Thank you Philippe. I will try this, now I'm facing with other problems (I will send another mail for those). Only one note: for systems with L310 cache controller with version greater or equal to R3P2 (like iMX6SX) the "l2x0_write_allocate" kernel switch is useless (it's always overwritten in __l2c_init() call), will need a code edit to disable write-allocate.
Regards Mauro On Tue, 2017-01-31 at 10:34 +0100, Philippe Gerum wrote: > On 01/31/2017 09:28 AM, Mauro Salvini wrote: > > Hi, > > sorry, found myself the answer here: > > > > http://git.xenomai.org/ipipe.git/commit/?h=ipipe-4.1.y&id=a2a9a6148449095fa658a6d0d0cbed3308be2cfb > > > > So, should be L2 cache disabled for iMX6SX (that has a single core)? > > Not the entire cache, but you may want to try running with > write-allocate off using the "l2x0_write_allocate" kernel switch, since > cache coherence issues are not going to be relevant in this case. > > > > > Thanks again, regards > > Mauro > > > > On Tue, 2017-01-31 at 09:17 +0100, Mauro Salvini wrote: > >> Hi, > >> I'm working on a iMX6SX custom platform and I'm trying to use Xenomai on > >> top of it. > >> In the past, I tried Xenomai on a iMX6SX SabreSD demoboard using kernel > >> branch 4.1.15 from Freescale patched with Xenomai 3.0.1 (some little > >> rejections corrected by hand), and I was able to get a maximum latency > >> around 25us. > >> Now, using kernel 4.1.36 from Freescale Community (that integrates the > >> Freescale kernel branch) patched with Xenomai 3.0.3 I get maximum > >> latencies around 45us. > >> > >> Trying to figure out what is the source(s) of increased latencies, I > >> found these two kernel logs: > >> > >> [ 0.000000] L2C: I-pipe: revision >= L310-r3p2 detected, forcing WA. > >> [ 0.000000] L2C: I-pipe: write-allocate enabled, induces high > >> latencies. > >> > >> I wonder why L2C-310 cache controllers that are greater or equal to r3p2 > >> revision must be forced enabled. > >> > >> In past I read (and asked) in this mailing list that L2 cache should be > >> disabled to avoid higher latencies (as kernel log says). > >> > >> Thanks in advance, best regards > >> > >> Mauro > >> > >> > >> _______________________________________________ > >> Xenomai mailing list > >> Xenomai@xenomai.org > >> https://xenomai.org/mailman/listinfo/xenomai > > > > > > _______________________________________________ > > Xenomai mailing list > > Xenomai@xenomai.org > > https://xenomai.org/mailman/listinfo/xenomai > > > > _______________________________________________ Xenomai mailing list Xenomai@xenomai.org https://xenomai.org/mailman/listinfo/xenomai
