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author | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2016-11-30 06:24:30 -0800 |
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committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2017-10-09 14:25:17 -0700 |
commit | f79c3ad6189624c3de0ad5521610c9e22a1c33cf (patch) | |
tree | 82bfe610ef11d2dbaf120f7ddbbc250ec4f917fb /arch/um/kernel/vmlinux.lds.S | |
parent | 8a5776a5f49812d29fe4b2d0a2d71675c3facf3f (diff) | |
download | op-kernel-dev-f79c3ad6189624c3de0ad5521610c9e22a1c33cf.zip op-kernel-dev-f79c3ad6189624c3de0ad5521610c9e22a1c33cf.tar.gz |
sched,rcu: Make cond_resched() provide RCU quiescent state
There is some confusion as to which of cond_resched() or
cond_resched_rcu_qs() should be added to long in-kernel loops.
This commit therefore eliminates the decision by adding RCU quiescent
states to cond_resched(). This commit also simplifies the code that
used to interact with cond_resched_rcu_qs(), and that now interacts with
cond_resched(), to reduce its overhead. This reduction is necessary to
allow the heavier-weight cond_resched_rcu_qs() mechanism to be invoked
everywhere that cond_resched() is invoked.
Part of that reduction in overhead converts the jiffies_till_sched_qs
kernel parameter to read-only at runtime, thus eliminating the need for
bounds checking.
Reported-by: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
[ paulmck: Keep PREEMPT=n cond_resched a no-op, per Peter Zijlstra. ]
Diffstat (limited to 'arch/um/kernel/vmlinux.lds.S')
0 files changed, 0 insertions, 0 deletions