Messages in this thread | | | Date | Mon, 29 Mar 2021 11:07:35 +0100 | From | Marc Zyngier <> | Subject | Re: [RFC PATCH 3/3] arm/arm64: Use gic_ipi_send_single() to inject single IPI |
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On Mon, 29 Mar 2021 09:52:10 +0100, Jingyi Wang <wangjingyi11@huawei.com> wrote: > > Currently, arm use gic_ipi_send_mask() to inject single IPI, which > make the procedure a little complex. We use gic_ipi_send_single() > instead as some other archs. > > Signed-off-by: Jingyi Wang <wangjingyi11@huawei.com> > --- > arch/arm/kernel/smp.c | 16 +++++++++++++--- > arch/arm64/kernel/smp.c | 16 +++++++++++++--- > 2 files changed, 26 insertions(+), 6 deletions(-) > > diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c > index 74679240a9d8..369ce529cdd8 100644 > --- a/arch/arm/kernel/smp.c > +++ b/arch/arm/kernel/smp.c > @@ -534,6 +534,8 @@ static const char *ipi_types[NR_IPI] __tracepoint_string = { > }; > > static void smp_cross_call(const struct cpumask *target, unsigned int ipinr); > +static void smp_cross_call_single(const struct cpumask *target, int cpu, > + unsigned int ipinr);
Why does this function need to take both a cpumask *and* a cpu, given that they represent the same thing?
> > void show_ipi_list(struct seq_file *p, int prec) > { > @@ -564,14 +566,15 @@ void arch_send_wakeup_ipi_mask(const struct cpumask *mask) > > void arch_send_call_function_single_ipi(int cpu) > { > - smp_cross_call(cpumask_of(cpu), IPI_CALL_FUNC); > + smp_cross_call_single(cpumask_of(cpu), cpu, IPI_CALL_FUNC); > } > > #ifdef CONFIG_IRQ_WORK > void arch_irq_work_raise(void) > { > + int cpu = smp_processor_id(); > if (arch_irq_work_has_interrupt()) > - smp_cross_call(cpumask_of(smp_processor_id()), IPI_IRQ_WORK); > + smp_cross_call(cpumask_of(cpu), cpu, IPI_IRQ_WORK);
Why isn't that a call to smp_cross_call_single()?
> } > #endif > > @@ -707,6 +710,13 @@ static void smp_cross_call(const struct cpumask *target, unsigned int ipinr) > __ipi_send_mask(ipi_desc[ipinr], target); > } > > +static void smp_cross_call_single(const struct cpumask *target, int cpu, > + unsigned int ipinr) > +{ > + trace_ipi_raise_rcuidle(target, ipi_types[ipinr]);
Why don't you compute the cpumask here^^?
> + __ipi_send_single(ipi_desc[ipinr], cpu); > +} > + > static void ipi_setup(int cpu) > { > int i; > @@ -744,7 +754,7 @@ void __init set_smp_ipi_range(int ipi_base, int n) > > void smp_send_reschedule(int cpu) > { > - smp_cross_call(cpumask_of(cpu), IPI_RESCHEDULE); > + smp_cross_call_single(cpumask_of(cpu), cpu, IPI_RESCHEDULE); > } > > void smp_send_stop(void) > diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c > index 357590beaabb..d290b6dc5a6e 100644 > --- a/arch/arm64/kernel/smp.c > +++ b/arch/arm64/kernel/smp.c
Similar comments for the arm64 side.
Overall, this needs to be backed by data that indicates that there is an actual benefit for this extra complexity.
Thanks,
M.
-- Without deviation from the norm, progress is not possible.
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