diff options
| author | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2015-04-14 19:33:59 -0700 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2015-04-14 19:33:59 -0700 |
| commit | 8d7dc9283f399e1fda4e48a1c453f689326d9396 (patch) | |
| tree | c63e3a78f675521d36c032319c26e9f85f942f20 /lib | |
| parent | 590ee7dbd569a012df705a5204fc5f1066f52b8c (diff) | |
| download | linux-8d7dc9283f399e1fda4e48a1c453f689326d9396.tar.bz2 | |
rcu: Control grace-period delays directly from value
In a misguided attempt to avoid an #ifdef, the use of the
gp_init_delay module parameter was conditioned on the corresponding
RCU_TORTURE_TEST_SLOW_INIT Kconfig variable, using IS_ENABLED() at
the point of use in the code. This meant that the compiler always saw
the delay, which meant that RCU_TORTURE_TEST_SLOW_INIT_DELAY had to be
unconditionally defined. This in turn caused "make oldconfig" to ask
pointless questions about the value of RCU_TORTURE_TEST_SLOW_INIT_DELAY
in cases where it was not even used.
This commit avoids these pointless questions by defining gp_init_delay
under #ifdef. In one branch, gp_init_delay is initialized to
RCU_TORTURE_TEST_SLOW_INIT_DELAY and is also a module parameter (thus
allowing boot-time modification), and in the other branch gp_init_delay
is a const variable initialized by default to zero.
This approach also simplifies the code at the delay point by eliminating
the IS_DEFINED(). Because gp_init_delay is constant zero in the no-delay
case intended for production use, the "gp_init_delay > 0" check causes
the delay to become dead code, as desired in this case. In addition,
this commit replaces magic constant "10" with the preprocessor variable
PER_RCU_NODE_PERIOD, which controls the number of grace periods that
are allowed to elapse at full speed before a delay is inserted.
Reported-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by:
Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/Kconfig.debug | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index 1ad74c0df01f..5f5ff7d7e5eb 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -1268,6 +1268,7 @@ config RCU_TORTURE_TEST_SLOW_INIT_DELAY int "How much to slow down RCU grace-period initialization" range 0 5 default 3 + depends on RCU_TORTURE_TEST_SLOW_INIT help This option specifies the number of jiffies to wait between each rcu_node structure initialization. |