Re: [Patch] sched: new sched domain for representing multi-core

From: Siddha, Suresh B
Date: Mon Jan 30 2006 - 20:26:54 EST

On Fri, Jan 27, 2006 at 04:00:19PM -0800, Andrew Morton wrote:
> Perhaps we should just make SMT and MC disjoint in Kconfig. Your call.

No. SMT and MC are not disjoint.

> I'll duck the patch for now.

Appended a new patch with all the feedback incorporated. Please apply.

thanks,
suresh

--
Appended patch adds a new sched domain for representing multi-core with
shared caches between cores. Consider a dual package system, each package
containing two cores and with last level cache shared between cores with in a
package. If there are two runnable processes, with this appended patch
those two processes will be scheduled on different packages.

On such system, with this patch we have observed 8% perf improvement with
specJBB(2 warehouse) benchmark and 35% improvement with CFP2000 rate(with
2 users).

This new domain will come into play only on multi-core systems with shared
caches. On other systems, this sched domain will be removed by
domain degeneration code. This new domain can be also used for implementing
power savings policy (see OLS 2005 CMP kernel scheduler paper for more
details.. I will post another patch for power savings policy soon)

Most of the arch/* file changes are for cpu_coregroup_map() implementation.

Signed-off-by: Suresh Siddha <suresh.b.siddha@xxxxxxxxx>

diff -pNru linux-2.6.16-rc1/arch/i386/Kconfig linux-core/arch/i386/Kconfig
--- linux-2.6.16-rc1/arch/i386/Kconfig 2006-01-16 23:44:47.000000000 -0800
+++ linux-core/arch/i386/Kconfig 2006-01-26 18:11:47.370042152 -0800
@@ -235,6 +235,14 @@ config SCHED_SMT
cost of slightly increased overhead in some places. If unsure say
N here.

+config SCHED_MC
+ bool "Multi-core scheduler support"
+ depends on SMP
+ help
+ Multi-core scheduler support improves the CPU scheduler's decision
+ making when dealing with multi-core CPU chips at a cost of slightly
+ increased overhead in some places. If unsure say N here.
+
source "kernel/Kconfig.preempt"

config X86_UP_APIC
diff -pNru linux-2.6.16-rc1/arch/i386/kernel/cpu/common.c linux-core/arch/i386/kernel/cpu/common.c
--- linux-2.6.16-rc1/arch/i386/kernel/cpu/common.c 2006-01-16 23:44:47.000000000 -0800
+++ linux-core/arch/i386/kernel/cpu/common.c 2006-01-30 15:08:00.680167856 -0800
@@ -244,7 +244,7 @@ static void __init early_cpu_detect(void
void __devinit generic_identify(struct cpuinfo_x86 * c)
{
u32 tfms, xlvl;
- int junk;
+ int ebx;

if (have_cpuid_p()) {
/* Get vendor name */
@@ -260,7 +260,7 @@ void __devinit generic_identify(struct c
/* Intel-defined flags: level 0x00000001 */
if ( c->cpuid_level >= 0x00000001 ) {
u32 capability, excap;
- cpuid(0x00000001, &tfms, &junk, &excap, &capability);
+ cpuid(0x00000001, &tfms, &ebx, &excap, &capability);
c->x86_capability[0] = capability;
c->x86_capability[4] = excap;
c->x86 = (tfms >> 8) & 15;
@@ -270,6 +270,11 @@ void __devinit generic_identify(struct c
c->x86_model += ((tfms >> 16) & 0xF) << 4;
}
c->x86_mask = tfms & 15;
+#ifdef CONFIG_SMP
+ c->apicid = phys_pkg_id((ebx >> 24) & 0xFF, 0);
+#else
+ c->apicid = (ebx >> 24) & 0xFF;
+#endif
} else {
/* Have CPUID level 0 only - unheard of */
c->x86 = 4;
@@ -448,7 +453,6 @@ void __devinit detect_ht(struct cpuinfo_

cpuid(1, &eax, &ebx, &ecx, &edx);

- c->apicid = phys_pkg_id((ebx >> 24) & 0xFF, 0);

if (!cpu_has(c, X86_FEATURE_HT) || cpu_has(c, X86_FEATURE_CMP_LEGACY))
return;
diff -pNru linux-2.6.16-rc1/arch/i386/kernel/cpu/intel_cacheinfo.c linux-core/arch/i386/kernel/cpu/intel_cacheinfo.c
--- linux-2.6.16-rc1/arch/i386/kernel/cpu/intel_cacheinfo.c 2006-01-16 23:44:47.000000000 -0800
+++ linux-core/arch/i386/kernel/cpu/intel_cacheinfo.c 2006-01-24 14:38:36.361164048 -0800
@@ -161,6 +161,10 @@ unsigned int __cpuinit init_intel_cachei
unsigned int trace = 0, l1i = 0, l1d = 0, l2 = 0, l3 = 0; /* Cache sizes */
unsigned int new_l1d = 0, new_l1i = 0; /* Cache sizes from cpuid(4) */
unsigned int new_l2 = 0, new_l3 = 0, i; /* Cache sizes from cpuid(4) */
+ unsigned int l2_id = 0, l3_id = 0, num_threads_sharing, index_msb;
+#ifdef CONFIG_SMP
+ unsigned int cpu = (c == &boot_cpu_data) ? 0 : (c - cpu_data);
+#endif

if (c->cpuid_level > 4) {
static int is_initialized;
@@ -193,9 +197,15 @@ unsigned int __cpuinit init_intel_cachei
break;
case 2:
new_l2 = this_leaf.size/1024;
+ num_threads_sharing = 1 + this_leaf.eax.split.num_threads_sharing;
+ index_msb = get_count_order(num_threads_sharing);
+ l2_id = c->apicid >> index_msb;
break;
case 3:
new_l3 = this_leaf.size/1024;
+ num_threads_sharing = 1 + this_leaf.eax.split.num_threads_sharing;
+ index_msb = get_count_order(num_threads_sharing);
+ l3_id = c->apicid >> index_msb;
break;
default:
break;
@@ -261,11 +271,19 @@ unsigned int __cpuinit init_intel_cachei
if (new_l1i)
l1i = new_l1i;

- if (new_l2)
+ if (new_l2) {
l2 = new_l2;
+#ifdef CONFIG_SMP
+ cpu_llc_id[cpu] = l2_id;
+#endif
+ }

- if (new_l3)
+ if (new_l3) {
l3 = new_l3;
+#ifdef CONFIG_SMP
+ cpu_llc_id[cpu] = l3_id;
+#endif
+ }

if ( trace )
printk (KERN_INFO "CPU: Trace cache: %dK uops", trace);
diff -pNru linux-2.6.16-rc1/arch/i386/kernel/smpboot.c linux-core/arch/i386/kernel/smpboot.c
--- linux-2.6.16-rc1/arch/i386/kernel/smpboot.c 2006-01-16 23:44:47.000000000 -0800
+++ linux-core/arch/i386/kernel/smpboot.c 2006-01-30 14:36:45.290270456 -0800
@@ -72,6 +72,9 @@ int phys_proc_id[NR_CPUS] __read_mostly
/* Core ID of each logical CPU */
int cpu_core_id[NR_CPUS] __read_mostly = {[0 ... NR_CPUS-1] = BAD_APICID};

+/* Last level cache ID of each logical CPU */
+int cpu_llc_id[NR_CPUS] __cpuinitdata = {[0 ... NR_CPUS-1] = BAD_APICID};
+
/* representing HT siblings of each logical CPU */
cpumask_t cpu_sibling_map[NR_CPUS] __read_mostly;
EXPORT_SYMBOL(cpu_sibling_map);
@@ -444,6 +447,18 @@ static void __devinit smp_callin(void)

static int cpucount;

+/* maps the cpu to the sched domain representing multi-core */
+cpumask_t cpu_coregroup_map(int cpu)
+{
+ struct cpuinfo_x86 *c = cpu_data + cpu;
+ /*
+ * For perf, we return last level cache shared map.
+ * TBD: when power saving sched policy is added, we will return
+ * cpu_core_map when power saving policy is enabled
+ */
+ return c->llc_shared_map;
+}
+
/* representing cpus for which sibling maps can be computed */
static cpumask_t cpu_sibling_setup_map;

@@ -463,12 +478,16 @@ set_cpu_sibling_map(int cpu)
cpu_set(cpu, cpu_sibling_map[i]);
cpu_set(i, cpu_core_map[cpu]);
cpu_set(cpu, cpu_core_map[i]);
+ cpu_set(i, c[cpu].llc_shared_map);
+ cpu_set(cpu, c[i].llc_shared_map);
}
}
} else {
cpu_set(cpu, cpu_sibling_map[cpu]);
}

+ cpu_set(cpu, c[cpu].llc_shared_map);
+
if (current_cpu_data.x86_max_cores == 1) {
cpu_core_map[cpu] = cpu_sibling_map[cpu];
c[cpu].booted_cores = 1;
@@ -476,6 +495,11 @@ set_cpu_sibling_map(int cpu)
}

for_each_cpu_mask(i, cpu_sibling_setup_map) {
+ if (cpu_llc_id[cpu] != BAD_APICID &&
+ cpu_llc_id[cpu] == cpu_llc_id[i]) {
+ cpu_set(i, c[cpu].llc_shared_map);
+ cpu_set(cpu, c[i].llc_shared_map);
+ }
if (phys_proc_id[cpu] == phys_proc_id[i]) {
cpu_set(i, cpu_core_map[cpu]);
cpu_set(cpu, cpu_core_map[i]);
diff -pNru linux-2.6.16-rc1/arch/x86_64/Kconfig linux-core/arch/x86_64/Kconfig
--- linux-2.6.16-rc1/arch/x86_64/Kconfig 2006-01-16 23:44:47.000000000 -0800
+++ linux-core/arch/x86_64/Kconfig 2006-01-26 18:21:15.432683504 -0800
@@ -246,6 +246,14 @@ config SCHED_SMT
cost of slightly increased overhead in some places. If unsure say
N here.

+config SCHED_MC
+ bool "Multi-core scheduler support"
+ depends on SMP
+ help
+ Multi-core scheduler support improves the CPU scheduler's decision
+ making when dealing with multi-core CPU chips at a cost of slightly
+ increased overhead in some places. If unsure say N here.
+
source "kernel/Kconfig.preempt"

config NUMA
diff -pNru linux-2.6.16-rc1/arch/x86_64/kernel/setup.c linux-core/arch/x86_64/kernel/setup.c
--- linux-2.6.16-rc1/arch/x86_64/kernel/setup.c 2006-01-16 23:44:47.000000000 -0800
+++ linux-core/arch/x86_64/kernel/setup.c 2006-01-24 13:35:49.181862352 -0800
@@ -935,7 +935,6 @@ static void __cpuinit detect_ht(struct c

cpuid(1, &eax, &ebx, &ecx, &edx);

- c->apicid = phys_pkg_id(0);

if (!cpu_has(c, X86_FEATURE_HT) || cpu_has(c, X86_FEATURE_CMP_LEGACY))
return;
@@ -1144,6 +1143,8 @@ void __cpuinit identify_cpu(struct cpuin
c->x86_capability[2] = cpuid_edx(0x80860001);
}

+ c->apicid = phys_pkg_id(0);
+
/*
* Vendor-specific initialization. In this section we
* canonicalize the feature flags, meaning if there are
diff -pNru linux-2.6.16-rc1/arch/x86_64/kernel/smpboot.c linux-core/arch/x86_64/kernel/smpboot.c
--- linux-2.6.16-rc1/arch/x86_64/kernel/smpboot.c 2006-01-16 23:44:47.000000000 -0800
+++ linux-core/arch/x86_64/kernel/smpboot.c 2006-01-27 18:06:48.607664448 -0800
@@ -67,6 +67,9 @@ u8 phys_proc_id[NR_CPUS] __read_mostly =
/* core ID of each logical CPU */
u8 cpu_core_id[NR_CPUS] __read_mostly = { [0 ... NR_CPUS-1] = BAD_APICID };

+/* Last level cache ID of each logical CPU */
+u8 cpu_llc_id[NR_CPUS] __cpuinitdata = {[0 ... NR_CPUS-1] = BAD_APICID};
+
/* Bitmask of currently online CPUs */
cpumask_t cpu_online_map __read_mostly;

@@ -444,6 +447,18 @@ void __cpuinit smp_callin(void)
cpu_set(cpuid, cpu_callin_map);
}

+/* maps the cpu to the sched domain representing multi-core */
+cpumask_t cpu_coregroup_map(int cpu)
+{
+ struct cpuinfo_x86 *c = cpu_data + cpu;
+ /*
+ * For perf, we return last level cache shared map.
+ * TBD: when power saving sched policy is added, we will return
+ * cpu_core_map when power saving policy is enabled
+ */
+ return c->llc_shared_map;
+}
+
/* representing cpus for which sibling maps can be computed */
static cpumask_t cpu_sibling_setup_map;

@@ -462,12 +477,16 @@ static inline void set_cpu_sibling_map(i
cpu_set(cpu, cpu_sibling_map[i]);
cpu_set(i, cpu_core_map[cpu]);
cpu_set(cpu, cpu_core_map[i]);
+ cpu_set(i, c[cpu].llc_shared_map);
+ cpu_set(cpu, c[i].llc_shared_map);
}
}
} else {
cpu_set(cpu, cpu_sibling_map[cpu]);
}

+ cpu_set(cpu, c[cpu].llc_shared_map);
+
if (current_cpu_data.x86_max_cores == 1) {
cpu_core_map[cpu] = cpu_sibling_map[cpu];
c[cpu].booted_cores = 1;
@@ -475,6 +494,11 @@ static inline void set_cpu_sibling_map(i
}

for_each_cpu_mask(i, cpu_sibling_setup_map) {
+ if (cpu_llc_id[cpu] != BAD_APICID &&
+ cpu_llc_id[cpu] == cpu_llc_id[i]) {
+ cpu_set(i, c[cpu].llc_shared_map);
+ cpu_set(cpu, c[i].llc_shared_map);
+ }
if (phys_proc_id[cpu] == phys_proc_id[i]) {
cpu_set(i, cpu_core_map[cpu]);
cpu_set(cpu, cpu_core_map[i]);
diff -pNru linux-2.6.16-rc1/include/asm-i386/processor.h linux-core/include/asm-i386/processor.h
--- linux-2.6.16-rc1/include/asm-i386/processor.h 2006-01-16 23:44:47.000000000 -0800
+++ linux-core/include/asm-i386/processor.h 2006-01-30 15:20:41.619487496 -0800
@@ -20,6 +20,7 @@
#include <linux/config.h>
#include <linux/threads.h>
#include <asm/percpu.h>
+#include <linux/cpumask.h>

/* flag for disabling the tsc */
extern int tsc_disable;
@@ -67,6 +68,9 @@ struct cpuinfo_x86 {
char pad0;
int x86_power;
unsigned long loops_per_jiffy;
+#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 booted_cores; /* number of cores as seen by OS */
unsigned char apicid;
@@ -103,6 +107,7 @@ extern struct cpuinfo_x86 cpu_data[];

extern int phys_proc_id[NR_CPUS];
extern int cpu_core_id[NR_CPUS];
+extern int cpu_llc_id[NR_CPUS];
extern char ignore_fpu_irq;

extern void identify_cpu(struct cpuinfo_x86 *);
diff -pNru linux-2.6.16-rc1/include/asm-i386/topology.h linux-core/include/asm-i386/topology.h
--- linux-2.6.16-rc1/include/asm-i386/topology.h 2006-01-16 23:44:47.000000000 -0800
+++ linux-core/include/asm-i386/topology.h 2006-01-24 13:43:46.379317312 -0800
@@ -103,4 +103,6 @@ extern unsigned long node_remap_size[];

#endif /* CONFIG_NUMA */

+extern cpumask_t cpu_coregroup_map(int cpu);
+
#endif /* _ASM_I386_TOPOLOGY_H */
diff -pNru linux-2.6.16-rc1/include/asm-x86_64/processor.h linux-core/include/asm-x86_64/processor.h
--- linux-2.6.16-rc1/include/asm-x86_64/processor.h 2006-01-16 23:44:47.000000000 -0800
+++ linux-core/include/asm-x86_64/processor.h 2006-01-30 15:21:19.685700552 -0800
@@ -20,6 +20,7 @@
#include <asm/mmsegment.h>
#include <asm/percpu.h>
#include <linux/personality.h>
+#include <linux/cpumask.h>

#define TF_MASK 0x00000100
#define IF_MASK 0x00000200
@@ -65,6 +66,9 @@ struct cpuinfo_x86 {
__u32 x86_power;
__u32 extended_cpuid_level; /* Max extended CPUID function supported */
unsigned long loops_per_jiffy;
+#ifdef CONFIG_SMP
+ cpumask_t llc_shared_map; /* cpus sharing the last level cache */
+#endif
__u8 apicid;
__u8 booted_cores; /* number of cores as seen by OS */
} ____cacheline_aligned;
diff -pNru linux-2.6.16-rc1/include/asm-x86_64/smp.h linux-core/include/asm-x86_64/smp.h
--- linux-2.6.16-rc1/include/asm-x86_64/smp.h 2006-01-16 23:44:47.000000000 -0800
+++ linux-core/include/asm-x86_64/smp.h 2006-01-27 18:06:21.385802800 -0800
@@ -56,6 +56,7 @@ extern cpumask_t cpu_sibling_map[NR_CPUS
extern cpumask_t cpu_core_map[NR_CPUS];
extern u8 phys_proc_id[NR_CPUS];
extern u8 cpu_core_id[NR_CPUS];
+extern u8 cpu_llc_id[NR_CPUS];

#define SMP_TRAMPOLINE_BASE 0x6000

diff -pNru linux-2.6.16-rc1/include/asm-x86_64/topology.h linux-core/include/asm-x86_64/topology.h
--- linux-2.6.16-rc1/include/asm-x86_64/topology.h 2006-01-16 23:44:47.000000000 -0800
+++ linux-core/include/asm-x86_64/topology.h 2006-01-24 13:43:57.069692128 -0800
@@ -59,4 +59,6 @@ extern int __node_distance(int, int);

#include <asm-generic/topology.h>

+extern cpumask_t cpu_coregroup_map(int cpu);
+
#endif
diff -pNru linux-2.6.16-rc1/include/linux/topology.h linux-core/include/linux/topology.h
--- linux-2.6.16-rc1/include/linux/topology.h 2006-01-16 23:44:47.000000000 -0800
+++ linux-core/include/linux/topology.h 2006-01-25 21:10:50.380652784 -0800
@@ -156,6 +156,15 @@
.nr_balance_failed = 0, \
}

+#ifdef CONFIG_SCHED_MC
+#ifndef SD_MC_INIT
+/* for now its same as SD_CPU_INIT.
+ * TBD: Tune Domain parameters!
+ */
+#define SD_MC_INIT SD_CPU_INIT
+#endif
+#endif
+
#ifdef CONFIG_NUMA
#ifndef SD_NODE_INIT
#error Please define an appropriate SD_NODE_INIT in include/asm/topology.h!!!
diff -pNru linux-2.6.16-rc1/kernel/sched.c linux-core/kernel/sched.c
--- linux-2.6.16-rc1/kernel/sched.c 2006-01-28 17:13:20.837523144 -0800
+++ linux-core/kernel/sched.c 2006-01-30 15:52:45.531008488 -0800
@@ -5658,11 +5658,31 @@ static int cpu_to_cpu_group(int cpu)
}
#endif

+#ifdef CONFIG_SCHED_MC
+static DEFINE_PER_CPU(struct sched_domain, core_domains);
+static struct sched_group sched_group_core[NR_CPUS];
+#endif
+
+#if defined(CONFIG_SCHED_MC) && defined(CONFIG_SCHED_MT)
+static int cpu_to_core_group(int cpu)
+{
+ return first_cpu(cpu_sibling_map[cpu]);
+}
+#elif defined(CONFIG_SCHED_MC)
+static int cpu_to_core_group(int cpu)
+{
+ return cpu;
+}
+#endif
+
static DEFINE_PER_CPU(struct sched_domain, phys_domains);
static struct sched_group sched_group_phys[NR_CPUS];
static int cpu_to_phys_group(int cpu)
{
-#ifdef CONFIG_SCHED_SMT
+#if defined(CONFIG_SCHED_MC)
+ cpumask_t mask = cpu_coregroup_map(cpu);
+ return first_cpu(mask);
+#elif defined(CONFIG_SCHED_MT)
return first_cpu(cpu_sibling_map[cpu]);
#else
return cpu;
@@ -5760,6 +5780,17 @@ void build_sched_domains(const cpumask_t
sd->parent = p;
sd->groups = &sched_group_phys[group];

+#ifdef CONFIG_SCHED_MC
+ p = sd;
+ sd = &per_cpu(core_domains, i);
+ group = cpu_to_core_group(i);
+ *sd = SD_MC_INIT;
+ sd->span = cpu_coregroup_map(i);
+ cpus_and(sd->span, sd->span, *cpu_map);
+ sd->parent = p;
+ sd->groups = &sched_group_core[group];
+#endif
+
#ifdef CONFIG_SCHED_SMT
p = sd;
sd = &per_cpu(cpu_domains, i);
@@ -5785,6 +5816,19 @@ void build_sched_domains(const cpumask_t
}
#endif

+#ifdef CONFIG_SCHED_MC
+ /* Set up multi-core groups */
+ for_each_cpu_mask(i, *cpu_map) {
+ cpumask_t this_core_map = cpu_coregroup_map(i);
+ cpus_and(this_core_map, this_core_map, *cpu_map);
+ if (i != first_cpu(this_core_map))
+ continue;
+ init_sched_build_groups(sched_group_core, this_core_map,
+ &cpu_to_core_group);
+ }
+#endif
+
+
/* Set up physical groups */
for (i = 0; i < MAX_NUMNODES; i++) {
cpumask_t nodemask = node_to_cpumask(i);
@@ -5881,11 +5925,31 @@ void build_sched_domains(const cpumask_t
power = SCHED_LOAD_SCALE;
sd->groups->cpu_power = power;
#endif
+#ifdef CONFIG_SCHED_MC
+ sd = &per_cpu(core_domains, i);
+ power = SCHED_LOAD_SCALE + (cpus_weight(sd->groups->cpumask)-1)
+ * SCHED_LOAD_SCALE / 10;
+ sd->groups->cpu_power = power;
+
+ sd = &per_cpu(phys_domains, i);

+ /*
+ * This has to be < 2 * SCHED_LOAD_SCALE
+ * Lets keep it SCHED_LOAD_SCALE, so that
+ * while calculating NUMA group's cpu_power
+ * we can simply do
+ * numa_group->cpu_power += phys_group->cpu_power;
+ *
+ * See "only add power once for each physical pkg"
+ * comment below
+ */
+ sd->groups->cpu_power = SCHED_LOAD_SCALE;
+#else
sd = &per_cpu(phys_domains, i);
power = SCHED_LOAD_SCALE + SCHED_LOAD_SCALE *
(cpus_weight(sd->groups->cpumask)-1) / 10;
sd->groups->cpu_power = power;
+#endif

#ifdef CONFIG_NUMA
sd = &per_cpu(allnodes_domains, i);
@@ -5907,7 +5971,6 @@ void build_sched_domains(const cpumask_t
next_sg:
for_each_cpu_mask(j, sg->cpumask) {
struct sched_domain *sd;
- int power;

sd = &per_cpu(phys_domains, j);
if (j != first_cpu(sd->groups->cpumask)) {
@@ -5917,10 +5980,8 @@ next_sg:
*/
continue;
}
- power = SCHED_LOAD_SCALE + SCHED_LOAD_SCALE *
- (cpus_weight(sd->groups->cpumask)-1) / 10;

- sg->cpu_power += power;
+ sg->cpu_power += sd->groups->cpu_power;
}
sg = sg->next;
if (sg != sched_group_nodes[i])
@@ -5933,6 +5994,8 @@ next_sg:
struct sched_domain *sd;
#ifdef CONFIG_SCHED_SMT
sd = &per_cpu(cpu_domains, i);
+#elif defined(CONFIG_SCHED_MC)
+ sd = &per_cpu(core_domains, i);
#else
sd = &per_cpu(phys_domains, i);
#endif
-
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