* [Xenomai] How to locate the max latency @ 2018-07-03 8:59 Zheng, Qi 2018-07-04 7:27 ` Zheng, Qi 2018-07-05 6:02 ` Jan Kiszka 0 siblings, 2 replies; 7+ messages in thread From: Zheng, Qi @ 2018-07-03 8:59 UTC (permalink / raw) To: xenomai I am using xenomai 3.0.5 (https://xenomai.org/downloads/xenomai/stable/xenomai-3.0.5.tar.bz2) on the Intel SKL platform. On console mode or accessed by vnc viewer (no i915 graphics interrupt), the max latency values are usually below 20us no matter low or high loading (by stress-ng). But the max latency can reach up to 40us on GUI (gnome) mode (dozens of i915 interrupt counts per second). I tried enabling the ipipe trace function, but couldn't find valuable information. Is there any other good ways to locate the max latency? Or does anybody have experience on reducing the latency caused by graphics (such as i915) ? Many thanks. Best Regards SSG->OTC->One Linux Platform Engineering Team (Shanghai) ^ permalink raw reply [flat|nested] 7+ messages in thread
* [Xenomai] How to locate the max latency 2018-07-03 8:59 [Xenomai] How to locate the max latency Zheng, Qi @ 2018-07-04 7:27 ` Zheng, Qi 2018-07-04 11:10 ` Greg Gallagher 2018-07-05 6:02 ` Jan Kiszka 1 sibling, 1 reply; 7+ messages in thread From: Zheng, Qi @ 2018-07-04 7:27 UTC (permalink / raw) To: 'xenomai@xenomai.org' BTW, I already disabled the i915 power saving by adding "i915.enable_dc=0 i915.enable_rc6=0 i915.enable_execlists=0 i915.disable_power_well=0" in the cmdline. Best Regards SSG->OTC->One Linux Platform Engineering Team (Shanghai) From: Zheng, Qi Sent: Tuesday, July 3, 2018 5:00 PM To: xenomai@xenomai.org Subject: How to locate the max latency I am using xenomai 3.0.5 (https://xenomai.org/downloads/xenomai/stable/xenomai-3.0.5.tar.bz2) on the Intel SKL platform. On console mode or accessed by vnc viewer (no i915 graphics interrupt), the max latency values are usually below 20us no matter low or high loading (by stress-ng). But the max latency can reach up to 40us on GUI (gnome) mode (dozens of i915 interrupt counts per second). I tried enabling the ipipe trace function, but couldn't find valuable information. Is there any other good ways to locate the max latency? Or does anybody have experience on reducing the latency caused by graphics (such as i915) ? Many thanks. Best Regards SSG->OTC->One Linux Platform Engineering Team (Shanghai) ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [Xenomai] How to locate the max latency 2018-07-04 7:27 ` Zheng, Qi @ 2018-07-04 11:10 ` Greg Gallagher 2018-07-05 0:29 ` Zheng, Qi 0 siblings, 1 reply; 7+ messages in thread From: Greg Gallagher @ 2018-07-04 11:10 UTC (permalink / raw) To: Zheng, Qi, xenomai Did youale any changes in menuconfig when building the kernel? Greg Original Message From: qi.zheng@intel.com Sent: July 4, 2018 3:27 AM To: xenomai@xenomai.org Subject: [Xenomai] How to locate the max latency BTW, I already disabled the i915 power saving by adding "i915.enable_dc=0 i915.enable_rc6=0 i915.enable_execlists=0 i915.disable_power_well=0" in the cmdline. Best Regards SSG->OTC->One Linux Platform Engineering Team (Shanghai) From: Zheng, Qi Sent: Tuesday, July 3, 2018 5:00 PM To: xenomai@xenomai.org Subject: How to locate the max latency I am using xenomai 3.0.5 (https://xenomai.org/downloads/xenomai/stable/xenomai-3.0.5.tar.bz2) on the Intel SKL platform. On console mode or accessed by vnc viewer (no i915 graphics interrupt), the max latency values are usually below 20us no matter low or high loading (by stress-ng). But the max latency can reach up to 40us on GUI (gnome) mode (dozens of i915 interrupt counts per second). I tried enabling the ipipe trace function, but couldn't find valuable information. Is there any other good ways to locate the max latency? Or does anybody have experience on reducing the latency caused by graphics (such as i915) ? Many thanks. Best Regards SSG->OTC->One Linux Platform Engineering Team (Shanghai) _______________________________________________ Xenomai mailing list Xenomai@xenomai.org https://xenomai.org/mailman/listinfo/xenomai ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [Xenomai] How to locate the max latency 2018-07-04 11:10 ` Greg Gallagher @ 2018-07-05 0:29 ` Zheng, Qi 0 siblings, 0 replies; 7+ messages in thread From: Zheng, Qi @ 2018-07-05 0:29 UTC (permalink / raw) To: Greg Gallagher, xenomai Yes, most of my modifications on top of general x86_64 config were based on the https://gitlab.denx.de/Xenomai/xenomai/wikis/Configuring_For_X86_Based_Dual_Kernels. Besides, I enabled the "CONFIG_PREEMPT", gained a little bit latency improvement by my test. And I also confirmed there was no SMI during the test. Best Regards SSG->OTC->One Linux Platform Engineering Team (Shanghai) -----Original Message----- From: Greg Gallagher [mailto:greg@embeddedgreg.com] Sent: Wednesday, July 4, 2018 7:11 PM To: Zheng, Qi <qi.zheng@intel.com>; xenomai@xenomai.org Subject: Re: [Xenomai] How to locate the max latency Did youale any changes in menuconfig when building the kernel? Greg Original Message From: qi.zheng@intel.com Sent: July 4, 2018 3:27 AM To: xenomai@xenomai.org Subject: [Xenomai] How to locate the max latency BTW, I already disabled the i915 power saving by adding "i915.enable_dc=0 i915.enable_rc6=0 i915.enable_execlists=0 i915.disable_power_well=0" in the cmdline. Best Regards SSG->OTC->One Linux Platform Engineering Team (Shanghai) From: Zheng, Qi Sent: Tuesday, July 3, 2018 5:00 PM To: xenomai@xenomai.org Subject: How to locate the max latency I am using xenomai 3.0.5 (https://xenomai.org/downloads/xenomai/stable/xenomai-3.0.5.tar.bz2) on the Intel SKL platform. On console mode or accessed by vnc viewer (no i915 graphics interrupt), the max latency values are usually below 20us no matter low or high loading (by stress-ng). But the max latency can reach up to 40us on GUI (gnome) mode (dozens of i915 interrupt counts per second). I tried enabling the ipipe trace function, but couldn't find valuable information. Is there any other good ways to locate the max latency? Or does anybody have experience on reducing the latency caused by graphics (such as i915) ? Many thanks. Best Regards SSG->OTC->One Linux Platform Engineering Team (Shanghai) _______________________________________________ Xenomai mailing list Xenomai@xenomai.org https://xenomai.org/mailman/listinfo/xenomai ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [Xenomai] How to locate the max latency 2018-07-03 8:59 [Xenomai] How to locate the max latency Zheng, Qi 2018-07-04 7:27 ` Zheng, Qi @ 2018-07-05 6:02 ` Jan Kiszka 2018-07-05 6:55 ` Zheng, Qi 1 sibling, 1 reply; 7+ messages in thread From: Jan Kiszka @ 2018-07-05 6:02 UTC (permalink / raw) To: Zheng, Qi, xenomai On 2018-07-03 10:59, Zheng, Qi wrote: > I am using xenomai 3.0.5 (https://xenomai.org/downloads/xenomai/stable/xenomai-3.0.5.tar.bz2) on the Intel SKL platform. > On console mode or accessed by vnc viewer (no i915 graphics interrupt), the max latency values are usually below 20us no matter low or high loading (by stress-ng). > But the max latency can reach up to 40us on GUI (gnome) mode (dozens of i915 interrupt counts per second). > I tried enabling the ipipe trace function, but couldn't find valuable information. > Is there any other good ways to locate the max latency? > Or does anybody have experience on reducing the latency caused by graphics (such as i915) ? > Many thanks. > First of all, how long did you run the tests? Maybe enabling graphics just increases the probability to hit the peak, and the same is conceptually possible without it. It may also be the case that this is hardware-induced (GPU). Do you see a similar increase in the latency (even if from a different ground level) when using the PREEMPT-RT kernel? Jan -- Siemens AG, Corporate Technology, CT RDA IOT SES-DE Corporate Competence Center Embedded Linux ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [Xenomai] How to locate the max latency 2018-07-05 6:02 ` Jan Kiszka @ 2018-07-05 6:55 ` Zheng, Qi 2018-07-05 6:59 ` Jan Kiszka 0 siblings, 1 reply; 7+ messages in thread From: Zheng, Qi @ 2018-07-05 6:55 UTC (permalink / raw) To: Jan Kiszka, xenomai 1. I run the test one hour for a round, totally tested for 12 rounds. The data were consistent, on console mode, max latency were between 10us to 19us, on GUI mode, they were between 28us to 42us. 2. I tried the PREEMPT-RT kernel, yes, there was similar increase. Best Regards SSG->OTC->One Linux Platform Engineering Team (Shanghai) -----Original Message----- From: Jan Kiszka [mailto:jan.kiszka@siemens.com] Sent: Thursday, July 5, 2018 2:02 PM To: Zheng, Qi <qi.zheng@intel.com>; xenomai@xenomai.org Subject: Re: How to locate the max latency On 2018-07-03 10:59, Zheng, Qi wrote: > I am using xenomai 3.0.5 (https://xenomai.org/downloads/xenomai/stable/xenomai-3.0.5.tar.bz2) on the Intel SKL platform. > On console mode or accessed by vnc viewer (no i915 graphics interrupt), the max latency values are usually below 20us no matter low or high loading (by stress-ng). > But the max latency can reach up to 40us on GUI (gnome) mode (dozens of i915 interrupt counts per second). > I tried enabling the ipipe trace function, but couldn't find valuable information. > Is there any other good ways to locate the max latency? > Or does anybody have experience on reducing the latency caused by graphics (such as i915) ? > Many thanks. > First of all, how long did you run the tests? Maybe enabling graphics just increases the probability to hit the peak, and the same is conceptually possible without it. It may also be the case that this is hardware-induced (GPU). Do you see a similar increase in the latency (even if from a different ground level) when using the PREEMPT-RT kernel? Jan -- Siemens AG, Corporate Technology, CT RDA IOT SES-DE Corporate Competence Center Embedded Linux ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [Xenomai] How to locate the max latency 2018-07-05 6:55 ` Zheng, Qi @ 2018-07-05 6:59 ` Jan Kiszka 0 siblings, 0 replies; 7+ messages in thread From: Jan Kiszka @ 2018-07-05 6:59 UTC (permalink / raw) To: Zheng, Qi, xenomai On 2018-07-05 08:55, Zheng, Qi wrote: > 1. I run the test one hour for a round, totally tested for 12 rounds. > The data were consistent, on console mode, max latency were between 10us to 19us, on GUI mode, they were between 28us to 42us. > 2. I tried the PREEMPT-RT kernel, yes, there was similar increase. > Then you should probably discuss this with your colleagues from the hardware design, if there are ways for software to avoid that increase at all. If there are, we can look for how they can be activated on Linux (but we likely need some hints from them). Jan > > Best Regards > > SSG->OTC->One Linux Platform Engineering Team (Shanghai) > > > -----Original Message----- > From: Jan Kiszka [mailto:jan.kiszka@siemens.com] > Sent: Thursday, July 5, 2018 2:02 PM > To: Zheng, Qi <qi.zheng@intel.com>; xenomai@xenomai.org > Subject: Re: How to locate the max latency > > On 2018-07-03 10:59, Zheng, Qi wrote: >> I am using xenomai 3.0.5 (https://xenomai.org/downloads/xenomai/stable/xenomai-3.0.5.tar.bz2) on the Intel SKL platform. >> On console mode or accessed by vnc viewer (no i915 graphics interrupt), the max latency values are usually below 20us no matter low or high loading (by stress-ng). >> But the max latency can reach up to 40us on GUI (gnome) mode (dozens of i915 interrupt counts per second). >> I tried enabling the ipipe trace function, but couldn't find valuable information. >> Is there any other good ways to locate the max latency? >> Or does anybody have experience on reducing the latency caused by graphics (such as i915) ? >> Many thanks. >> > First of all, how long did you run the tests? Maybe enabling graphics just increases the probability to hit the peak, and the same is conceptually possible without it. > > It may also be the case that this is hardware-induced (GPU). Do you see a similar increase in the latency (even if from a different ground > level) when using the PREEMPT-RT kernel? > > 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 ^ permalink raw reply [flat|nested] 7+ messages in thread
end of thread, other threads:[~2018-07-05 6:59 UTC | newest] Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2018-07-03 8:59 [Xenomai] How to locate the max latency Zheng, Qi 2018-07-04 7:27 ` Zheng, Qi 2018-07-04 11:10 ` Greg Gallagher 2018-07-05 0:29 ` Zheng, Qi 2018-07-05 6:02 ` Jan Kiszka 2018-07-05 6:55 ` Zheng, Qi 2018-07-05 6:59 ` Jan Kiszka
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