|| ||Ingo Molnar <firstname.lastname@example.org>|
|| ||[patch] Real-Time Preemption, -RT-2.6.9-mm1-V0|
|| ||Mon, 25 Oct 2004 12:40:23 +0200|
|| ||Lee Revell <email@example.com>,
Rui Nuno Capela <firstname.lastname@example.org>,
Mark_H_Johnson@Raytheon.com, "K.R. Foley" <email@example.com>,
Bill Huey <firstname.lastname@example.org>, Adam Heath <email@example.com>,
Florian Schmidt <firstname.lastname@example.org>,
Thomas Gleixner <email@example.com>,
Michal Schmidt <firstname.lastname@example.org>,
Fernando Pablo Lopez-Lezcano <nando@ccrma.Stanford.EDU>,
Alexander Batyrshin <email@example.com>|
i have released the -V0 Real-Time Preemption patch, which can be
NOTE: this is a highly experimental release, a more experimental one
the big change in the '-V' series of the patchset is that i have
converted the last couple of non-preemptible kernel subsystems to
fully-preemptible mutex-based locking. These subsystems are:
- the SLAB allocator
- the buddy page allocator
- waitqueue handling
- soft-timer subsystem
- the random driver
this is probably the last 'big leap forward' in terms of the scope of
the patch. (having reached the ultimate scope: it now encompasses
But as an inevitable result of this big leap it will likely break in a
couple of places. Unfortunately these subsystems were largely
interdependent so it's an all-or-nothing step with not much middle
ground between the locking done in -U10.3 and in -V0.
another result of these changes is that the number of critical sections
in -V0 is roughly 30% of that in -U10.3. Now we only have the scheduler
and very lowlevel IRQ-hardware locks as raw spinlocks. (plus the lone
holdout vga_lock - which i will probably make a mutex too in the near
[ NOTE: there's one known bug in this release: selinux on one of my
testsystems broke, it hangs during bootup. With CONFIG_SECURITY disabled
it works fine. I'm working on the fix. So please keep CONFIG_SECURITY
disabled for the time being. ]
other changes in -V0:
- build fixes: more driver fixes from Thomas Gleixner
- crash fix: fixed a bug found by Thomas Gleixner: rwsem runtime
initialization was racy.
- deadlock fix: fixed lockup bug caused by __schedule clearing
PREEMPT_ACTIVE. The need_resched loop is now outside of __schedule().
This might solve lockups/slowdowns reported by some people.
- latency fix: made keventd SCHED_FIFO - this could fix the mouse
related delays reported by a number of people.
- latency fix: fixed SMP lock-break mechanism of mutexes.
- usability feature: hard-interrupts get decreasing SCHED_FIFO priority
starting at prio 49 and stopping at prio 25. This should give a good
- debug feature: implemented SysRq-D to show the list of tasks with
locks blocked on, if RW_SEM_DEADLOCK_DETECTION is enabled.
to create a -V0 tree from scratch, the patching order is:
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