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author | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2015-02-19 10:51:32 -0800 |
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committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2015-02-26 12:03:03 -0800 |
commit | ee42571f4381f184e2672dd34ab411e5bf5bd5e0 (patch) | |
tree | 6dc7829e3529fae2f519ab8dc1a665f8109cc311 /tools | |
parent | 5afff48bdf7481570c9385a8a674a81ffb8f09ee (diff) | |
download | op-kernel-dev-ee42571f4381f184e2672dd34ab411e5bf5bd5e0.zip op-kernel-dev-ee42571f4381f184e2672dd34ab411e5bf5bd5e0.tar.gz |
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 'tools')
0 files changed, 0 insertions, 0 deletions