On 05/24/2018 11:43 AM, Peter Zijlstra wrote: > On Thu, May 17, 2018 at 04:55:42PM -0400, Waiman Long wrote: >> The sched.load_balance flag is needed to enable CPU isolation similar to >> what can be done with the "isolcpus" kernel boot parameter. Its value >> can only be changed in a scheduling domain with no child cpusets. On >> a non-scheduling domain cpuset, the value of sched.load_balance is >> inherited from its parent. >> >> This flag is set by the parent and is not delegatable. >> >> Signed-off-by: Waiman Long <longman@xxxxxxxxxx> >> --- >> Documentation/cgroup-v2.txt | 24 ++++++++++++++++++++ >> kernel/cgroup/cpuset.c | 53 +++++++++++++++++++++++++++++++++++++++++---- >> 2 files changed, 73 insertions(+), 4 deletions(-) >> >> diff --git a/Documentation/cgroup-v2.txt b/Documentation/cgroup-v2.txt >> index 54d9e22..071b634d 100644 >> --- a/Documentation/cgroup-v2.txt >> +++ b/Documentation/cgroup-v2.txt >> @@ -1536,6 +1536,30 @@ Cpuset Interface Files >> CPUs of the parent cgroup. Once it is set, this flag cannot be >> cleared if there are any child cgroups with cpuset enabled. >> >> + A parent cgroup cannot distribute all its CPUs to child >> + scheduling domain cgroups unless its load balancing flag is >> + turned off. >> + >> + cpuset.sched.load_balance >> + A read-write single value file which exists on non-root >> + cpuset-enabled cgroups. It is a binary value flag that accepts >> + either "0" (off) or a non-zero value (on). This flag is set >> + by the parent and is not delegatable. >> + >> + When it is on, tasks within this cpuset will be load-balanced >> + by the kernel scheduler. Tasks will be moved from CPUs with >> + high load to other CPUs within the same cpuset with less load >> + periodically. >> + >> + When it is off, there will be no load balancing among CPUs on >> + this cgroup. Tasks will stay in the CPUs they are running on >> + and will not be moved to other CPUs. >> + >> + The initial value of this flag is "1". This flag is then >> + inherited by child cgroups with cpuset enabled. Its state >> + can only be changed on a scheduling domain cgroup with no >> + cpuset-enabled children. > I'm confused... why exactly do we have both domain and load_balance ? The domain is for partitioning the CPUs only. It doesn't change the load balancing state. So the load_balance flag is still need to turn on and off load balancing. Cheers, Longman -- To unsubscribe from this list: send the line "unsubscribe cgroups" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
