Going thru xenomai Kconfig again, some observations/uncertainties came up.
I'll make a patch, given feedback.
XENO_OPT_TIMING_PERIODIC
"Aperiodic mode provides for non-constant delays between timer ticks,"
the wording here (non-constant delays) left me momentarily wondering
if _APERIODIC was bad (this, despite the use of 'provides').
Maybe "sub-tick delays" makes some sense ..
XENO_OPT_SHIRQ_LEVEL
Are there any decent estimates or examples of the latency / jitter increases
if this is enabled ? Is it highly cpu or chipset dependent ?
I presume /proc/interrupts is the place to look to see if you might need it,
iff any of the devices of interest are shared.
my laptop shows sharing, my soekris does not
3: 5 XT-PIC ehci_hcd:usb1, ohci1394
4: 0 XT-PIC uhci_hcd:usb6
7: 708975 XT-PIC ipw2200, ehci_hcd:usb2, uhci_hcd:usb7
8: 1 XT-PIC rtc
9: 437509 XT-PIC acpi, Intel 82801DB-ICH4, Intel
82801DB-ICH4 Modem, ohci_hcd:usb3, ohci_hcd:usb4, uhci_hcd:usb5, yenta, eth0
# cat /proc/interrupts
CPU0
0: 13148086 XT-PIC timer
2: 0 XT-PIC cascade
4: 33084 XT-PIC serial
8: 4 XT-PIC rtc
10: 337134 XT-PIC eth0
11: 926639 XT-PIC ndiswrapper
14: 11 XT-PIC ide0
NMI: 0
XENO_OPT_SHIRQ_EDGE
does this only apply to ISA bus ?
XENO_SKIN_NATIVE
will add module name
XENO_OPT_NATIVE_INTR
Note that the preferred
way of implementing generic drivers usable across all Xenomai
interfaces is defined by the Real-Time Driver Model (RTDM).
It doesnt say theyre (in)?compatible, should it ?
SUMMARY
Id like to see estimates of the latency costs associated with each choice,
where its practical to do so (given the current unknowables, like
variations across
cpus, chipsets etc). I recognize that such numbers are the hoped-for
end result of the xenomai-data ML, and perhaps nothing real can be said
yet (or ever) in Kconfig, except in (overly?) broad statements.
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