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Commit 70b8301f authored by Andi Kleen's avatar Andi Kleen Committed by Ingo Molnar
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x86/topology: Add topology_max_smt_threads() 



For SMT specific workarounds it is useful to know if SMT is active
on any online CPU in the system. This currently requires a loop
over all online CPUs.

Add a global variable that is updated with the maximum number
of smt threads on any CPU on online/offline, and use it for
topology_max_smt_threads()

The single call is easier to use than a loop.

Not exported to user space because user space already can use
the existing sibling interfaces to find this out.

Signed-off-by: default avatarAndi Kleen <ak@linux.intel.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Cc: acme@kernel.org
Cc: jolsa@kernel.org
Link: http://lkml.kernel.org/r/1463703002-19686-2-git-send-email-andi@firstfloor.org


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent dc89e75a

arch/x86/include/asm/topology.h

+9 −0
Original line number Diff line number Diff line
@@ -129,6 +129,14 @@ extern const struct cpumask *cpu_coregroup_mask(int cpu); 


extern unsigned int __max_logical_packages;

#define topology_max_packages()			(__max_logical_packages)



extern int __max_smt_threads;



static inline int topology_max_smt_threads(void)

{

	return __max_smt_threads;

}



int topology_update_package_map(unsigned int apicid, unsigned int cpu);

extern int topology_phys_to_logical_pkg(unsigned int pkg);

#else
@@ -136,6 +144,7 @@ extern int topology_phys_to_logical_pkg(unsigned int pkg); 
static inline int

topology_update_package_map(unsigned int apicid, unsigned int cpu) { return 0; }

static inline int topology_phys_to_logical_pkg(unsigned int pkg) { return 0; }

static inline int topology_max_smt_threads(void) { return 1; }

#endif



static inline void arch_fix_phys_package_id(int num, u32 slot)

arch/x86/kernel/smpboot.c

+24 −1
Original line number Diff line number Diff line
@@ -105,6 +105,9 @@ static unsigned int max_physical_pkg_id __read_mostly; 
unsigned int __max_logical_packages __read_mostly;

EXPORT_SYMBOL(__max_logical_packages);



/* Maximum number of SMT threads on any online core */

int __max_smt_threads __read_mostly;



static inline void smpboot_setup_warm_reset_vector(unsigned long start_eip)

{

	unsigned long flags;
@@ -493,7 +496,7 @@ void set_cpu_sibling_map(int cpu) 
	bool has_mp = has_smt || boot_cpu_data.x86_max_cores > 1;

	struct cpuinfo_x86 *c = &cpu_data(cpu);

	struct cpuinfo_x86 *o;

	int i;

	int i, threads;



	cpumask_set_cpu(cpu, cpu_sibling_setup_mask);
@@ -550,6 +553,10 @@ void set_cpu_sibling_map(int cpu) 
		if (match_die(c, o) && !topology_same_node(c, o))

			primarily_use_numa_for_topology();

	}



	threads = cpumask_weight(topology_sibling_cpumask(cpu));

	if (threads > __max_smt_threads)

		__max_smt_threads = threads;

}



/* maps the cpu to the sched domain representing multi-core */
@@ -1441,6 +1448,21 @@ __init void prefill_possible_map(void) 


#ifdef CONFIG_HOTPLUG_CPU



/* Recompute SMT state for all CPUs on offline */

static void recompute_smt_state(void)

{

	int max_threads, cpu;



	max_threads = 0;

	for_each_online_cpu (cpu) {

		int threads = cpumask_weight(topology_sibling_cpumask(cpu));



		if (threads > max_threads)

			max_threads = threads;

	}

	__max_smt_threads = max_threads;

}



static void remove_siblinginfo(int cpu)

{

	int sibling;
@@ -1465,6 +1487,7 @@ static void remove_siblinginfo(int cpu) 
	c->phys_proc_id = 0;

	c->cpu_core_id = 0;

	cpumask_clear_cpu(cpu, cpu_sibling_setup_mask);

	recompute_smt_state();

}



static void remove_cpu_from_maps(int cpu)