Messages in this thread | | | Date | Mon, 11 Jul 2022 21:35:04 +0800 | Subject | Re: [PATCH v2 2/4] mm: rmap: Allow platforms without mm_cpumask to defer TLB flush | From | Kefeng Wang <> |
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Hi Barry,
On 2022/7/11 11:46, Barry Song wrote: > From: Barry Song <v-songbaohua@oppo.com> > > Platforms like ARM64 have hareware TLB shootdown broadcast. They > don't maintain mm_cpumask but just send tlbi and related sync > instructions for TLB flush. task's mm_cpumask is normally empty > in this case. We also allow deferred TLB flush on this kind of > platforms. > > Signed-off-by: Barry Song <v-songbaohua@oppo.com>> > --- ... > diff --git a/mm/Kconfig b/mm/Kconfig > index 169e64192e48..7bf54f57ca01 100644 > --- a/mm/Kconfig > +++ b/mm/Kconfig > @@ -951,6 +951,9 @@ config ARCH_HAS_CURRENT_STACK_POINTER > register alias named "current_stack_pointer", this config can be > selected. > > +config ARCH_HAS_MM_CPUMASK > + bool > + > config ARCH_HAS_VM_GET_PAGE_PROT > bool > > diff --git a/mm/rmap.c b/mm/rmap.c > index 5bcb334cd6f2..13d4f9a1d4f1 100644 > --- a/mm/rmap.c > +++ b/mm/rmap.c > @@ -692,6 +692,10 @@ static bool should_defer_flush(struct mm_struct *mm, enum ttu_flags flags) > if (!(flags & TTU_BATCH_FLUSH)) > return false; > > +#ifndef CONFIG_ARCH_HAS_MM_CPUMASK > + return true; > +#endif > +
Here is another option to enable arch's tlbbatch defer
[1] https://patchwork.ozlabs.org/project/linuxppc-dev/patch/20171101101735.2318-2-khandual@linux.vnet.ibm.com/
> /* If remote CPUs need to be flushed then defer batch the flush */ > if (cpumask_any_but(mm_cpumask(mm), get_cpu()) < nr_cpu_ids) > should_defer = true;
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