| Message ID | 20210719010845.31898-1-chanho.min@lge.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | mm: make falutaround selectable | expand |
On Mon, Jul 19, 2021 at 10:08:45AM +0900, Chanho Min wrote: > While faultaround can have performance gains, on certain platform it > increases pss and causes swap to occur more frequently. This patch allows > to unselect faultaround on platforms that do not want this behavior. It would be better if we could determine the circumstances under which faultaround is causing problems and automatically disable it without asking the sysadmin to determine that. Can you tell us more about the workload?
s/falutaround/faultaround/ On 19.07.21 03:08, Chanho Min wrote: > While faultaround can have performance gains, on certain platform it > increases pss and causes swap to occur more frequently. This patch allows > to unselect faultaround on platforms that do not want this behavior. > > Signed-off-by: Chanho Min <chanho.min@lge.com> > --- > mm/Kconfig | 6 ++++++ > mm/memory.c | 4 ++++ > 2 files changed, 10 insertions(+) > > diff --git a/mm/Kconfig b/mm/Kconfig > index 39a6a977537d..8f834386e7f3 100644 > --- a/mm/Kconfig > +++ b/mm/Kconfig > @@ -750,4 +750,10 @@ config ARCH_HAS_PTE_SPECIAL > config ARCH_HAS_HUGEPD > bool > > +config FAULT_AROUND > + bool "Enable fault around" > + default y > + help > + This option enables fault around. If say N, fault_around_bytes set to PAGE_SIZE > + and disables fault around. > endmenu > diff --git a/mm/memory.c b/mm/memory.c > index 10d2e4734e82..0bb037265dda 100644 > --- a/mm/memory.c > +++ b/mm/memory.c > @@ -3500,7 +3500,11 @@ vm_fault_t finish_fault(struct vm_fault *vmf) > } > > static unsigned long fault_around_bytes __read_mostly = > +#ifdef CONFIG_FAULT_AROUND > rounddown_pow_of_two(65536); > +#else > + PAGE_SIZE; > +#endif > > #ifdef CONFIG_DEBUG_FS > static int fault_around_bytes_get(void *data, u64 *val) >
diff --git a/mm/Kconfig b/mm/Kconfig index 39a6a977537d..8f834386e7f3 100644 --- a/mm/Kconfig +++ b/mm/Kconfig @@ -750,4 +750,10 @@ config ARCH_HAS_PTE_SPECIAL config ARCH_HAS_HUGEPD bool +config FAULT_AROUND + bool "Enable fault around" + default y + help + This option enables fault around. If say N, fault_around_bytes set to PAGE_SIZE + and disables fault around. endmenu diff --git a/mm/memory.c b/mm/memory.c index 10d2e4734e82..0bb037265dda 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -3500,7 +3500,11 @@ vm_fault_t finish_fault(struct vm_fault *vmf) } static unsigned long fault_around_bytes __read_mostly = +#ifdef CONFIG_FAULT_AROUND rounddown_pow_of_two(65536); +#else + PAGE_SIZE; +#endif #ifdef CONFIG_DEBUG_FS static int fault_around_bytes_get(void *data, u64 *val)
While faultaround can have performance gains, on certain platform it increases pss and causes swap to occur more frequently. This patch allows to unselect faultaround on platforms that do not want this behavior. Signed-off-by: Chanho Min <chanho.min@lge.com> --- mm/Kconfig | 6 ++++++ mm/memory.c | 4 ++++ 2 files changed, 10 insertions(+)