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authorPaul E. McKenney <paulmck@linux.vnet.ibm.com>2015-02-19 21:51:32 +0300
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2015-02-26 23:03:03 +0300
commitee42571f4381f184e2672dd34ab411e5bf5bd5e0 (patch)
tree6dc7829e3529fae2f519ab8dc1a665f8109cc311 /include/linux/rcupdate.h
parent5afff48bdf7481570c9385a8a674a81ffb8f09ee (diff)
downloadlinux-ee42571f4381f184e2672dd34ab411e5bf5bd5e0.tar.xz
rcu: Add Kconfig option to expedite grace periods during boot
This commit adds a CONFIG_RCU_EXPEDITE_BOOT Kconfig parameter that emulates a very early boot rcu_expedite_gp(). A late-boot call to rcu_end_inkernel_boot() will provide the corresponding rcu_unexpedite_gp(). The late-boot call to rcu_end_inkernel_boot() should be made just before init is spawned. According to Arjan: > To show the boot time, I'm using the timestamp of the "Write protecting" > line, that's pretty much the last thing we print prior to ring 3 execution. > > A kernel with default RCU behavior (inside KVM, only virtual devices) > looks like this: > > [ 0.038724] Write protecting the kernel read-only data: 10240k > > a kernel with expedited RCU (using the command line option, so that I > don't have to recompile between measurements and thus am completely > oranges-to-oranges) > > [ 0.031768] Write protecting the kernel read-only data: 10240k > > which, in percentage, is an 18% improvement. Reported-by: Arjan van de Ven <arjan@linux.intel.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Tested-by: Arjan van de Ven <arjan@linux.intel.com>
Diffstat (limited to 'include/linux/rcupdate.h')
-rw-r--r--include/linux/rcupdate.h1
1 files changed, 1 insertions, 0 deletions
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index 57a4d1f73a00..b9f039b11d31 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -278,6 +278,7 @@ static inline int rcu_preempt_depth(void)
/* Internal to kernel */
void rcu_init(void);
+void rcu_end_inkernel_boot(void);
void rcu_sched_qs(void);
void rcu_bh_qs(void);
void rcu_check_callbacks(int user);