1. No category

Technical Feasability Study:
Is Linux Ready for Medical Devices?
LinuxCon Europe 2014, Florian Mösch, Dräger Medical GmbH
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Who we are | What we did | What we learned
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Who we are | What we did | What we learned
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Who we are | What we did | What we learned
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Who we are | What we did | What we learned
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Who we are | What we did | What we learned
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Who we are | What we did | What we learned
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Who we are | What we did | What we learned
Safety, Security and Reliability
Cost & Licensing
Commercial Support
Boot Time Migration Effort Networking
Regulatory Aspects
Graphics Capabilities
Toolchain Quality
Future Proof
Realtime Scalability
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Who we are | What we did | What we learned
Windows Embedded Compact
Linux BSD Unix Neutrino
Free RTOS Pike OS Nucleus
Windows WOA
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Who we are | What we did | What we learned
vxWorks
Integrity
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Who we are | What we did | What we learned
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Who we are | What we did | What we learned
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Who we are | What we did | What we learned
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Who we are | What we did | What we learned
Linux
QNX
Comment
max. latency
?
25-125 µs depends on cpu allocation
max. CLC duration
?
100-460 µs depends on cpu allocation
measurements ran for just a few minutes
timing highly depends on cpu allocation (separate measurement + calculation threads)
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Who we are | What we did | What we learned
Realtime QA Farm
“cyclictest“ on
Freescale i.MX6
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Who we are | What we did | What we learned
void init() [
int fd = open("/sys/class/gpio/gpioXXX/direction", O_WRONLY);
write(fd, "in", 2);
close(fd);
fd = open("/sys/class/gpio/gpioXXX/edge", O_WRONLY);
write(fd, "falling", 7);
close(fd);
fd = open("/sys/class/gpio/gpioXXX/value", O_RDWR);
poll_fd = malloc(sizeof(*poll_fd));
poll_fd->fd = fd;
poll_fd->events = POLLPRI;
poll_fd->revents = 0;
}
void wait() {
char buf[2];
read(poll_fd->fd, buf, 1);
poll(poll_fd, 1, -1);
}
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Who we are | What we did | What we learned
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Who we are | What we did | What we learned
Linux
max. latency
max. CLC duration
H/W  S/W  H/W
QNX
Comment
66 µs
50 µs Linux: single core, QNX: two cores
250 µs
112 µs Linux: debug build, QNX: optimized
Linux
QNX
~10 µs
6.4 µs H/W trigger, S/W IRQ, GPIO out
Comment
Linux measurements ran for at least 12 hours
cheated: 100% „dummy“ load generated to avoid power-saving
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Who we are | What we did | What we learned
Linux
max. latency
max. CLC duration
QNX
Comment
66 µs
30 µs without graphics
250 µs
101 µs without graphics
max. latency
?!
>1000 µs with graphics (on separate core)
max. CLC duration
?!
>1000 µs with graphics (on separate core)
all measurements ran for at least 12 hours
cheated: 100% „dummy“ load generated to avoid power-saving
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Who we are | What we did | What we learned
Linux
max. latency
max. CLC duration
QNX
20 µs
30 µs Linux: kernel w/o graphics
280 µs
101 µs Linux: kernel w/o graphics
max. latency
34 µs
using system timer
max. CLC duration
63 µs
using system timer, max. optimization
max. latency
31 µs
using external trigger
253 µs
using external trigger
max. CLC duration
all measurements ran for at least 12 hours
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Comment
Who we are | What we did | What we learned
Linux
max. latency
max. CLC duration
QNX
vxWorks
Comment
31 µs
30 µs
55 µs no graphics used
253 µs
101 µs
214 µs no graphics used
all measurements ran for at least 12h
all systems using external trigger but not using graphics h/w
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Who we are | What we did | What we learned
Linux
max. latency
max. latency
?
31 µs
max. CLC duration
?
max. CLC duration
253 µs
QNX
>1000 µs
30 µs
>1000 µs
101 µs
all measurements ran for at least 12h
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Who we are | What we did | What we learned
vxWorks
?
Comment
with graphics load
55 µs w/o graphics load
?
with graphics load
214 µs w/o graphics load
Linux
QNX
vxWorks
?
max. latency
303 µs
971 µs
max. latency
31 µs
30 µs
max. CLC duration
> 6.500 µs
108 µs
?
max. CLC duration
253 µs
101 µs
214 µs w/o graphics load
Who we are | What we did | What we learned
with graphics load
55 µs w/o graphics load
all measurements ran for at least 12h
moderate graphics load on QNX, max. Load on Linux
no graphics support on vxWorks (yet)
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Comment
with graphics load
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Linux
QNX
max. latency
95 µs
65 µs
100 µs with graphics load
mean latency
3 µs
2 µs
15 µs with graphics load
max. latency
42 µs
47 µs
67 µs w/o graphics load
mean latency
1 µs
1 µs
10 µs w/o graphics load
max. CLC duration
161 µs
91 µs
171 µs with graphics load
mean CLC duration
21 µs
31 µs
86 µs with graphics load
max. CLC duration
76 µs
57 µs
109 µs w/o graphics load
mean CLC duration
19 µs
30 µs
63 µs w/o graphics load
Who we are | What we did | What we learned
vxWorks
Comment
Lessons Learned:
Never trust your Hardware
Compiler: Linux recent, QNX slightly behind, vxWorks – well...
Qt5: Linux recent, QNX slightly behind, vxWorks „early access“
Tracing: Linux: LTTng, QNX and vxWorks: commercial tools
User experience: „QNX feels a bit like Linux“
Users want to develop target S/W on Windows hosts.
Remote debugging: Eclipse (on Windows host...)
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Who we are | What we did | What we learned
Thanks to Thomas Mond and Roelof Berg
for their support.
Thank you
for your attention.