Tejun Heo 6a010a49b6 cgroup: Make !percpu threadgroup_rwsem operations optional ... 3942a9bd7b ("locking, rcu, cgroup: Avoid synchronize_sched() in __cgroup_procs_write()") disabled percpu operations on threadgroup_rwsem because the impiled synchronize_rcu() on write locking was pushing up the latencies too much for android which constantly moves processes between cgroups. This makes the hotter paths - fork and exit - slower as they're always forced into the slow path. There is no reason to force this on everyone especially given that more common static usage pattern can now completely avoid write-locking the rwsem. Write-locking is elided when turning on and off controllers on empty sub-trees and CLONE_INTO_CGROUP enables seeding a cgroup without grabbing the rwsem. Restore the default percpu operations and introduce the mount option "favordynmods" and config option CGROUP_FAVOR_DYNMODS for users who need lower latencies for the dynamic operations. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Christian Brauner <brauner@kernel.org> Cc: Michal Koutn� <mkoutny@suse.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: John Stultz <john.stultz@linaro.org> Cc: Dmitry Shmidt <dimitrysh@google.com> Cc: Oleg Nesterov <oleg@redhat.com>		2022-07-23 04:29:02 -10:00
..
calibrate.c	License cleanup: add SPDX GPL-2.0 license identifier to files with no license	2017-11-02 11:10:55 +01:00
do_mounts.c	block: remove genhd.h	2022-02-02 07:49:59 -07:00
do_mounts.h	init: add an init_mknod helper	2020-07-31 08:17:54 +02:00
do_mounts_initrd.c	kernel/do_mount_initrd: move real_root_dev sysctls to its own file	2022-04-06 13:43:44 -07:00
do_mounts_rd.c	init: add an init_unlink helper	2020-07-31 08:17:52 +02:00
init_task.c	kcsan: Remove redundant zero-initialization of globals	2021-12-09 16:42:26 -08:00
initramfs.c	This set of changes updates init and user mode helper tasks to be	2022-06-03 16:03:05 -07:00
Kconfig	cgroup: Make !percpu threadgroup_rwsem operations optional	2022-07-23 04:29:02 -10:00
main.c	This set of changes updates init and user mode helper tasks to be	2022-06-03 16:03:05 -07:00
Makefile	sched/preempt: Tell about PREEMPT_DYNAMIC on kernel headers	2022-03-11 15:36:35 +01:00
noinitramfs.c	init: move usermodehelper_enable() to populate_rootfs()	2021-09-08 11:50:27 -07:00
version.c	kbuild: add an elfnote for whether vmlinux is built with lto	2021-04-25 05:25:42 +09:00