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15651201fa
If any scheduling-clock interrupt interrupts an RCU-preempt read-side critical section, the interrupted task's ->rcu_read_unlock_special.b.need_qs field is set. This causes the outermost rcu_read_unlock() to incur the extra overhead of calling into rcu_read_unlock_special(). This commit reduces that overhead by setting ->rcu_read_unlock_special.b.need_qs only if the grace period has been in effect for more than one second. Why one second? Because this is comfortably smaller than the minimum RCU CPU stall-warning timeout of three seconds, but long enough that the .need_qs marking should happen quite rarely. And if your RCU read-side critical section has run on-CPU for a full second, it is not unreasonable to invest some CPU time in ending the grace period quickly. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> |
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| .. | ||
| Kconfig | ||
| Kconfig.debug | ||
| Makefile | ||
| rcu_segcblist.c | ||
| rcu_segcblist.h | ||
| rcu.h | ||
| rcuperf.c | ||
| rcutorture.c | ||
| srcutiny.c | ||
| srcutree.c | ||
| sync.c | ||
| tiny.c | ||
| tree_exp.h | ||
| tree_plugin.h | ||
| tree.c | ||
| tree.h | ||
| update.c | ||