diff options
author | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2014-06-04 13:46:03 -0700 |
---|---|---|
committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2014-07-09 09:15:02 -0700 |
commit | c0f489d2c6fec8994c642c2ec925eb858727dc7b (patch) | |
tree | e72f709231a498626a149ef676bd60ff0e1b26c3 /Documentation/DocBook/genericirq.tmpl | |
parent | abaa93d9e1de2c29297e69ddba8ddd38f15064cf (diff) |
rcu: Bind grace-period kthreads to non-NO_HZ_FULL CPUs
Binding the grace-period kthreads to the timekeeping CPU resulted in
significant performance decreases for some workloads. For more detail,
see:
https://lkml.org/lkml/2014/6/3/395 for benchmark numbers
https://lkml.org/lkml/2014/6/4/218 for CPU statistics
It turns out that it is necessary to bind the grace-period kthreads
to the timekeeping CPU only when all but CPU 0 is a nohz_full CPU
on the one hand or if CONFIG_NO_HZ_FULL_SYSIDLE=y on the other.
In other cases, it suffices to bind the grace-period kthreads to the
set of non-nohz_full CPUs.
This commit therefore creates a tick_nohz_not_full_mask that is the
complement of tick_nohz_full_mask, and then binds the grace-period
kthread to the set of CPUs indicated by this new mask, which covers
the CONFIG_NO_HZ_FULL_SYSIDLE=n case. The CONFIG_NO_HZ_FULL_SYSIDLE=y
case still binds the grace-period kthreads to the timekeeping CPU.
This commit also includes the tick_nohz_full_enabled() check suggested
by Frederic Weisbecker.
Reported-by: Jet Chen <jet.chen@intel.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
[ paulmck: Created housekeeping_affine() and housekeeping_mask per
fweisbec feedback. ]
Diffstat (limited to 'Documentation/DocBook/genericirq.tmpl')
0 files changed, 0 insertions, 0 deletions