Messages in this thread | | | Subject | Re: [PATCH v2 3/9] sched: Remove checks against SD_LOAD_BALANCE | From | Dietmar Eggemann <> | Date | Mon, 23 Mar 2020 15:26:35 +0100 |
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On 19.03.20 13:05, Valentin Schneider wrote: > > On Thu, Mar 19 2020, Dietmar Eggemann wrote: >> On 11.03.20 19:15, Valentin Schneider wrote:
[...]
> Your comments make me realize that changelog isn't great, what about the > following? > > --- > > The SD_LOAD_BALANCE flag is set unconditionally for all domains in > sd_init(). By making the sched_domain->flags syctl interface read-only, we > have removed the last piece of code that could clear that flag - as such, > it will now be always present. Rather than to keep carrying it along, we > can work towards getting rid of it entirely. > > cpusets don't need it because they can make CPUs be attached to the NULL > domain (e.g. cpuset with sched_load_balance=0), or to a partitionned
s/partitionned/partitioned
> root_domain, i.e. a sched_domain hierarchy that doesn't span the entire > system (e.g. root cpuset with sched_load_balance=0 and sibling cpusets with > sched_load_balance=1). > > isolcpus apply the same "trick": isolated CPUs are explicitly taken out of > the sched_domain rebuild (using housekeeping_cpumask()), so they get the > NULL domain treatment as well. > > Remove the checks against SD_LOAD_BALANCE.
Sounds better to me:
Essentially, I was referring to examples like:
Hikey960 - 2x4
(A) exclusive cpusets:
root@h960:/sys/fs/cgroup/cpuset# mkdir cs1 root@h960:/sys/fs/cgroup/cpuset# echo 1 > cs1/cpuset.cpu_exclusive root@h960:/sys/fs/cgroup/cpuset# echo 0 > cs1/cpuset.mems root@h960:/sys/fs/cgroup/cpuset# echo 0-2 > cs1/cpuset.cpus root@h960:/sys/fs/cgroup/cpuset# mkdir cs2 root@h960:/sys/fs/cgroup/cpuset# echo 1 > cs2/cpuset.cpu_exclusive root@h960:/sys/fs/cgroup/cpuset# echo 0 > cs2/cpuset.mems root@h960:/sys/fs/cgroup/cpuset# echo 3-5 > cs2/cpuset.cpus root@h960:/sys/fs/cgroup/cpuset# echo 0 > cpuset.sched_load_balance
root@h960:/proc/sys/kernel# tree -d sched_domain
├── cpu0 │ └── domain0 ├── cpu1 │ └── domain0 ├── cpu2 │ └── domain0 ├── cpu3 │ └── domain0 ├── cpu4 │ ├── domain0 │ └── domain1 ├── cpu5 │ ├── domain0 │ └── domain1 ├── cpu6 └── cpu7
(B) non-exclusive cpuset:
root@h960:/sys/fs/cgroup/cpuset# echo 0 > cpuset.sched_load_balance
[ 8661.240385] CPU1 attaching NULL sched-domain. [ 8661.244802] CPU2 attaching NULL sched-domain. [ 8661.249255] CPU3 attaching NULL sched-domain. [ 8661.253623] CPU4 attaching NULL sched-domain. [ 8661.257989] CPU5 attaching NULL sched-domain. [ 8661.262363] CPU6 attaching NULL sched-domain. [ 8661.266730] CPU7 attaching NULL sched-domain.
root@h960:/sys/fs/cgroup/cpuset# mkdir cs1 root@h960:/sys/fs/cgroup/cpuset# echo 0-5 > cs1/cpuset.cpus
root@h960:/proc/sys/kernel# tree -d sched_domain
├── cpu0 │ ├── domain0 │ └── domain1 ├── cpu1 │ ├── domain0 │ └── domain1 ├── cpu2 │ ├── domain0 │ └── domain1 ├── cpu3 │ ├── domain0 │ └── domain1 ├── cpu4 │ ├── domain0 │ └── domain1 ├── cpu5 │ ├── domain0 │ └── domain1 ├── cpu6 └── cpu7
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