Re: [(RT RFC) PATCH v2 2/9] sysctl for runtime-control of lateral mutex stealing
From: Pavel Machek <hidden>
Date: 2008-02-25 21:53:23
Also in:
lkml
Hi!
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From: Sven-Thorsten Dietrich <redacted> Add /proc/sys/kernel/lateral_steal, to allow switching on and off equal-priority mutex stealing between threads. Signed-off-by: Sven-Thorsten Dietrich <redacted> --- kernel/rtmutex.c | 7 ++++++- kernel/sysctl.c | 14 ++++++++++++++ 2 files changed, 20 insertions(+), 1 deletions(-)diff --git a/kernel/rtmutex.c b/kernel/rtmutex.c index 6624c66..cd39c26 100644 --- a/kernel/rtmutex.c +++ b/kernel/rtmutex.c@@ -18,6 +18,10 @@ #include "rtmutex_common.h" +#ifdef CONFIG_RTLOCK_LATERAL_STEAL +int rtmutex_lateral_steal __read_mostly = 1; +#endif +
Ugly..
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/* * lock->owner state tracking: *@@ -321,7 +325,8 @@ static inline int lock_is_stealable(struct task_struct *pendowner, int unfair) if (current->prio > pendowner->prio) return 0; - if (!unfair && (current->prio == pendowner->prio)) + if (unlikely(current->prio == pendowner->prio) && + !(unfair && rtmutex_lateral_steal)) #endif
But this is even worse, you are creating #ifdef maze here. Can you simply #define rtmutex_lateral_steal 0 in !CONFIG_RTLOCK_LATERAL_STEAL and let the optimizer fix this?
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index c913d48..c24c53d 100644--- a/kernel/sysctl.c +++ b/kernel/sysctl.c@@ -175,6 +175,10 @@ extern struct ctl_table inotify_table[]; int sysctl_legacy_va_layout; #endif +#ifdef CONFIG_RTLOCK_LATERAL_STEAL +extern int rtmutex_lateral_steal; +#endif +
Try checkpatch. Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html