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| author | Paul E. McKenney <paul.mckenney@linaro.org> | 2011-11-22 20:43:02 -0800 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2011-12-11 10:32:02 -0800 |
| commit | f535a607c13c7b674e0788ca5765779aa74a01c3 (patch) | |
| tree | 433a07d16ff11d9f67e7991831cebf3cadfd9939 /include/trace | |
| parent | 84ad00cb61f1cb21f0b63bc6f7dc254399eb3830 (diff) | |
| download | linux-f535a607c13c7b674e0788ca5765779aa74a01c3.tar.bz2 | |
rcu: Eliminate RCU_FAST_NO_HZ grace-period hang
With the new implementation of RCU_FAST_NO_HZ, it was possible to hang
RCU grace periods as follows:
o CPU 0 attempts to go idle, cycles several times through the
rcu_prepare_for_idle() loop, then goes dyntick-idle when
RCU needs nothing more from it, while still having at least
on RCU callback pending.
o CPU 1 goes idle with no callbacks.
Both CPUs can then stay in dyntick-idle mode indefinitely, preventing
the RCU grace period from ever completing, possibly hanging the system.
This commit therefore prevents CPUs that have RCU callbacks from entering
dyntick-idle mode. This approach also eliminates the need for the
end-of-grace-period IPIs used previously.
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Diffstat (limited to 'include/trace')
| -rw-r--r-- | include/trace/events/rcu.h | 1 |
1 files changed, 0 insertions, 1 deletions
diff --git a/include/trace/events/rcu.h b/include/trace/events/rcu.h index debe453c9623..8dd6fcb94946 100644 --- a/include/trace/events/rcu.h +++ b/include/trace/events/rcu.h @@ -287,7 +287,6 @@ TRACE_EVENT(rcu_dyntick, * * "No callbacks": Nothing to do, no callbacks on this CPU. * "In holdoff": Nothing to do, holding off after unsuccessful attempt. - * "Dyntick with callbacks": Callbacks remain, but RCU doesn't need CPU. * "Begin holdoff": Attempt failed, don't retry until next jiffy. * "More callbacks": Still more callbacks, try again to clear them out. * "Callbacks drained": All callbacks processed, off to dyntick idle! |