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| author | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2015-04-20 19:27:15 +0200 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2015-05-27 21:59:04 +0200 |
| commit | 7fa270010e0ddd3693381431f373b3e3135b0695 (patch) | |
| tree | 896b3eaa0bbc48b80ca45b4e01711699e7e1199f /kernel/rcu | |
| parent | rcu: Directly drive RCU_USER_QS from Kconfig (diff) | |
| download | linux-7fa270010e0ddd3693381431f373b3e3135b0695.tar.xz linux-7fa270010e0ddd3693381431f373b3e3135b0695.zip | |
rcu: Convert CONFIG_RCU_FANOUT_EXACT to boot parameter
The CONFIG_RCU_FANOUT_EXACT Kconfig parameter is used primarily (and
perhaps only) by rcutorture to verify that RCU works correctly in specific
rcu_node combining-tree configurations. It therefore does not make
much sense have this as a question to people attempting to configure
their kernels. So this commit creates an rcutree.rcu_fanout_exact=
boot parameter that rcutorture can use, and eliminates the original
CONFIG_RCU_FANOUT_EXACT Kconfig parameter.
Reported-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Pranith Kumar <bobby.prani@gmail.com>
Diffstat (limited to 'kernel/rcu')
| -rw-r--r-- | kernel/rcu/tree.c | 7 | ||||
| -rw-r--r-- | kernel/rcu/tree_plugin.h | 2 |
2 files changed, 6 insertions, 3 deletions
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 2f3cb5513ca3..b49c474e1fff 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -113,6 +113,9 @@ RCU_STATE_INITIALIZER(rcu_bh, 'b', call_rcu_bh); static struct rcu_state *rcu_state_p; LIST_HEAD(rcu_struct_flavors); +/* Control rcu_node-tree auto-balancing at boot time. */ +static bool rcu_fanout_exact; +module_param(rcu_fanout_exact, bool, 0444); /* Increase (but not decrease) the CONFIG_RCU_FANOUT_LEAF at boot time. */ static int rcu_fanout_leaf = CONFIG_RCU_FANOUT_LEAF; module_param(rcu_fanout_leaf, int, 0444); @@ -3956,13 +3959,13 @@ void rcu_scheduler_starting(void) /* * Compute the per-level fanout, either using the exact fanout specified - * or balancing the tree, depending on CONFIG_RCU_FANOUT_EXACT. + * or balancing the tree, depending on the rcu_fanout_exact boot parameter. */ static void __init rcu_init_levelspread(struct rcu_state *rsp) { int i; - if (IS_ENABLED(CONFIG_RCU_FANOUT_EXACT)) { + if (rcu_fanout_exact) { rsp->levelspread[rcu_num_lvls - 1] = rcu_fanout_leaf; for (i = rcu_num_lvls - 2; i >= 0; i--) rsp->levelspread[i] = CONFIG_RCU_FANOUT; diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h index 58b1ebdc4387..eb460ec747ef 100644 --- a/kernel/rcu/tree_plugin.h +++ b/kernel/rcu/tree_plugin.h @@ -64,7 +64,7 @@ static void __init rcu_bootup_announce_oddness(void) (!IS_ENABLED(CONFIG_64BIT) && CONFIG_RCU_FANOUT != 32)) pr_info("\tCONFIG_RCU_FANOUT set to non-default value of %d\n", CONFIG_RCU_FANOUT); - if (IS_ENABLED(CONFIG_RCU_FANOUT_EXACT)) + if (rcu_fanout_exact) pr_info("\tHierarchical RCU autobalancing is disabled.\n"); if (IS_ENABLED(CONFIG_RCU_FAST_NO_HZ)) pr_info("\tRCU dyntick-idle grace-period acceleration is enabled.\n"); |