kernel_optimize_test/arch
Benjamin Gaignard 022eb8ae8b ARM: 8938/1: kernel: initialize broadcast hrtimer based clock event device
On platforms implementing CPU power management, the CPUidle subsystem
can allow CPUs to enter idle states where local timers logic is lost on power
down. To keep the software timers functional the kernel relies on an
always-on broadcast timer to be present in the platform to relay the
interrupt signalling the timer expiries.

For platforms implementing CPU core gating that do not implement an always-on
HW timer or implement it in a broken way, this patch adds code to initialize
the kernel hrtimer based clock event device upon boot (which can be chosen as
tick broadcast device by the kernel).
It relies on a dynamically chosen CPU to be always powered-up. This CPU then
relays the timer interrupt to CPUs in deep-idle states through its HW local
timer device.

Having a CPU always-on has implications on power management platform
capabilities and makes CPUidle suboptimal, since at least a CPU is kept
always in a shallow idle state by the kernel to relay timer interrupts,
but at least leaves the kernel with a functional system with some working
power management capabilities.

The hrtimer based clock event device is unconditionally registered, but
has the lowest possible rating such that any broadcast-capable HW clock
event device present will be chosen in preference as the tick broadcast
device.

Signed-off-by: Benjamin Gaignard <benjamin.gaignard@st.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
2019-11-16 10:51:24 +00:00
..
alpha mm: introduce MADV_PAGEOUT 2019-09-25 17:51:41 -07:00
arc mm: treewide: clarify pgtable_page_{ctor,dtor}() naming 2019-09-26 10:10:44 -07:00
arm ARM: 8938/1: kernel: initialize broadcast hrtimer based clock event device 2019-11-16 10:51:24 +00:00
arm64 ARM: SoC fixes 2019-10-25 16:00:47 -04:00
c6x mm: consolidate pgtable_cache_init() and pgd_cache_init() 2019-09-24 15:54:09 -07:00
csky csky-for-linus-5.4-rc1: arch/csky patches for 5.4-rc1 2019-09-30 10:16:17 -07:00
h8300 mm: consolidate pgtable_cache_init() and pgd_cache_init() 2019-09-24 15:54:09 -07:00
hexagon mm: treewide: clarify pgtable_page_{ctor,dtor}() naming 2019-09-26 10:10:44 -07:00
ia64 Merge branch 'akpm' (patches from Andrew) 2019-09-24 16:10:23 -07:00
m68k mm: treewide: clarify pgtable_page_{ctor,dtor}() naming 2019-09-26 10:10:44 -07:00
microblaze Merge branch 'akpm' (patches from Andrew) 2019-09-24 16:10:23 -07:00
mips MIPS: tlbex: Fix build_restore_pagemask KScratch restore 2019-10-23 21:12:49 -07:00
nds32 mm: consolidate pgtable_cache_init() and pgd_cache_init() 2019-09-24 15:54:09 -07:00
nios2 nios2 update for v5.4-rc1 2019-09-27 13:02:19 -07:00
openrisc mm: treewide: clarify pgtable_page_{ctor,dtor}() naming 2019-09-26 10:10:44 -07:00
parisc parisc: Fix vmap memory leak in ioremap()/iounmap() 2019-10-14 21:44:17 +02:00
powerpc KVM: PPC: Book3S HV: XIVE: Ensure VP isn't already in use 2019-10-15 16:09:11 +11:00
riscv riscv: cleanup do_trap_break 2019-10-25 16:32:38 -07:00
s390 s390/kaslr: add support for R_390_GLOB_DAT relocation type 2019-10-22 17:55:51 +02:00
sh mm: treewide: clarify pgtable_page_{ctor,dtor}() naming 2019-09-26 10:10:44 -07:00
sparc sparc64: disable fast-GUP due to unexplained oopses 2019-10-15 09:56:36 -07:00
um mm: treewide: clarify pgtable_page_{ctor,dtor}() naming 2019-09-26 10:10:44 -07:00
unicore32 mm: treewide: clarify pgtable_page_{ctor,dtor}() naming 2019-09-26 10:10:44 -07:00
x86 Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-10-27 07:14:40 -04:00
xtensa xtensa: fix change_bit in exclusive access option 2019-10-16 00:14:33 -07:00
.gitignore
Kconfig arm64, mm: make randomization selected by generic topdown mmap layout 2019-09-24 15:54:11 -07:00