On 10/18/2005 08:14 PM Philippe Gerum wrote: > Wolfgang Grandegger wrote: >> On 10/18/2005 01:44 PM Philippe Gerum wrote: >> >>>Philippe Gerum wrote: >>> >>>>Wolfgang Grandegger wrote: >>>> >>>> >>>>>Hallo, >>>>> >>>>>attached you will find the results of Xemonai latency measurements on >>>>>various embedded PowerPC boards using MPC 8xx and AMCC 4xx processors, >>>>>from low to high end covering a worst case latency range from 25 to 225 >>>>>us. It also includes a comparison with RTAI 3.0r5 on the slowest CPU. >>>>>Here are some remarks and comments: >>>>> >>>>>- On low-end processor code size matters a lot and it's difficult to >>>>> beat RTAI/RTHAL. >>>>> >>>> >>>>Beat no, get closer, yes, probably. The good news is that looking at the >>>>figures, we do have a margin of improvement! :o> >>>> >>>>Btw, the nucleus can be configured so that the user-space threading >>>>engine is compiled out (i.e. CONFIG_XENO_OPT_PERVASIVE from the nucleus >>>>menu), which would be the corresponding profile to compare with klatency >>>>(i.e. sched_up). Disabling this option reduces the code size for the >>>>nucleus from: >>>> >>>> text data bss dec hex filename >>>> 66740 792 6540 74072 12158 >>>>nucleus/xeno_nucleus.ko >>>> >>>>to: >>>> >>>> text data bss dec hex filename >>>> 52596 576 3956 57128 df28 >>>>nucleus/xeno_nucleus.ko >>>> >>> >>>Disabling the periodic timer support which is unused for the klatency test >>>brings this down to: >>> >>> text data bss dec hex filename >>> 51040 544 3956 55540 d8f4 nucleus/xeno_nucleus.ko >> >> >> OK, here are the new figures with (*) >> >> CONFIG_XENO_OPT_PERVASIVE is not set >> CONFIG_XENO_HW_PERIODIC_TIMER is not set: >> >> |-----lat min|-----lat avg|-----lat max|-overrun|---test-time >> RTAI 3.0r5 | 23120| 31838| 70520| ?| 00:12:26 >> Xenomai | 50560| 98976| 199040| 0| 00:09:45 >> Xenomai (*)| 44160| 96215| 200640| 0| 00:09:53 >> >> The min latency decreases as expected. >> > > I just discovered that -00 did not include some recent changes I had in my > tree, > aimed at prevent high latencies during fork pressure. I've committed -01 > which > does include them. When time allows, I'd be interested to know if this has > some > impact on the Ocotea figures. TIA,
bash-2.05b# cat /proc/ipipe/version 1.0-01 SWITCH without load: == Sampling period: 100 us RTH| lat min| lat avg| lat max| lost RTD| 5158| 5169| 10038| 0 iPipe 1.0-00 RTD| 5145| 5154| 10166| 0 iPipe 1.0-01 KLATENCY with load: RTH|-----lat min|-----lat avg|-----lat max|-overrun|----lat best|---lat worst RTS| 2953| 5974| 19147| 0| 00:12:05 1.0-00 RTS| 3035| 8705| 20705| 0| 00:09:54 1.0-01 LATENCY with load: == Sampling period: 100 us RTH|-----lat min|-----lat avg|-----lat max|-overrun|----lat best|---lat worst RTS| 3575| 7438| 24474| 0| 00:10:50 1.0-00 RTS| 3553| 10125| 23970| 0| 00:09:41 1.0-01 It has no significant impact, I think. Wolfgang.
