Re: [PATCH 01/10] x86: Change size of APICIDs from u8 to u16

From: Mel Gorman
Date: Mon Jan 14 2008 - 07:23:26 EST


On (13/01/08 10:34), travis@xxxxxxx didst pronounce:
> Change the size of APICIDs from u8 to u16. This partially
> supports the new x2apic mode that will be present on future
> processor chips. (Chips actually support 32-bit APICIDs, but that
> change is more intrusive. Supporting 16-bit is sufficient for now).
>
> Signed-off-by: Jack Steiner <steiner@xxxxxxx>
>
> I've included just the partial change from u8 to u16 apicids. The
> remaining x2apic changes will be in a separate patch.
>
> In addition, the fake_node_to_pxm_map[] and fake_apicid_to_node[]
> tables have been moved from local data to the __initdata section
> reducing stack pressure when MAX_NUMNODES and MAX_LOCAL_APIC are
> increased in size.
>

Does this make a different to inter-node effects?

> Signed-off-by: Mike Travis <travis@xxxxxxx>
> Reviewed-by: Christoph Lameter <clameter@xxxxxxx>
> ---
> arch/x86/kernel/genapic_64.c | 4 ++--
> arch/x86/kernel/mpparse_64.c | 4 ++--
> arch/x86/kernel/smpboot_64.c | 2 +-
> arch/x86/mm/numa_64.c | 2 +-
> arch/x86/mm/srat_64.c | 22 +++++++++++++---------
> include/asm-x86/processor.h | 14 +++++++-------
> include/asm-x86/smp_64.h | 8 ++++----
> 7 files changed, 30 insertions(+), 26 deletions(-)
>
> --- a/arch/x86/kernel/genapic_64.c
> +++ b/arch/x86/kernel/genapic_64.c
> @@ -32,10 +32,10 @@
> * array during this time. Is it zeroed when the per_cpu
> * data area is removed.
> */
> -u8 x86_cpu_to_apicid_init[NR_CPUS] __initdata
> +u16 x86_cpu_to_apicid_init[NR_CPUS] __initdata
> = { [0 ... NR_CPUS-1] = BAD_APICID };
> void *x86_cpu_to_apicid_ptr;
> -DEFINE_PER_CPU(u8, x86_cpu_to_apicid) = BAD_APICID;
> +DEFINE_PER_CPU(u16, x86_cpu_to_apicid) = BAD_APICID;
> EXPORT_PER_CPU_SYMBOL(x86_cpu_to_apicid);
>
> struct genapic __read_mostly *genapic = &apic_flat;
> --- a/arch/x86/kernel/mpparse_64.c
> +++ b/arch/x86/kernel/mpparse_64.c
> @@ -67,7 +67,7 @@ unsigned disabled_cpus __cpuinitdata;
> /* Bitmask of physically existing CPUs */
> physid_mask_t phys_cpu_present_map = PHYSID_MASK_NONE;
>
> -u8 bios_cpu_apicid[NR_CPUS] = { [0 ... NR_CPUS-1] = BAD_APICID };
> +u16 bios_cpu_apicid[NR_CPUS] = { [0 ... NR_CPUS-1] = BAD_APICID };
>
>
> /*
> @@ -132,7 +132,7 @@ static void __cpuinit MP_processor_info(
> * area is created.
> */
> if (x86_cpu_to_apicid_ptr) {
> - u8 *x86_cpu_to_apicid = (u8 *)x86_cpu_to_apicid_ptr;
> + u16 *x86_cpu_to_apicid = (u16 *)x86_cpu_to_apicid_ptr;
> x86_cpu_to_apicid[cpu] = m->mpc_apicid;
> } else {
> per_cpu(x86_cpu_to_apicid, cpu) = m->mpc_apicid;
> --- a/arch/x86/kernel/smpboot_64.c
> +++ b/arch/x86/kernel/smpboot_64.c
> @@ -65,7 +65,7 @@ int smp_num_siblings = 1;
> EXPORT_SYMBOL(smp_num_siblings);
>
> /* Last level cache ID of each logical CPU */
> -DEFINE_PER_CPU(u8, cpu_llc_id) = BAD_APICID;
> +DEFINE_PER_CPU(u16, cpu_llc_id) = BAD_APICID;
>
> /* Bitmask of currently online CPUs */
> cpumask_t cpu_online_map __read_mostly;
> --- a/arch/x86/mm/numa_64.c
> +++ b/arch/x86/mm/numa_64.c
> @@ -627,7 +627,7 @@ void __init init_cpu_to_node(void)
> int i;
>
> for (i = 0; i < NR_CPUS; i++) {
> - u8 apicid = x86_cpu_to_apicid_init[i];
> + u16 apicid = x86_cpu_to_apicid_init[i];
>
> if (apicid == BAD_APICID)
> continue;
> --- a/arch/x86/mm/srat_64.c
> +++ b/arch/x86/mm/srat_64.c
> @@ -130,6 +130,9 @@ void __init
> acpi_numa_processor_affinity_init(struct acpi_srat_cpu_affinity *pa)
> {
> int pxm, node;
> + int apic_id;
> +
> + apic_id = pa->apic_id;
> if (srat_disabled())
> return;
> if (pa->header.length != sizeof(struct acpi_srat_cpu_affinity)) {
> @@ -145,10 +148,10 @@ acpi_numa_processor_affinity_init(struct
> bad_srat();
> return;
> }
> - apicid_to_node[pa->apic_id] = node;
> + apicid_to_node[apic_id] = node;
> acpi_numa = 1;
> printk(KERN_INFO "SRAT: PXM %u -> APIC %u -> Node %u\n",
> - pxm, pa->apic_id, node);
> + pxm, apic_id, node);
> }
>
> int update_end_of_memory(unsigned long end) {return -1;}
> @@ -343,7 +346,8 @@ int __init acpi_scan_nodes(unsigned long
> /* First clean up the node list */
> for (i = 0; i < MAX_NUMNODES; i++) {
> cutoff_node(i, start, end);
> - if ((nodes[i].end - nodes[i].start) < NODE_MIN_SIZE) {
> + /* ZZZ why was this needed. At least add a comment */
> + if (nodes[i].end && (nodes[i].end - nodes[i].start) < NODE_MIN_SIZE) {

Care to actually add a comment? This looks like a note to yourself that
got missed.

> unparse_node(i);
> node_set_offline(i);
> }
> @@ -384,6 +388,12 @@ int __init acpi_scan_nodes(unsigned long
> }
>
> #ifdef CONFIG_NUMA_EMU
> +static int fake_node_to_pxm_map[MAX_NUMNODES] __initdata = {
> + [0 ... MAX_NUMNODES-1] = PXM_INVAL
> +};
> +static unsigned char fake_apicid_to_node[MAX_LOCAL_APIC] __initdata = {
> + [0 ... MAX_LOCAL_APIC-1] = NUMA_NO_NODE
> +};
> static int __init find_node_by_addr(unsigned long addr)
> {
> int ret = NUMA_NO_NODE;
> @@ -414,12 +424,6 @@ static int __init find_node_by_addr(unsi
> void __init acpi_fake_nodes(const struct bootnode *fake_nodes, int num_nodes)
> {
> int i, j;
> - int fake_node_to_pxm_map[MAX_NUMNODES] = {
> - [0 ... MAX_NUMNODES-1] = PXM_INVAL
> - };
> - unsigned char fake_apicid_to_node[MAX_LOCAL_APIC] = {
> - [0 ... MAX_LOCAL_APIC-1] = NUMA_NO_NODE
> - };
>
> printk(KERN_INFO "Faking PXM affinity for fake nodes on real "
> "topology.\n");
> --- a/include/asm-x86/processor.h
> +++ b/include/asm-x86/processor.h
> @@ -86,14 +86,14 @@ struct cpuinfo_x86 {
> #ifdef CONFIG_SMP
> cpumask_t llc_shared_map; /* cpus sharing the last level cache */
> #endif
> - unsigned char x86_max_cores; /* cpuid returned max cores value */
> - unsigned char apicid;
> - unsigned short x86_clflush_size;
> + u16 x86_max_cores; /* cpuid returned max cores value */
> + u16 apicid;
> + u16 x86_clflush_size;
> #ifdef CONFIG_SMP
> - unsigned char booted_cores; /* number of cores as seen by OS */
> - __u8 phys_proc_id; /* Physical processor id. */
> - __u8 cpu_core_id; /* Core id */
> - __u8 cpu_index; /* index into per_cpu list */
> + u16 booted_cores; /* number of cores as seen by OS */
> + u16 phys_proc_id; /* Physical processor id. */
> + u16 cpu_core_id; /* Core id */
> + u16 cpu_index; /* index into per_cpu list */
> #endif
> } __attribute__((__aligned__(SMP_CACHE_BYTES)));
>
> --- a/include/asm-x86/smp_64.h
> +++ b/include/asm-x86/smp_64.h
> @@ -26,14 +26,14 @@ extern void unlock_ipi_call_lock(void);
> extern int smp_call_function_mask(cpumask_t mask, void (*func)(void *),
> void *info, int wait);
>
> -extern u8 __initdata x86_cpu_to_apicid_init[];
> +extern u16 __initdata x86_cpu_to_apicid_init[];
> extern void *x86_cpu_to_apicid_ptr;
> -extern u8 bios_cpu_apicid[];
> +extern u16 bios_cpu_apicid[];
>
> DECLARE_PER_CPU(cpumask_t, cpu_sibling_map);
> DECLARE_PER_CPU(cpumask_t, cpu_core_map);
> -DECLARE_PER_CPU(u8, cpu_llc_id);
> -DECLARE_PER_CPU(u8, x86_cpu_to_apicid);
> +DECLARE_PER_CPU(u16, cpu_llc_id);
> +DECLARE_PER_CPU(u16, x86_cpu_to_apicid);
>
> static inline int cpu_present_to_apicid(int mps_cpu)
> {
>
> --
>
> --
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>

--
Mel Gorman
Part-time Phd Student Linux Technology Center
University of Limerick IBM Dublin Software Lab
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