Messages in this thread | | | From | Chen Yu <> | Subject | [PATCH 0/2][RFC] Makes sd->flags sysctl writable | Date | Tue, 7 Jul 2020 03:36:13 +0800 |
| |
It was found that recently the flags of sched domain could not be customized via sysctl, which might make it a little inconenient for performance tuning/debugging.
echo 343 > /proc/sys/kernel/sched_domain/cpu0/domain0/flags bash: flags: Permission denied
343 stands for: (SD_BALANCE_NEWIDLE SD_BALANCE_EXEC SD_BALANCE_FORK SD_WAKE_AFFINE)
As mentioned in Commit 9818427c6270 ("sched/debug: Make sd->flags sysctl read-only"), the flags field is made read-only, due to the concerns that the sd flags and the per cpu cache domain pointer are not coherent.
This trial patch tries to address the issue by updating the cache domain pointer once the flag has been modified. So that the sd->flags could be changed via sysctl.
I'm not sure if there is other purpose that we've set the flags to read-only, but it seems that keeping the sd->flags writable could help diagnose the system easier. Any comment would be appreciated.
Chen Yu (2): sched/topology: Add update_domain_cpu() sched/debug: Make sd->flags sysctl writable again
include/linux/sched/topology.h | 5 +++++ kernel/sched/debug.c | 30 +++++++++++++++++++++++++++--- kernel/sched/topology.c | 11 +++++++++++ 3 files changed, 43 insertions(+), 3 deletions(-)
-- 2.17.1
| |