rcu: Reduce expedited GP memory contention via per-CPU variables

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Currently, the piggybacked-work checks carried out by sync_exp_work_done()
atomically increment a small set of variables (the ->expedited_workdone0,
->expedited_workdone1, ->expedited_workdone2, ->expedited_workdone3
fields in the rcu_state structure), which will form a memory-contention
bottleneck given a sufficiently large number of CPUs concurrently invoking
either synchronize_rcu_expedited() or synchronize_sched_expedited().

This commit therefore moves these for fields to the per-CPU rcu_data
structure, eliminating the memory contention.  The show_rcuexp() function
also changes to sum up each field in the rcu_data structures.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

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This commit is contained in:

Paul E. McKenney 2015-10-01 10:26:24 -07:00

parent 1307f21487

commit df5bd5144a

3 changed files with 21 additions and 16 deletions

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11

kernel/rcu/tree.c

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8

kernel/rcu/tree.h

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16

kernel/rcu/tree_trace.c

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