2012/4/23 Gilles Chanteperdrix <[email protected]>: > On 04/23/2012 01:05 PM, Willy Lambert wrote: >> 2012/4/23 Philippe Gerum <[email protected]>: >>> On 04/23/2012 03:51 AM, Willy Lambert wrote: >>>> >>>> Hi, >>>> >>>> I have a message in dmesg about SMI workaround : >>>> Xenomai: SMI-enabled chipset found, but SMI workaround disabled >>>> (check CONFIG_XENO_HW_SMI_WORKAROUND). You may encounter >>>> high interrupt latencies! >>>> >>>> My kernel should be configured properly and following the "In case of >>>> high latencies" of >>>> http://www.xenomai.org/index.php/Configuring_x86_kernels thread, I did >>>> some tests. >>>> >>>> Latency test is here (if it is us it should be ok no ?): >>>> >>> >>> Yes, this looks ok, but you need to run this test longer, and try a few >>> usual suspects like plugging in/out USB devices while doing so (e.g. mouse, >>> netdev). >>> >>> The point of this message is to tell you that your chipset is known to >>> create latency issues in some cases (like most Intel chipset these days), >>> but you did not enable the Xenomai code which works around such issues by >>> shutting down problematic SMI sources. That may be right, or even required >>> to leave all the SMI sources enabled (e.g. thermal control), but this might >>> also lead to unacceptable latency spots. YMMV. >>> >>> This is basically a heads up message. >>> >>> -- >>> Philippe. >> >> Ok, thanks for answers. >> >> I did the test again , playing with usb and using the stress program >> to generate CPU load. The max latency for now is 15us in 4 mins. So I >> think it will be ok to keep SMI on for the time. Please let me know if >> this test is still stoo short. >> ^C---|-----------|-----------|-----------|--------|------|------------------------- >> RTS| 0.604| 2.332| 15.161| 0| 0| 00:03:59/00:03:59 >> >> Do you know by chance where I can found infos about SMI sources ? I >> suppose it is not in the ICH8M docs, it would be in my board doc ? Or >> have I a soft way to do this check so that I don't have to spend time >> with my vendor which will obviously have hard time to answer that ? > > The list of potential SMI sources IS in the ICH8M docs. Whether these > sources are used by your board essentially depends on the BIOS > implementation (an SMI traps into BIOS code). So the theoretical answer > to this question is to disassemble the the BIOS blob. >
ok, I think I won't do this for now as it's quite tricky, but I have the path in mind in case of problem. Thx for lighting up the way > The practical answer is to run latency during a few hours, under stress > using all the hardware which will be used in your target project > (network card, disk I/Os, USB key I/Os, etc...). If an SMI is used but > latencies remain acceptable with regard to your goals, no reason to bother. > > If you find unacceptable latencies, see the TROUBLESHOOTING guide, to > see how to enable SMI workaround. > > -- > Gilles. _______________________________________________ Xenomai-help mailing list [email protected] https://mail.gna.org/listinfo/xenomai-help
