|| ||Ingo Molnar <email@example.com>|
|| ||[patch] Real-Time Preemption, -RT-2.6.13-rc4-V0.7.53-01, High Resolution Timers & RCU-tasklist features|
|| ||Thu, 11 Aug 2005 13:00:51 +0200|
|| ||Thomas Gleixner <firstname.lastname@example.org>,
"Paul E. McKenney" <email@example.com>,
george anzinger <firstname.lastname@example.org>|
i have released the -53-01 Real-Time Preemption patch, which can be
there are two new features in this release, which justified the jump
from .52 to .53:
- the inclusion of the High Resolution Timers patch, written by
George Anzinger, and ported/improved/cleaned-up by Thomas Gleixner.
- the inclusion of the RCU tasklist_lock patch from Paul McKenney.
the HRT patch from George Anzinger is a crutial piece of real-time
infrastructure. The version included in the -RT tree supports both PIT
and local APIC timer driven variable-rate timer interrupts.
Thomas Glexiner, besides porting it to PREEMPT_RT, cleaning it up,
adding the local APIC timer support has also added the
CONFIG_HIGH_RES_TIMERS_DYN_PRIO feature, which pushes priority
inheritance into the high-res timer space. Furthermore, Thomas has
extended nanosleep to use HR timers, if the task is RT. This makes it
easier to test HRT functionality.
NOTE: there's a new softirq, softirq-hrtimer (PID 8 on UP x86), which
should be chrt-ed to higher than SCHED_FIFO-50 if HR timer interrupts
are the most important latencies in the system. E.g.:
chrt -f 90 -p 8
the RCU tasklist-lock patch is a small but important feature from Paul
McKenney which enables good HRT latencies: the HRT patch, when using
POSIX timers, would use a signal-sending codepath that depends on the
tasklist_lock, and thus the (quite high) tasklist_lock latencies
controlled the latency of HR timers - defeating much of the benefits of
HR timers. With the RCU tasklist-lock the signal sending path is now
RCU-read locked, with no locking dependency, and thus excellent
given these changes, some (mostly build-related) regressions are to be
expected. Only the x86 architecture is expected to work for now.
to build a -V0.7.53-01 tree, the following patches should to be applied:
patches, bugreports and any other feedback welcome,
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