[MIPS] MT: Scheduler support for SMT
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index 11bc17c..d5a89f3 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -1442,6 +1442,7 @@
select MIPS_MT
select NR_CPUS_DEFAULT_2
select SMP
+ select SYS_SUPPORTS_SCHED_SMT if SMP
select SYS_SUPPORTS_SMP
help
This is a kernel model which is also known a VSMP or lately
@@ -1468,6 +1469,19 @@
config MIPS_MT
bool
+config SCHED_SMT
+ bool "SMT (multithreading) scheduler support"
+ depends on SYS_SUPPORTS_SCHED_SMT
+ default n
+ help
+ SMT scheduler support improves the CPU scheduler's decision making
+ when dealing with MIPS MT enabled cores at a cost of slightly
+ increased overhead in some places. If unsure say N here.
+
+config SYS_SUPPORTS_SCHED_SMT
+ bool
+
+
config SYS_SUPPORTS_MULTITHREADING
bool
diff --git a/arch/mips/kernel/proc.c b/arch/mips/kernel/proc.c
index 6e6e947..34dd228 100644
--- a/arch/mips/kernel/proc.c
+++ b/arch/mips/kernel/proc.c
@@ -62,6 +62,7 @@
);
seq_printf(m, "shadow register sets\t: %d\n",
cpu_data[n].srsets);
+ seq_printf(m, "core\t\t\t: %d\n", cpu_data[n].core);
sprintf(fmt, "VCE%%c exceptions\t\t: %s\n",
cpu_has_vce ? "%u" : "not available");
diff --git a/arch/mips/kernel/smp-mt.c b/arch/mips/kernel/smp-mt.c
index 94e210c..2ab0b7e 100644
--- a/arch/mips/kernel/smp-mt.c
+++ b/arch/mips/kernel/smp-mt.c
@@ -22,6 +22,7 @@
#include <linux/cpumask.h>
#include <linux/interrupt.h>
#include <linux/compiler.h>
+#include <linux/smp.h>
#include <asm/atomic.h>
#include <asm/cacheflush.h>
@@ -30,7 +31,6 @@
#include <asm/system.h>
#include <asm/hardirq.h>
#include <asm/mmu_context.h>
-#include <asm/smp.h>
#include <asm/time.h>
#include <asm/mipsregs.h>
#include <asm/mipsmtregs.h>
@@ -223,6 +223,7 @@
void __init plat_smp_setup(void)
{
unsigned int mvpconf0, ntc, tc, ncpu = 0;
+ unsigned int nvpe;
#ifdef CONFIG_MIPS_MT_FPAFF
/* If we have an FPU, enroll ourselves in the FPU-full mask */
@@ -242,6 +243,9 @@
mvpconf0 = read_c0_mvpconf0();
ntc = (mvpconf0 & MVPCONF0_PTC) >> MVPCONF0_PTC_SHIFT;
+ nvpe = ((mvpconf0 & MVPCONF0_PVPE) >> MVPCONF0_PVPE_SHIFT) + 1;
+ smp_num_siblings = nvpe;
+
/* we'll always have more TC's than VPE's, so loop setting everything
to a sensible state */
for (tc = 0; tc <= ntc; tc++) {
diff --git a/arch/mips/kernel/smp.c b/arch/mips/kernel/smp.c
index 63989e9..335be9b 100644
--- a/arch/mips/kernel/smp.c
+++ b/arch/mips/kernel/smp.c
@@ -56,6 +56,34 @@
extern void __init calibrate_delay(void);
extern void cpu_idle(void);
+/* Number of TCs (or siblings in Intel speak) per CPU core */
+int smp_num_siblings = 1;
+EXPORT_SYMBOL(smp_num_siblings);
+
+/* representing the TCs (or siblings in Intel speak) of each logical CPU */
+cpumask_t cpu_sibling_map[NR_CPUS] __read_mostly;
+EXPORT_SYMBOL(cpu_sibling_map);
+
+/* representing cpus for which sibling maps can be computed */
+static cpumask_t cpu_sibling_setup_map;
+
+static inline void set_cpu_sibling_map(int cpu)
+{
+ int i;
+
+ cpu_set(cpu, cpu_sibling_setup_map);
+
+ if (smp_num_siblings > 1) {
+ for_each_cpu_mask(i, cpu_sibling_setup_map) {
+ if (cpu_data[cpu].core == cpu_data[i].core) {
+ cpu_set(i, cpu_sibling_map[cpu]);
+ cpu_set(cpu, cpu_sibling_map[i]);
+ }
+ }
+ } else
+ cpu_set(cpu, cpu_sibling_map[cpu]);
+}
+
/*
* First C code run on the secondary CPUs after being started up by
* the master.
@@ -85,6 +113,7 @@
cpu_data[cpu].udelay_val = loops_per_jiffy;
prom_smp_finish();
+ set_cpu_sibling_map(cpu);
cpu_set(cpu, cpu_callin_map);
@@ -258,6 +287,7 @@
init_new_context(current, &init_mm);
current_thread_info()->cpu = 0;
plat_prepare_cpus(max_cpus);
+ set_cpu_sibling_map(0);
#ifndef CONFIG_HOTPLUG_CPU
cpu_present_map = cpu_possible_map;
#endif
diff --git a/include/asm-mips/cpu-info.h b/include/asm-mips/cpu-info.h
index ed5c02c..0c5a358 100644
--- a/include/asm-mips/cpu-info.h
+++ b/include/asm-mips/cpu-info.h
@@ -55,6 +55,7 @@
struct cache_desc scache; /* Secondary cache */
struct cache_desc tcache; /* Tertiary/split secondary cache */
int srsets; /* Shadow register sets */
+ int core; /* physical core number */
#if defined(CONFIG_MIPS_MT_SMTC)
/*
* In the MIPS MT "SMTC" model, each TC is considered
@@ -63,8 +64,10 @@
* to all TCs within the same VPE.
*/
int vpe_id; /* Virtual Processor number */
- int tc_id; /* Thread Context number */
#endif /* CONFIG_MIPS_MT */
+#ifdef CONFIG_MIPS_MT_SMTC
+ int tc_id; /* Thread Context number */
+#endif
void *data; /* Additional data */
} __attribute__((aligned(SMP_CACHE_BYTES)));
diff --git a/include/asm-mips/smp.h b/include/asm-mips/smp.h
index dc770025..2326587 100644
--- a/include/asm-mips/smp.h
+++ b/include/asm-mips/smp.h
@@ -20,6 +20,9 @@
#include <linux/cpumask.h>
#include <asm/atomic.h>
+extern int smp_num_siblings;
+extern cpumask_t cpu_sibling_map[];
+
#define raw_smp_processor_id() (current_thread_info()->cpu)
/* Map from cpu id to sequential logical cpu number. This will only
diff --git a/include/asm-mips/topology.h b/include/asm-mips/topology.h
index 0440fb9..259145e 100644
--- a/include/asm-mips/topology.h
+++ b/include/asm-mips/topology.h
@@ -1 +1,17 @@
+/*
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License. See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * Copyright (C) 2007 by Ralf Baechle
+ */
+#ifndef __ASM_TOPOLOGY_H
+#define __ASM_TOPOLOGY_H
+
#include <topology.h>
+
+#ifdef CONFIG_SMP
+#define smt_capable() (smp_num_siblings > 1)
+#endif
+
+#endif /* __ASM_TOPOLOGY_H */