Re: [Xenomai] tsc not monotonic

["Vincent Berenz" <vincent.berenz@tuebingen.mpg.de>]

Hi,

Many thanks for the answer.

We use new hardware. I am working on a recent dell precision T7910. I did not try to update our older hardware (still in use).

Info on the CPU of the new machine:

-----
processor	: 23
vendor_id	: GenuineIntel
cpu family	: 6
model		: 63
model name	: Intel(R) Xeon(R) CPU E5-2690 v3 @ 2.60GHz
stepping	: 2
microcode	: 0x36
cpu MHz		: 2594.037
cache size	: 30720 KB
physical id	: 1
siblings	: 12
core id		: 13
cpu cores	: 12
apicid		: 58
initial apicid	: 58
fpu		: yes
fpu_exception	: yes
cpuid level	: 15
wp		: yes
flags		: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx pdpe1gb rdtscp lm constant_tsc arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc aperfmperf pni pclmulqdq dtes64 monitor ds_cpl vmx smx est tm2 ssse3 fma cx16 xtpr pdcm pcid dca sse4_1 sse4_2 x2apic movbe popcnt tsc_deadline_timer aes xsave avx f16c rdrand lahf_lm abm ida arat epb xsaveopt pln pts dtherm tpr_shadow vnmi flexpriority ept vpid fsgsbase tsc_adjust bmi1 avx2 smep bmi2 erms invpcid
bogomips	: 5189.70
clflush size	: 64
cache_alignment	: 64
address sizes	: 46 bits physical, 48 bits virtual
power management:
-----

There are 24 processors and I had to update the config file:

---
CONFIG_XENO_OPT_PIPE_NRDEV=32
CONFIG_XENO_OPT_REGISTRY_NRSLOTS=1024
CONFIG_XENO_OPT_SYS_HEAPSZ=32768
CONFIG_XENO_OPT_SYS_STACKPOOLSZ=4096
---

Best

Vincent

On Thu, 4 Aug 2016 14:17:44 +0200
 Henning Schild <henning.schild@siemens.com> wrote:
> Am Wed, 3 Aug 2016 12:12:51 +0200
> schrieb Vincent Berenz <vincent.berenz@tuebingen.mpg.de>:
> 
> > Hi,
> > 
> > After using for years xenomai 2.5.6 on ubuntu 12.04, we decided to
> > upgrade to ubuntu 14.04 and a newer machine. I installed xenomai
> > 2.6.4 and kernel 3.14.39. The installation boots correctly, the
> > latency is low and our software seems to work ok.
> > 
> > But the system has "frequency surge" (I could not find better
> > wording). For example:
> > 
> > - sometime when typing on the keyboard, the pressed key is printed
> > many times ('aaaaaaaa' instead of 'a')
> > 
> > - 'glxgears' has change in frame rates, the gears can be seen as
> > sometime changing speed. For example:
> > 
> > ---
> > 1141 frames in 5.0 seconds = 228.186 FPS
> > 1024 frames in 5.0 seconds = 204.787 FPS
> > 506 frames in 5.0 seconds = 101.194 FPS
> > 482 frames in 5.0 seconds = 96.317 FPS
> > 1416 frames in 5.0 seconds = 283.182 FPS
> > 2614 frames in 5.0 seconds = 521.100 FPS
> > 2618 frames in 5.0 seconds = 522.314 FPS
> > 3073 frames in 5.0 seconds = 614.562 FPS
> > ---
> > 
> > All the tests run fine (as far as I could tell) with the notable
> > exception of tsc which sometimes (not always) terminates with
> > something like:
> > 
> > ---
> > tsc not monotonic after 7430687798 ticks, jumped back 49567650 tick
> > ---
> > 
> > I could find this in the syslog:
> > 
> > -------
> > [    0.092932] TSC deadline timer enabled
> > [    0.092941] Performance Events: PEBS fmt2+, 16-deep LBR, Haswell
> > events, full-width counters, Intel PMU driver. [    0.092961] ...
> > version:                3 [    0.092962] ... bit width:
> > 48 [    0.092963] ... generic registers:      4
> > [    0.092964] ... value mask:             0000ffffffffffff
> > [    0.092965] ... max period:             0000ffffffffffff
> > [    0.092965] ... fixed-purpose events:   3
> > [    0.092966] ... event mask:             000000070000000f
> > [    0.094914] x86: Booting SMP configuration:
> > [    0.094916] .... node  #0, CPUs:        #1
> > [    0.109150] TSC synchronization [CPU#0 -> CPU#1]:
> > [    0.109157] Measured 25802382 cycles TSC warp between CPUs,
> > turning off TSC clock. [    0.109161] tsc: Marking TSC unstable due
> > to check_tsc_sync_source failed ---------
> 
> I have seen this message before, but with smaller numbers.
> 
> I assume you have not changed the Hardware, which versions of Xenomai
> and the Kernel did you use before? Trying to find out whether these
> checks did not trigger before because they did not exist or where
> different in your old setup.
> 
> > Best
> > 
> > Vincent
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