[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 11bc17ce0ebf5e1efcae5ee34fc24159fe837ccd..d5a89f3fdfd3ec33c309f6d5bdeac919499ded03 100644 (file)
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -1442,6 +1442,7 @@ config MIPS_MT_SMP
        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 @@ endchoice
 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 6e6e947cce1efe6fac56d54f1a795a6ac9ad7b03..34dd22838fdb57677271053ebfa905b5ffa7b40f 100644 (file)
--- a/arch/mips/kernel/proc.c
+++ b/arch/mips/kernel/proc.c
@@ -62,6 +62,7 @@ static int show_cpuinfo(struct seq_file *m, void *v)
                );
        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 94e210cc6cb6725675389ba84d190c97d63be789..2ab0b7eeaa7e81060c6067423b94b3586cdc2153 100644 (file)
--- 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 @@ static void __init smp_tc_init(unsigned int tc, unsigned int mvpconf0)
 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 @@ void __init plat_smp_setup(void)
        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 63989e9df4f97099b73889d3610b6111d2447b0c..335be9bcf0dc8b11effd1c78689294ed946af2a9 100644 (file)
--- a/arch/mips/kernel/smp.c
+++ b/arch/mips/kernel/smp.c
@@ -56,6 +56,34 @@ EXPORT_SYMBOL(cpu_online_map);
 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 @@ asmlinkage __cpuinit void start_secondary(void)
        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 @@ void __init smp_prepare_cpus(unsigned int max_cpus)
        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 ed5c02c6afbbafa98420565c8f7a88c74bbe2e27..0c5a358863f36067eb8fdbcdbd40166ccfec4954 100644 (file)
--- a/include/asm-mips/cpu-info.h
+++ b/include/asm-mips/cpu-info.h
@@ -55,6 +55,7 @@ struct cpuinfo_mips {
        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 @@ struct cpuinfo_mips {
         * 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 dc770025a9b0c98fcbe954f677713c0f85f91b7d..23265879cee90509672897553656ca4476da684a 100644 (file)
--- 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 0440fb9f218044d504cdf18ee13ca8d836fbdd63..259145e07e9724a2e1bcd22e3ed9ee52a8f9580c 100644 (file)
--- 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 */