Commit c71085f2 authored by Gregory CLEMENT's avatar Gregory CLEMENT Committed by Thomas Bogendoerfer
Browse files

MIPS: CPS: Improve mips_cps_first_online_in_cluster() 



The initial implementation of this function goes through all the CPUs
in a cluster to determine if the current CPU is the only one
running. This process occurs every time the function is called.

However, during boot, we already perform this task, so let's take
advantage of this opportunity to create and fill a CPU bitmask that
can be easily and efficiently used later.

This patch modifies the function to allow providing the first
available online CPU when one already exists, which is necessary for
delay CPU calibration optimization.

Reviewed-by: default avatarJiaxun Yang <jiaxun.yang@flygoat.com>
Signed-off-by: default avatarGregory CLEMENT <gregory.clement@bootlin.com>
Signed-off-by: default avatarThomas Bogendoerfer <tsbogend@alpha.franken.de>
parent 07f8888e

arch/mips/include/asm/mips-cps.h

+3 −1
Original line number Diff line number Diff line
@@ -258,6 +258,8 @@ static inline bool mips_cps_multicluster_cpus(void) 


/**

 * mips_cps_first_online_in_cluster() - Detect if CPU is first online in cluster

 * @first_cpu: The first other online CPU in cluster, or nr_cpu_ids if

 * the function returns true.

 *

 * Determine whether the local CPU is the first to be brought online in its

 * cluster - that is, whether there are any other online CPUs in the local
@@ -265,6 +267,6 @@ static inline bool mips_cps_multicluster_cpus(void) 
 *

 * Returns true if this CPU is first online, else false.

 */

extern unsigned int mips_cps_first_online_in_cluster(void);

extern unsigned int mips_cps_first_online_in_cluster(int *first_cpu);



#endif /* __MIPS_ASM_MIPS_CPS_H__ */

arch/mips/include/asm/smp-cps.h

+1 −0
Original line number Diff line number Diff line
@@ -24,6 +24,7 @@ struct core_boot_config { 


struct cluster_boot_config {

	unsigned long *core_power;

	struct cpumask cpumask;

	struct core_boot_config *core_config;

};

arch/mips/kernel/mips-cm.c

+16 −31
Original line number Diff line number Diff line
@@ -10,6 +10,7 @@ 
#include <linux/spinlock.h>



#include <asm/mips-cps.h>

#include <asm/smp-cps.h>

#include <asm/mipsregs.h>



void __iomem *mips_gcr_base;
@@ -534,39 +535,23 @@ void mips_cm_error_report(void) 
	write_gcr_error_cause(cm_error);

}



unsigned int mips_cps_first_online_in_cluster(void)

unsigned int mips_cps_first_online_in_cluster(int *first_cpu)

{

	unsigned int local_cl;

	int i;



	local_cl = cpu_cluster(&current_cpu_data);

	unsigned int local_cl = cpu_cluster(&current_cpu_data);

	struct cpumask *local_cl_mask;



	/*

	 * We rely upon knowledge that CPUs are numbered sequentially by

	 * cluster - ie. CPUs 0..X will be in cluster 0, CPUs X+1..Y in cluster

	 * 1, CPUs Y+1..Z in cluster 2 etc. This means that CPUs in the same

	 * cluster will immediately precede or follow one another.

	 *

	 * First we scan backwards, until we find an online CPU in the cluster

	 * or we move on to another cluster.

	 * mips_cps_cluster_bootcfg is allocated in cps_prepare_cpus. If it is

	 * not yet done, then we are so early that only one CPU is running, so

	 * it is the first online CPU in the cluster.

	 */

	for (i = smp_processor_id() - 1; i >= 0; i--) {

		if (cpu_cluster(&cpu_data[i]) != local_cl)

			break;

		if (!cpu_online(i))

			continue;

		return false;

	}



	/* Then do the same for higher numbered CPUs */

	for (i = smp_processor_id() + 1; i < nr_cpu_ids; i++) {

		if (cpu_cluster(&cpu_data[i]) != local_cl)

			break;

		if (!cpu_online(i))

			continue;

		return false;

	}



	/* We found no online CPUs in the local cluster */

	if  (IS_ENABLED(CONFIG_MIPS_CPS) && mips_cps_cluster_bootcfg)

		local_cl_mask = &mips_cps_cluster_bootcfg[local_cl].cpumask;

	else

		return true;



	*first_cpu = cpumask_any_and_but(local_cl_mask,

					 cpu_online_mask,

					 smp_processor_id());

	return (*first_cpu >= nr_cpu_ids);

}

arch/mips/kernel/smp-cps.c

+4 −1
Original line number Diff line number Diff line
@@ -283,7 +283,7 @@ static void __init cps_smp_setup(void) 


static void __init cps_prepare_cpus(unsigned int max_cpus)

{

	unsigned int nclusters, ncores, core_vpes, c, cl, cca;

	unsigned int nclusters, ncores, core_vpes, nvpe = 0, c, cl, cca;

	bool cca_unsuitable, cores_limited;

	struct cluster_boot_config *cluster_bootcfg;

	struct core_boot_config *core_bootcfg;
@@ -356,10 +356,13 @@ static void __init cps_prepare_cpus(unsigned int max_cpus) 


		/* Allocate VPE boot configuration structs */

		for (c = 0; c < ncores; c++) {

			int v;

			core_vpes = core_vpe_count(cl, c);

			core_bootcfg[c].vpe_config = kcalloc(core_vpes,

					sizeof(*core_bootcfg[c].vpe_config),

					GFP_KERNEL);

			for (v = 0; v < core_vpes; v++)

				cpumask_set_cpu(nvpe++, &mips_cps_cluster_bootcfg[cl].cpumask);

			if (!core_bootcfg[c].vpe_config)

				goto err_out;

		}