > > > Ranran > > -- > > To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in > > the body of a message to majordomo@xxxxxxxxxxxxxxx <mailto:majordomo@xxxxxxxxxxxxxxx> > > More majordomo info at http://vger.kernel.org/majordomo-info.html > > > > -- To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
