Dear Jan: For the graphic thing, our system really needs graphic, it could not be removed. Otherwise, I saw articles that someone got very low latency also in some X86 ubuntu-desktop version, so I wonder whether the graphic is the key factor to the realtime system. For your second point: "Try that with a vanilla kernel on your hardware." You mean I can use the hardware latency detector to test my kernel?
-------------------------------- Best regards Kevin ----- 原始邮件 ----- 发件人：Jan Kiszka <[email protected]> 收件人：[email protected], xenomai <[email protected]> 主题：Re: 回复：Re: 回复：Re: Xenomai latency_test_not_good 日期：2019年09月09日 20点34分 On 09.09.19 13:48, 鲁克文 wrote: > Dear Jan Kiszka > > Thanks for your reply. > And I add "idle=poll" to the kernel parameter, but it results no help;and I > enter the BIOS setup window and disable some ACPI setting,also no help. > > For the latency test:(1)when system is startup, and just run latency test, > the > latency is not very large, just about 13 micro-second;(2) when I run latency > test, and then start Firefox to do some web-browsing, as access website like: > www.sina.com.cn, the latency suddenly goes higher as hundreds of > mirco-second. I > wonder whether this phenomenon could help us. > You mean that you have a graphic desktop running? Try without that. GPUs may cause hardware-related latencies as well. > Also, for the SMI thing, could I just use msr-tools to verify that the > realtime > system is really influenced by the SMI thing? > The mainline kernel has the Hardware Latency Detector (see linux/Documentation/trace/hwlat_detector.rst). Try that with a vanilla kernel on your hardware. Jan > > -------------------------------- > > Best regards > Kevin > > ----- 原始邮件 ----- > 发件人：Jan Kiszka <[email protected]> > 收件人：[email protected], xenomai <[email protected]> > 主题：Re: 回复：Re: Xenomai latency test not good > 日期：2019年09月09日 19点19分 > > > On 09.09.19 12:14, 鲁克文 wrote: > > Dear Jan Kiszka: > > > > I re-enable ACPI_PROCESSOR in the kernel, but also the latency test seems > no > > good,attached file is the new kernel config file. > > > > > /*********************************************************************************************/ > > RTT| 00:01:04 (periodic user-mode task, 100 us period, priority 99) > > RTH|----lat min|----lat avg|----lat max|-overrun|---msw|---lat best|--lat > worst > > RTD| 0.072| 0.785| 19.712| 2| 0| -0.177| > 131.284 > > RTD| 0.096| 2.280| 15.701| 2| 0| -0.177| > 131.284 > > RTD| 0.059| 1.573| 12.868| 2| 0| -0.177| > 131.284 > > RTD| 0.058| 2.512| 25.545| 2| 0| -0.177| > 131.284 > > RTD| 0.286| 1.928| 153.611| 3| 0| -0.177| > 153.611 > > RTD| 0.285| 2.834| 17.032| 3| 0| -0.177| > 153.611 > > RTD| 0.128| 2.104| 26.467| 3| 0| -0.177| > 153.611 > > RTD| 0.140| 1.105| 14.978| 3| 0| -0.177| > 153.611 > > RTD| 0.163| 0.950| 12.708| 3| 0| -0.177| > 153.611 > > RTD| 0.199| 1.012| 15.109| 3| 0| -0.177| > 153.611 > > RTD| 0.042| 1.007| 10.511| 3| 0| -0.177| > 153.611 > > RTD| 0.102| 0.763| 125.684| 4| 0| -0.177| > 153.611 > > RTD| 0.138| 0.810| 12.226| 4| 0| -0.177| > 153.611 > > RTD| 0.125| 1.312| 13.858| 4| 0| -0.177| > 153.611 > > RTD| 0.256| 0.854| 67.039| 4| 0| -0.177| > 153.611 > > RTD| 0.280| 0.841| 14.205| 4| 0| -0.177| > 153.611 > > RTD| 0.099| 0.631| 76.185| 4| 0| -0.177| > 153.611 > > RTD| 0.230| 0.953| 16.041| 4| 0| -0.177| > 153.611 > > RTD| 0.086| 0.985| 65.416| 4| 0| -0.177| > 153.611 > > RTD| 0.110| 0.856| 18.357| 4| 0| -0.177| > 153.611 > > > /************************************************************************************/ > > > Yeah, these numbers are still off. Likely, we see some power management > effects. > They might be triggered by Linux, and then some kernel switch can do the magic > (check e.g. CONFIG_ACPI_PROCESSOR_CSTATE). You may also try "idle=poll" as > kernel parameter. Or the issue is caused by the firmware (bios). Check power > settings there. In the worst case, the behaviour is SMI induced and can't be > disabled. Then only a different firmware can help - or a different hardware. > Jan > -- > Siemens AG, Corporate Technology, CT RDA IOT SES-DE > Corporate Competence Center Embedded Linux -- Siemens AG, Corporate Technology, CT RDA IOT SES-DE Corporate Competence Center Embedded Linux
