On 07/04/2018 07:06 PM, Federico Sbalchiero wrote: > Hi, > first I want to say thanks to everyone involved in Xenomai for their job. > > I'm testing Xenomai 3.0.7 and ipipe-arm/4.14 on Freescale/NXP i.MX6q > sabresd board using Yocto. System boots fine and is stable, but latency > under load (xeno-test) is higher than in my reference system (Xenomai > 2.6.5 on Freescale kernel 3.10.17 + ipipe 3.10.18). > This is after disabling power management, frequency scaling, CMA, > graphics, tracing, debug. > > I have found that a simple non-realtime user space process writing a > buffer in memory (memwrite) is able to trigger such high latencies. > Latency worsen a lot running a copy of the process on each core. > There is a correlation between buffer size and cache size suggesting > an L2 cache issue, like the L2 write allocate discussed in the mailing > list, but I can confirm L2 WA is disabled (see log). > > I'm looking for comments or suggestions. >
A basic dd if=/dev/zero of=/dev/null loop in the background is enough to raise the latency actually. Could you try the Xenomai 3 + 3.18 combo on your hw and let us know whether you see the same regression? TIA, -- Philippe. _______________________________________________ Xenomai mailing list [email protected] https://xenomai.org/mailman/listinfo/xenomai
