Applied, thanks!
Damien Zammit, le sam. 05 août 2023 07:49:54 +0000, a ecrit:
> This speeds up smp slightly by reducing the cpu_number()
> complexity to have no branching, just a look up table.
> It also addresses the problem that CPU_NUMBER was only using
> raw apic_id as an approximation of the kernel_id.
> Other improvements were to remove unnecessary checks now that
> the lookup table always resolves to a valid value.
> ---
> i386/i386/apic.c | 33 ++++++++++++++++++++++-----------
> i386/i386/apic.h | 2 ++
> i386/i386/cpu_number.c | 19 +------------------
> i386/i386/cpu_number.h | 1 +
> i386/i386at/acpi_parse_apic.c | 2 ++
> 5 files changed, 28 insertions(+), 29 deletions(-)
>
> diff --git a/i386/i386/apic.c b/i386/i386/apic.c
> index c399074d..2bb8e3f1 100644
> --- a/i386/i386/apic.c
> +++ b/i386/i386/apic.c
> @@ -35,6 +35,11 @@
> static ApicLocalUnit dummy_lapic = {0};
> volatile ApicLocalUnit* lapic = &dummy_lapic;
>
> +/* This lookup table of [apic_id] -> kernel_id is initially populated with
> zeroes
> + * so every lookup results in master processor until real kernel ids are
> populated.
> + */
> +int cpu_id_lut[UINT8_MAX + 1] = {0};
> +
> ApicInfo apic_data;
>
> /*
> @@ -137,14 +142,7 @@ apic_get_cpu_apic_id(int kernel_id)
> int
> apic_get_cpu_kernel_id(uint16_t apic_id)
> {
> - int i;
> -
> - for (i = 0; i < apic_data.ncpus; i++) {
> - if (apic_data.cpu_lapic_list[i] == apic_id)
> - return i;
> - }
> -
> - return -1;
> + return cpu_id_lut[apic_id];
> }
>
> /* apic_get_lapic: returns a reference to the common memory address for
> Local APIC. */
> @@ -187,9 +185,6 @@ apic_get_num_ioapics(void)
> int
> apic_get_current_cpu(void)
> {
> - if(lapic == NULL)
> - return -1;
> -
> return (lapic->apic_id.r >> 24) & 0xff;
> }
>
> @@ -222,6 +217,22 @@ int apic_refit_cpulist(void)
> return 0;
> }
>
> +/*
> + * apic_generate_cpu_id_lut: Generate lookup table of cpu kernel ids from
> apic ids
> + */
> +void apic_generate_cpu_id_lut(void)
> +{
> + int i, apic_id;
> +
> + for (i = 0; i < apic_data.ncpus; i++) {
> + apic_id = apic_get_cpu_apic_id(i);
> + if (apic_id >= 0)
> + cpu_id_lut[apic_id] = i;
> + else
> + printf("apic_get_cpu_apic_id(%d) failed...\n", i);
> + }
> +}
> +
> /*
> * apic_print_info: shows the list of Local APIC and IOAPIC.
> * Shows each CPU and IOAPIC, with Its Kernel ID and APIC ID.
> diff --git a/i386/i386/apic.h b/i386/i386/apic.h
> index 73e32dfe..e870dcf8 100644
> --- a/i386/i386/apic.h
> +++ b/i386/i386/apic.h
> @@ -238,6 +238,7 @@ uint8_t apic_get_num_ioapics(void);
> int apic_get_current_cpu(void);
> void apic_print_info(void);
> int apic_refit_cpulist(void);
> +void apic_generate_cpu_id_lut(void);
> void picdisable(void);
> void lapic_eoi(void);
> void ioapic_irq_eoi(int pin);
> @@ -250,6 +251,7 @@ void ioapic_configure(void);
> extern int timer_pin;
> extern void intnull(int unit);
> extern volatile ApicLocalUnit* lapic;
> +extern int cpu_id_lut[];
>
> #endif
>
> diff --git a/i386/i386/cpu_number.c b/i386/i386/cpu_number.c
> index 1d2fab3a..ef19e11f 100644
> --- a/i386/i386/cpu_number.c
> +++ b/i386/i386/cpu_number.c
> @@ -25,23 +25,6 @@
> #if NCPUS > 1
> int cpu_number(void)
> {
> - int kernel_id, apic_id;
> -
> - if (bspdone == 0)
> - return 0;
> -
> - apic_id = apic_get_current_cpu();
> - if (apic_id < 0) {
> - printf("apic_get_current_cpu() failed, assuming BSP\n");
> - apic_id = 0;
> - }
> -
> - kernel_id = apic_get_cpu_kernel_id(apic_id);
> - if (kernel_id < 0) {
> - printf("apic_get_cpu_kernel_id() failed, assuming BSP\n");
> - kernel_id = 0;
> - }
> -
> - return kernel_id;
> + return cpu_id_lut[apic_get_current_cpu()];
> }
> #endif
> diff --git a/i386/i386/cpu_number.h b/i386/i386/cpu_number.h
> index a5658471..c00896e8 100644
> --- a/i386/i386/cpu_number.h
> +++ b/i386/i386/cpu_number.h
> @@ -43,6 +43,7 @@
> movl %cs:lapic, reg ;\
> movl %cs:APIC_ID(reg), reg ;\
> shrl $24, reg ;\
> + movl %cs:CX(cpu_id_lut, reg), reg ;\
>
> #ifndef __ASSEMBLER__
> #include "kern/cpu_number.h"
> diff --git a/i386/i386at/acpi_parse_apic.c b/i386/i386at/acpi_parse_apic.c
> index 27e3410d..9cd861ed 100644
> --- a/i386/i386at/acpi_parse_apic.c
> +++ b/i386/i386at/acpi_parse_apic.c
> @@ -483,6 +483,8 @@ acpi_apic_setup(struct acpi_apic *apic)
> return ACPI_FIT_FAILURE;
> }
>
> + apic_generate_cpu_id_lut();
> +
> return ACPI_SUCCESS;
> }
>
> --
> 2.40.1
>
>
>
--
Samuel
---
Pour une évaluation indépendante, transparente et rigoureuse !
Je soutiens la Commission d'Évaluation de l'Inria.
