on x86, before prefill_possible_map(), nr_cpu_ids will be NR_CPUS aka CONFIG_NR_CPUS
add nr_cpus= to set nr_cpu_ids. so we can simulate cpus <=8 on normal config.
instead of change NR_CPUS directly.
Signed-off-by: Yinghai Lu <[email protected]>
---
arch/ia64/kernel/acpi.c | 4 ++--
arch/x86/kernel/smpboot.c | 7 ++++---
init/main.c | 14 ++++++++++++++
3 files changed, 20 insertions(+), 5 deletions(-)
Index: linux-2.6/init/main.c
===================================================================
--- linux-2.6.orig/init/main.c
+++ linux-2.6/init/main.c
@@ -149,6 +149,20 @@ static int __init nosmp(char *str)
early_param("nosmp", nosmp);
+/* this is hard limit */
+static int __init nrcpus(char *str)
+{
+ int nr_cpus;
+
+ get_option(&str, &nr_cpus);
+ if (nr_cpus > 0 && nr_cpus < nr_cpu_ids)
+ nr_cpu_ids = nr_cpus;
+
+ return 0;
+}
+
+early_param("nr_cpus", nrcpus);
+
static int __init maxcpus(char *str)
{
get_option(&str, &setup_max_cpus);
Index: linux-2.6/arch/ia64/kernel/acpi.c
===================================================================
--- linux-2.6.orig/arch/ia64/kernel/acpi.c
+++ linux-2.6/arch/ia64/kernel/acpi.c
@@ -883,8 +883,8 @@ __init void prefill_possible_map(void)
possible = available_cpus + additional_cpus;
- if (possible > NR_CPUS)
- possible = NR_CPUS;
+ if (possible > nr_cpu_ids)
+ possible = nr_cpu_ids;
printk(KERN_INFO "SMP: Allowing %d CPUs, %d hotplug CPUs\n",
possible, max((possible - available_cpus), 0));
Index: linux-2.6/arch/x86/kernel/smpboot.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/smpboot.c
+++ linux-2.6/arch/x86/kernel/smpboot.c
@@ -1213,11 +1213,12 @@ __init void prefill_possible_map(void)
total_cpus = max_t(int, possible, num_processors + disabled_cpus);
- if (possible > CONFIG_NR_CPUS) {
+ /* nr_cpu_ids could be reduced via nr_cpus= */
+ if (possible > nr_cpu_ids) {
printk(KERN_WARNING
"%d Processors exceeds NR_CPUS limit of %d\n",
- possible, CONFIG_NR_CPUS);
- possible = CONFIG_NR_CPUS;
+ possible, nr_cpu_ids);
+ possible = nr_cpu_ids;
}
printk(KERN_INFO "SMP: Allowing %d CPUs, %d hotplug CPUs\n",
not sure it works again, could be bios fix the irq routing dest ?
tested that amd support logical flat too when cpus num <= 8 and even
bsp apic id > 8
so could remove vendor check...
Signed-off-by: Yinghai Lu <[email protected]>
---
arch/x86/kernel/apic/apic.c | 11 ++---------
arch/x86/kernel/apic/probe_64.c | 13 ++-----------
2 files changed, 4 insertions(+), 20 deletions(-)
Index: linux-2.6/arch/x86/kernel/apic/apic.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/apic/apic.c
+++ linux-2.6/arch/x86/kernel/apic/apic.c
@@ -1898,15 +1898,8 @@ void __cpuinit generic_processor_info(in
max_physical_apicid = apicid;
#ifdef CONFIG_X86_32
- switch (boot_cpu_data.x86_vendor) {
- case X86_VENDOR_INTEL:
- if (num_processors > 8)
- def_to_bigsmp = 1;
- break;
- case X86_VENDOR_AMD:
- if (max_physical_apicid >= 8)
- def_to_bigsmp = 1;
- }
+ if (num_processors > 8)
+ def_to_bigsmp = 1;
#endif
#if defined(CONFIG_SMP) || defined(CONFIG_X86_64)
Index: linux-2.6/arch/x86/kernel/apic/probe_64.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/apic/probe_64.c
+++ linux-2.6/arch/x86/kernel/apic/probe_64.c
@@ -67,17 +67,8 @@ void __init default_setup_apic_routing(v
}
#endif
- if (apic == &apic_flat) {
- switch (boot_cpu_data.x86_vendor) {
- case X86_VENDOR_INTEL:
- if (num_processors > 8)
- apic = &apic_physflat;
- break;
- case X86_VENDOR_AMD:
- if (max_physical_apicid >= 8)
- apic = &apic_physflat;
- }
- }
+ if (apic == &apic_flat && num_processors > 8)
+ apic = &apic_physflat;
printk(KERN_INFO "Setting APIC routing to %s\n", apic->name);
some systems that have disable cpus entries because same
BIOS will support 2 sockets and 4 sockets and more at
same time, BIOS just leave some disable entries, but
those system do not support cpu hotplug. we don't need
treat disabled_cpus as hotplug cpus.
so we can make nr_cpu_ids smaller and save more space
(pcpu data allocations), and could make some systems run
with logical flat instead of physical flat apic mode
-v2: change to black list instead
Signed-off-by: Yinghai Lu <[email protected]>
---
arch/x86/kernel/smpboot.c | 76 ++++++++++++++++++++++++++++++++++++++++++++--
1 file changed, 74 insertions(+), 2 deletions(-)
Index: linux-2.6/arch/x86/kernel/smpboot.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/smpboot.c
+++ linux-2.6/arch/x86/kernel/smpboot.c
@@ -47,6 +47,7 @@
#include <linux/bootmem.h>
#include <linux/err.h>
#include <linux/nmi.h>
+#include <linux/dmi.h>
#include <linux/tboot.h>
#include <asm/acpi.h>
@@ -1180,6 +1181,59 @@ static int __init _setup_possible_cpus(c
}
early_param("possible_cpus", _setup_possible_cpus);
+static __initdata int treat_disabled_cpus_as_hotplug = 1;
+static __init int hotplug_cpus_check(const struct dmi_system_id *d)
+{
+ printk(KERN_NOTICE "%s detected: treat disabled cpus as hotplug ones\n", d->ident);
+ treat_disabled_cpus_as_hotplug = 0;
+
+ return 0;
+}
+
+static struct dmi_system_id hotplug_cpus_dmi_table[] __initdata = {
+ {
+ .callback = hotplug_cpus_check,
+ .ident = "Sun Microsystems Sun Fire X4440",
+ .matches = {
+ DMI_MATCH(DMI_SYS_VENDOR, "Sun Microsystems"),
+ DMI_MATCH(DMI_PRODUCT_NAME, "Sun Fire X4440"),
+ },
+ },
+ {
+ .callback = hotplug_cpus_check,
+ .ident = "Sun Microsystems Sun Fire X4240",
+ .matches = {
+ DMI_MATCH(DMI_SYS_VENDOR, "Sun Microsystems"),
+ DMI_MATCH(DMI_PRODUCT_NAME, "Sun Fire X4240"),
+ },
+ },
+ {
+ .callback = hotplug_cpus_check,
+ .ident = "Sun Microsystems Sun Fire X4140",
+ .matches = {
+ DMI_MATCH(DMI_SYS_VENDOR, "Sun Microsystems"),
+ DMI_MATCH(DMI_PRODUCT_NAME, "Sun Fire X4140"),
+ },
+ },
+ {
+ .callback = hotplug_cpus_check,
+ .ident = "Sun Microsystems Sun Fire X4600",
+ .matches = {
+ DMI_MATCH(DMI_SYS_VENDOR, "Sun Microsystems"),
+ DMI_MATCH(DMI_PRODUCT_NAME, "Sun Fire X4600"),
+ },
+ },
+ {
+ .callback = hotplug_cpus_check,
+ .ident = "Sun Microsystems Sun Fire X4640",
+ .matches = {
+ DMI_MATCH(DMI_SYS_VENDOR, "Sun Microsystems"),
+ DMI_MATCH(DMI_PRODUCT_NAME, "Sun Fire X4640"),
+ },
+ },
+ { } /* NULL entry stops DMI scanning */
+};
+
/*
* cpu_possible_mask should be static, it cannot change as cpu's
@@ -1206,8 +1260,26 @@ __init void prefill_possible_map(void)
if (!num_processors)
num_processors = 1;
- if (setup_possible_cpus == -1)
- possible = num_processors + disabled_cpus;
+ if (setup_possible_cpus == -1) {
+ possible = num_processors;
+ /*
+ * do we have better way to detect hotplug cpus?
+ *
+ * some systems that have disable cpus entries because same
+ * BIOS will support 2 sockets and 4 sockets and more at
+ * same time, BIOS just leave some disabled entries with wild
+ * apicid, but those system do not support cpu hotplug.
+ * we don't need treat disabled_cpus as hotplug cpus.
+ * so we can make nr_cpu_ids smaller and save more space
+ * (pcpu data allocations), and could make some systems run
+ * with logical flat instead of physical flat apic mode
+ */
+ if (disabled_cpus) {
+ dmi_check_system(hotplug_cpus_dmi_table);
+ if (treat_disabled_cpus_as_hotplug)
+ possible += disabled_cpus;
+ }
+ }
else
possible = setup_possible_cpus;
should use nr_cpu_ids instead of num_processor, in case we have hotplug cpus.
if current only have 8 cpus is up, but if we will have more cpus that
will be hot added later, we should use physical flat at first.
nr_cpu_ids is the total cpus that could be supported.
-v2: per linus, chenage default_setup_apic_routing to _init, and call it for uni_processor
Signed-off-by: Yinghai Lu <[email protected]>
---
arch/x86/kernel/apic/apic.c | 2 --
arch/x86/kernel/apic/probe_32.c | 20 ++++++++++++++++++--
arch/x86/kernel/apic/probe_64.c | 3 ++-
arch/x86/kernel/smpboot.c | 2 --
4 files changed, 20 insertions(+), 7 deletions(-)
Index: linux-2.6/arch/x86/kernel/apic/probe_32.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/apic/probe_32.c
+++ linux-2.6/arch/x86/kernel/apic/probe_32.c
@@ -52,7 +52,7 @@ static int __init print_ipi_mode(void)
}
late_initcall(print_ipi_mode);
-void default_setup_apic_routing(void)
+static void local_default_setup_apic_routing(void)
{
#ifdef CONFIG_X86_IO_APIC
printk(KERN_INFO
@@ -103,7 +103,7 @@ struct apic apic_default = {
.init_apic_ldr = default_init_apic_ldr,
.ioapic_phys_id_map = default_ioapic_phys_id_map,
- .setup_apic_routing = default_setup_apic_routing,
+ .setup_apic_routing = local_default_setup_apic_routing,
.multi_timer_check = NULL,
.apicid_to_node = default_apicid_to_node,
.cpu_to_logical_apicid = default_cpu_to_logical_apicid,
@@ -207,6 +207,22 @@ void __init generic_bigsmp_probe(void)
apic = &apic_bigsmp;
printk(KERN_INFO "Overriding APIC driver with %s\n",
apic->name);
+ }
+ }
+#endif
+}
+
+void __init default_setup_apic_routing(void)
+{
+#ifdef CONFIG_X86_BIGSMP
+ /*
+ * make sure we go to bigsmp according to real nr_cpu_ids
+ */
+ if (!cmdline_apic && apic == &apic_default) {
+ if (nr_cpu_ids > 8) {
+ apic = &apic_bigsmp;
+ printk(KERN_INFO "Overriding APIC driver with %s\n",
+ apic->name);
}
}
#endif
Index: linux-2.6/arch/x86/kernel/smpboot.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/smpboot.c
+++ linux-2.6/arch/x86/kernel/smpboot.c
@@ -1084,9 +1084,7 @@ void __init native_smp_prepare_cpus(unsi
set_cpu_sibling_map(0);
enable_IR_x2apic();
-#ifdef CONFIG_X86_64
default_setup_apic_routing();
-#endif
if (smp_sanity_check(max_cpus) < 0) {
printk(KERN_INFO "SMP disabled\n");
Index: linux-2.6/arch/x86/kernel/apic/probe_64.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/apic/probe_64.c
+++ linux-2.6/arch/x86/kernel/apic/probe_64.c
@@ -67,7 +67,8 @@ void __init default_setup_apic_routing(v
}
#endif
- if (apic == &apic_flat && num_processors > 8)
+ /* not just num_processors, we could have hotplug cpus */
+ if (apic == &apic_flat && nr_cpu_ids > 8)
apic = &apic_physflat;
printk(KERN_INFO "Setting APIC routing to %s\n", apic->name);
Index: linux-2.6/arch/x86/kernel/apic/apic.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/apic/apic.c
+++ linux-2.6/arch/x86/kernel/apic/apic.c
@@ -1647,9 +1647,7 @@ int __init APIC_init_uniprocessor(void)
#endif
enable_IR_x2apic();
-#ifdef CONFIG_X86_64
default_setup_apic_routing();
-#endif
verify_local_APIC();
connect_bsp_APIC();
kill def_to_bigsmp
and move switch from default to bigsmp at default_setup_apic_routing...
so make default_setup_apic_routing more like 64 bit
also make the dmi relate code to be __init/__initdata
Signed-off-by: Yinghai Lu <[email protected]>
---
arch/x86/include/asm/apic.h | 3 -
arch/x86/include/asm/mpspec.h | 1
arch/x86/kernel/acpi/boot.c | 3 -
arch/x86/kernel/apic/apic.c | 5 --
arch/x86/kernel/apic/bigsmp_32.c | 48 -----------------------
arch/x86/kernel/apic/probe_32.c | 80 ++++++++++++++++++++-------------------
arch/x86/kernel/mpparse.c | 4 -
arch/x86/kernel/setup.c | 2
arch/x86/kernel/smpboot.c | 2
9 files changed, 46 insertions(+), 102 deletions(-)
Index: linux-2.6/arch/x86/include/asm/mpspec.h
===================================================================
--- linux-2.6.orig/arch/x86/include/asm/mpspec.h
+++ linux-2.6/arch/x86/include/asm/mpspec.h
@@ -23,7 +23,6 @@ extern int pic_mode;
#define MAX_IRQ_SOURCES 256
-extern unsigned int def_to_bigsmp;
extern u8 apicid_2_node[];
#ifdef CONFIG_X86_NUMAQ
Index: linux-2.6/arch/x86/kernel/apic/apic.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/apic/apic.c
+++ linux-2.6/arch/x86/kernel/apic/apic.c
@@ -1895,11 +1895,6 @@ void __cpuinit generic_processor_info(in
if (apicid > max_physical_apicid)
max_physical_apicid = apicid;
-#ifdef CONFIG_X86_32
- if (num_processors > 8)
- def_to_bigsmp = 1;
-#endif
-
#if defined(CONFIG_SMP) || defined(CONFIG_X86_64)
early_per_cpu(x86_cpu_to_apicid, cpu) = apicid;
early_per_cpu(x86_bios_cpu_apicid, cpu) = apicid;
Index: linux-2.6/arch/x86/kernel/apic/bigsmp_32.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/apic/bigsmp_32.c
+++ linux-2.6/arch/x86/kernel/apic/bigsmp_32.c
@@ -7,7 +7,6 @@
#include <linux/cpumask.h>
#include <linux/kernel.h>
#include <linux/init.h>
-#include <linux/dmi.h>
#include <linux/smp.h>
#include <asm/apicdef.h>
@@ -73,13 +72,6 @@ static void bigsmp_init_apic_ldr(void)
apic_write(APIC_LDR, val);
}
-static void bigsmp_setup_apic_routing(void)
-{
- printk(KERN_INFO
- "Enabling APIC mode: Physflat. Using %d I/O APICs\n",
- nr_ioapics);
-}
-
static int bigsmp_apicid_to_node(int logical_apicid)
{
return apicid_2_node[hard_smp_processor_id()];
@@ -154,52 +146,16 @@ static void bigsmp_send_IPI_all(int vect
bigsmp_send_IPI_mask(cpu_online_mask, vector);
}
-static int dmi_bigsmp; /* can be set by dmi scanners */
-
-static int hp_ht_bigsmp(const struct dmi_system_id *d)
-{
- printk(KERN_NOTICE "%s detected: force use of apic=bigsmp\n", d->ident);
- dmi_bigsmp = 1;
-
- return 0;
-}
-
-
-static const struct dmi_system_id bigsmp_dmi_table[] = {
- { hp_ht_bigsmp, "HP ProLiant DL760 G2",
- { DMI_MATCH(DMI_BIOS_VENDOR, "HP"),
- DMI_MATCH(DMI_BIOS_VERSION, "P44-"),
- }
- },
-
- { hp_ht_bigsmp, "HP ProLiant DL740",
- { DMI_MATCH(DMI_BIOS_VENDOR, "HP"),
- DMI_MATCH(DMI_BIOS_VERSION, "P47-"),
- }
- },
- { } /* NULL entry stops DMI scanning */
-};
-
static void bigsmp_vector_allocation_domain(int cpu, struct cpumask *retmask)
{
cpumask_clear(retmask);
cpumask_set_cpu(cpu, retmask);
}
-static int probe_bigsmp(void)
-{
- if (def_to_bigsmp)
- dmi_bigsmp = 1;
- else
- dmi_check_system(bigsmp_dmi_table);
-
- return dmi_bigsmp;
-}
-
struct apic apic_bigsmp = {
.name = "bigsmp",
- .probe = probe_bigsmp,
+ .probe = NULL,
.acpi_madt_oem_check = NULL,
.apic_id_registered = bigsmp_apic_id_registered,
@@ -217,7 +173,7 @@ struct apic apic_bigsmp = {
.init_apic_ldr = bigsmp_init_apic_ldr,
.ioapic_phys_id_map = bigsmp_ioapic_phys_id_map,
- .setup_apic_routing = bigsmp_setup_apic_routing,
+ .setup_apic_routing = NULL,
.multi_timer_check = NULL,
.apicid_to_node = bigsmp_apicid_to_node,
.cpu_to_logical_apicid = bigsmp_cpu_to_logical_apicid,
Index: linux-2.6/arch/x86/kernel/apic/probe_32.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/apic/probe_32.c
+++ linux-2.6/arch/x86/kernel/apic/probe_32.c
@@ -14,6 +14,8 @@
#include <linux/ctype.h>
#include <linux/init.h>
#include <linux/errno.h>
+#include <linux/dmi.h>
+
#include <asm/fixmap.h>
#include <asm/mpspec.h>
#include <asm/apicdef.h>
@@ -52,15 +54,6 @@ static int __init print_ipi_mode(void)
}
late_initcall(print_ipi_mode);
-static void local_default_setup_apic_routing(void)
-{
-#ifdef CONFIG_X86_IO_APIC
- printk(KERN_INFO
- "Enabling APIC mode: Flat. Using %d I/O APICs\n",
- nr_ioapics);
-#endif
-}
-
static void default_vector_allocation_domain(int cpu, struct cpumask *retmask)
{
/*
@@ -76,16 +69,10 @@ static void default_vector_allocation_do
cpumask_bits(retmask)[0] = APIC_ALL_CPUS;
}
-/* should be called last. */
-static int probe_default(void)
-{
- return 1;
-}
-
struct apic apic_default = {
.name = "default",
- .probe = probe_default,
+ .probe = NULL,
.acpi_madt_oem_check = NULL,
.apic_id_registered = default_apic_id_registered,
@@ -103,7 +90,7 @@ struct apic apic_default = {
.init_apic_ldr = default_init_apic_ldr,
.ioapic_phys_id_map = default_ioapic_phys_id_map,
- .setup_apic_routing = local_default_setup_apic_routing,
+ .setup_apic_routing = NULL,
.multi_timer_check = NULL,
.apicid_to_node = default_apicid_to_node,
.cpu_to_logical_apicid = default_cpu_to_logical_apicid,
@@ -192,24 +179,40 @@ static int __init parse_apic(char *arg)
}
early_param("apic", parse_apic);
-void __init generic_bigsmp_probe(void)
+static int dmi_bigsmp __initdata; /* can be set by dmi scanners */
+
+static int __init hp_ht_bigsmp(const struct dmi_system_id *d)
{
-#ifdef CONFIG_X86_BIGSMP
- /*
- * This routine is used to switch to bigsmp mode when
- * - There is no apic= option specified by the user
- * - generic_apic_probe() has chosen apic_default as the sub_arch
- * - we find more than 8 CPUs in acpi LAPIC listing with xAPIC support
- */
+ printk(KERN_NOTICE "%s detected: force use of apic=bigsmp\n", d->ident);
+ dmi_bigsmp = 1;
- if (!cmdline_apic && apic == &apic_default) {
- if (apic_bigsmp.probe()) {
- apic = &apic_bigsmp;
- printk(KERN_INFO "Overriding APIC driver with %s\n",
- apic->name);
+ return 0;
+}
+
+static struct dmi_system_id bigsmp_dmi_table[] __initdata = {
+ { hp_ht_bigsmp, "HP ProLiant DL760 G2",
+ { DMI_MATCH(DMI_BIOS_VENDOR, "HP"),
+ DMI_MATCH(DMI_BIOS_VERSION, "P44-"),
}
- }
+ },
+
+ { hp_ht_bigsmp, "HP ProLiant DL740",
+ { DMI_MATCH(DMI_BIOS_VENDOR, "HP"),
+ DMI_MATCH(DMI_BIOS_VERSION, "P47-"),
+ }
+ },
+ { } /* NULL entry stops DMI scanning */
+};
+
+static inline const char *get_apic_name(struct apic *apic)
+{
+ if (apic == &apic_default)
+ return "flat";
+#ifdef CONFIG_X86_BIGSMP
+ if (apic == &apic_bigsmp);
+ return "physical flat";
#endif
+ return apic->name;
}
void __init default_setup_apic_routing(void)
@@ -219,13 +222,19 @@ void __init default_setup_apic_routing(v
* make sure we go to bigsmp according to real nr_cpu_ids
*/
if (!cmdline_apic && apic == &apic_default) {
- if (nr_cpu_ids > 8) {
+ dmi_check_system(bigsmp_dmi_table);
+ if (nr_cpu_ids > 8 || dmi_bigsmp) {
apic = &apic_bigsmp;
printk(KERN_INFO "Overriding APIC driver with %s\n",
- apic->name);
+ get_apic_name(apic));
}
}
#endif
+#ifdef CONFIG_X86_IO_APIC
+ printk(KERN_INFO
+ "Enabling APIC mode: %s. Using %d I/O APICs\n",
+ get_apic_name(apic), nr_ioapics);
+#endif
}
void __init generic_apic_probe(void)
@@ -233,14 +242,11 @@ void __init generic_apic_probe(void)
if (!cmdline_apic) {
int i;
for (i = 0; apic_probe[i]; i++) {
- if (apic_probe[i]->probe()) {
+ if (apic_probe[i]->probe && apic_probe[i]->probe()) {
apic = apic_probe[i];
break;
}
}
- /* Not visible without early console */
- if (!apic_probe[i])
- panic("Didn't find an APIC driver");
}
printk(KERN_INFO "Using APIC driver %s\n", apic->name);
}
Index: linux-2.6/arch/x86/kernel/setup.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/setup.c
+++ linux-2.6/arch/x86/kernel/setup.c
@@ -184,8 +184,6 @@ static void set_mca_bus(int x)
#endif
}
-unsigned int def_to_bigsmp;
-
/* for MCA, but anyone else can use it if they want */
unsigned int machine_id;
unsigned int machine_submodel_id;
Index: linux-2.6/arch/x86/kernel/smpboot.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/smpboot.c
+++ linux-2.6/arch/x86/kernel/smpboot.c
@@ -947,7 +947,7 @@ static int __init smp_sanity_check(unsig
preempt_disable();
#if !defined(CONFIG_X86_BIGSMP) && defined(CONFIG_X86_32)
- if (def_to_bigsmp && nr_cpu_ids > 8) {
+ if (apic == &apic_default && nr_cpu_ids > 8) {
unsigned int cpu;
unsigned nr;
Index: linux-2.6/arch/x86/include/asm/apic.h
===================================================================
--- linux-2.6.orig/arch/x86/include/asm/apic.h
+++ linux-2.6/arch/x86/include/asm/apic.h
@@ -456,9 +456,6 @@ static inline void default_wait_for_init
return;
}
-extern void generic_bigsmp_probe(void);
-
-
#ifdef CONFIG_X86_LOCAL_APIC
#include <asm/smp.h>
Index: linux-2.6/arch/x86/kernel/acpi/boot.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/acpi/boot.c
+++ linux-2.6/arch/x86/kernel/acpi/boot.c
@@ -1185,9 +1185,6 @@ static void __init acpi_process_madt(voi
if (!error) {
acpi_lapic = 1;
-#ifdef CONFIG_X86_BIGSMP
- generic_bigsmp_probe();
-#endif
/*
* Parse MADT IO-APIC entries
*/
Index: linux-2.6/arch/x86/kernel/mpparse.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/mpparse.c
+++ linux-2.6/arch/x86/kernel/mpparse.c
@@ -359,10 +359,6 @@ static int __init smp_read_mpc(struct mp
x86_init.mpparse.mpc_record(1);
}
-#ifdef CONFIG_X86_BIGSMP
- generic_bigsmp_probe();
-#endif
-
if (apic->setup_apic_routing)
apic->setup_apic_routing();
On Tue, 12 Jan 2010, Yinghai Lu wrote:
> on x86, before prefill_possible_map(), nr_cpu_ids will be NR_CPUS aka CONFIG_NR_CPUS
>
> add nr_cpus= to set nr_cpu_ids. so we can simulate cpus <=8 on normal config.
> instead of change NR_CPUS directly.
We already have
maxcpus=x?
Why do we need this twice?
On Tue, Jan 12, 2010 at 11:32 AM, Christoph Lameter
<[email protected]> wrote:
>
> On Tue, 12 Jan 2010, Yinghai Lu wrote:
>
>> on x86, before prefill_possible_map(), nr_cpu_ids will be NR_CPUS aka CONFIG_NR_CPUS
>>
>> add nr_cpus= to set nr_cpu_ids. so we can simulate cpus <=8 on normal config.
>> instead of change NR_CPUS directly.
>
> We already have
>
> maxcpus=x?
>
> Why do we need this twice?
maxcpus only change setup_max_cpus., and if you are using maxcpus=1,
and you have 8 cpus installed, you can put other
cpus back online via /sys/interface.
nr_cpus= is hard limit nr_cpu_ids, so if you have 16 cpus installed,
nr_cpus=8 will make your nr_cpu_ids=8, and you can not put back
other 8 back. and apic mode could stay with logical flat.
this is used to simulate some debug case. for example you have kernel
support physflat, and flat, with CONFIG_NR_CPUS=255. to run that on
system that only have 8 cpus, you will have apic mode in logical flat.
but if you have run the kernel on system with 32 cpus installed, it
will switch to physflat even you have maxcpus=8 appedded.
YH
On Tue, 12 Jan 2010, Yinghai Lu wrote:
> > Why do we need this twice?
>
> maxcpus only change setup_max_cpus., and if you are using maxcpus=1,
> and you have 8 cpus installed, you can put other
> cpus back online via /sys/interface.
Hmmm.. Strange semantics since maxcpus=0 disables smp completely. No cpu
can be activated later. Similar to nr_cpus ?
> nr_cpus= is hard limit nr_cpu_ids, so if you have 16 cpus installed,
> nr_cpus=8 will make your nr_cpu_ids=8, and you can not put back
> other 8 back. and apic mode could stay with logical flat.
> this is used to simulate some debug case. for example you have kernel
> support physflat, and flat, with CONFIG_NR_CPUS=255. to run that on
> system that only have 8 cpus, you will have apic mode in logical flat.
> but if you have run the kernel on system with 32 cpus installed, it
> will switch to physflat even you have maxcpus=8 appedded.
Ok makes sense.
Trouble is that NR_CPUS is used all over the place. If nr_cpu_ids <
NR_CPUS at boot then there is a danger of for loops to NR_CPUS going out
of
bounds.
CONFIG_NR_CPUS is used for various bitmaps so that seems to be
okay.
drivers/acpi/numa.c:acpi_numa_init probably should use nr_cpu_ids
instead now.
There is an octeon driver in staging that has some issues with NR_CPUS as
well.
On Tue, 12 Jan 2010, Christoph Lameter wrote:
>
> Trouble is that NR_CPUS is used all over the place. If nr_cpu_ids <
> NR_CPUS at boot then there is a danger of for loops to NR_CPUS going out
> of bounds.
>
> CONFIG_NR_CPUS is used for various bitmaps so that seems to be okay.
>
> drivers/acpi/numa.c:acpi_numa_init probably should use nr_cpu_ids
> instead now.
>
> There is an octeon driver in staging that has some issues with NR_CPUS
> as well.
I suspect that this is the real reason for the current behavior of
'maxcpus=', and that if all of those issues get fixed we could probably
make maxcpus do what Yinghai's new 'nr_cpus=' does.
So in a perfect world, CONFIG_NR_CPUS's would never really be used, except
for some fundamental static allocations/limits that are too painful to try
to make dynamic.
I doubt that anybody really _cares_ about the "you can add them later"
behavior of the current maxcpus thing, and I suspect that the nr_cpus
semantics is what people generally would have expected.
Linus
On Tue, Jan 12, 2010 at 12:31 PM, Christoph Lameter
<[email protected]> wrote:
> On Tue, 12 Jan 2010, Yinghai Lu wrote:
>
>> > Why do we need this twice?
>>
>> maxcpus only change setup_max_cpus., and if you are using maxcpus=1,
>> and you have 8 cpus installed, you can put other
>> cpus back online via /sys/interface.
>
> Hmmm.. Strange semantics since maxcpus=0 disables smp completely. No cpu
> can be activated later. Similar to nr_cpus ?
no
for SMP kernel, when nr_cpus=1 is specified, it looks like only one
cpu is installed physically.
smp is still enabled.
maxcpus=0 is really caused misunderstanding.
other maxcpus=1 and other should be rename to boot_online_cpus=
>
>> nr_cpus= is hard limit nr_cpu_ids, so if you have 16 cpus installed,
>> nr_cpus=8 will make your nr_cpu_ids=8, and you can not put back
>> other 8 back. and apic mode could stay with logical flat.
>> this is used to simulate some debug case. for example you have kernel
>> support physflat, and flat, with CONFIG_NR_CPUS=255. to run that on
>> system that only have 8 cpus, you will have apic mode in logical flat.
>> ?but if you have run the kernel on system with 32 cpus installed, it
>> will switch to physflat even you have maxcpus=8 appedded.
>
> Ok makes sense.
good.
YH
On Tue, Jan 12, 2010 at 12:48 PM, Christoph Lameter
<[email protected]> wrote:
> Trouble is that NR_CPUS is used all over the place. If nr_cpu_ids <
> NR_CPUS at boot then there is a danger of for loops to NR_CPUS going out
> of
> bounds.
>
> CONFIG_NR_CPUS is used for various bitmaps so that seems to be
> okay.
cpumask_var?
>
> drivers/acpi/numa.c:acpi_numa_init probably should use nr_cpu_ids
> instead now.
before prefill_possible_map for x86
before setup_nr_cpu_ids for other platform
nr_cpu_ids = NR_CPUS = CONFIG_NR_CPUS
>
> There is an octeon driver in staging that has some issues with NR_CPUS as
> well.
>
that should be fixed, we should use nr_cpu_ids instead for them.
YH
On Tue, Jan 12, 2010 at 12:48 PM, Christoph Lameter
<[email protected]> wrote:
>
> drivers/acpi/numa.c:acpi_numa_init probably should use nr_cpu_ids
> instead now.
you are right.
YH