Hi all
This is my second try into implementing real-time futex
support. The patch below encloses a proposal on a way to do
real-time futexes that support priority-inheritance,
priority-protection, dead-owner recovery (similar to Sun's Robust
Mutex Extension) and dead lock detection, a sample implementation
(sans priority-protection) and a set of test programs along with a
very simple thread library to test it.
I have been working on this for a while, and got input from many
different people in different companies who are interested in
these features (eg: Intel, Cisco, Montavista, OSDL ...) We are
also working on a way to blend this into NPTL so it can do
real-time.
I'd love to hear feedback - specially on things where I just screwed
up big time and could be optimized really well.
Highlights:
- Currently on 2.5.64
- Does not modify original futexes - a new interface is added
Caveats:
- Timings are still a little bit crappy - looking into it.
- Priority protection not yet implemented.
- Many fixmes here and there that require answers
- Hook for properly acting when the priority of a waiting task is
changed not implemented yet.
- The tweak in timer.c is kind of ugly, and needs to be done much more
generic; maybe even moved into wake_up_process().
Check out kernel/rtfutex.c for a quick roadmap;
Documentation/rtfutex.txt for a longer series of rants and a something
more like a proposal or design
reference. Documentation/rtfutex-api.txt describes how to call the
functions.
Pointer to the test library:
http://sost.net/pub/linux/rtfutex-test-4.tar.bz2
Build with:
$ ./configure --with-headers=RTFUTEX-PATCHED-LINUX-TREE/include
$ make
Patch at: http://sost.net/pub/linux/rtfutex-4.patch
linux/Documentation/rtfutex-api.txt | 136
linux/Documentation/rtfutex.txt | 681 ++++
linux/include/asm-generic/futex.h | 64
linux/include/asm-i386/futex.h | 154 +
linux/include/linux/futex.h | 36
linux/include/linux/list.h | 2
linux/include/linux/plist.h | 163 +
linux/include/linux/sched.h | 12
linux/include/linux/vcache.h | 17
linux/kernel/Makefile | 2
linux/kernel/exit.c | 8
linux/kernel/fork.c | 13
linux/kernel/futex.c | 16
linux/kernel/rtfutex.c | 1663 +++++++++++
linux/kernel/sched.c | 30
linux/kernel/timer.c | 9
--Inaky Perez-Gonzalez -- Not speaking for Intel - opinions are my own [or my fault]
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This archive was generated by hypermail 2b29 : Sun Mar 23 2003 - 22:00:42 EST