Commit 5389e239 authored by David S. Miller's avatar David S. Miller
Browse files

Merge branch 'sparc64-Use-low-latency-path-to-resume-idle-cpu' 



Vijay Kumar says:

====================
sparc64: Use low latency path to resume idle cpu

CPU_POKE is a low latency path to resume the target cpu if suspended
using CPU_YIELD. Use CPU_POKE to resume cpu if supported by hypervisor.

	     Hackbench results (lower is better):
Number of
Process:		w/o fix		with fix
1  			0.012		 0.010
10			0.021		 0.019
100			0.151		 0.148

Changelog:
v2:
  - Fixed comments and spacing (2/2)
====================

Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parents 99274b81 8536e02e

arch/sparc/include/asm/hypervisor.h

+18 −0
Original line number Diff line number Diff line
@@ -298,6 +298,24 @@ unsigned long sun4v_cpu_stop(unsigned long cpuid); 
unsigned long sun4v_cpu_yield(void);

#endif



/* cpu_poke()

 * TRAP:	HV_FAST_TRAP

 * FUNCTION:	HV_FAST_CPU_POKE

 * RET0:	status

 * ERRORS:	ENOCPU		cpuid refers to a CPU that does not exist

 *		EINVAL		cpuid is current CPU

 *

 * Poke CPU cpuid. If the target CPU is currently suspended having

 * invoked the cpu-yield service, that vCPU will be resumed.

 * Poke interrupts may only be sent to valid, non-local CPUs.

 * It is not legal to poke the current vCPU.

 */

#define HV_FAST_CPU_POKE                0x13



#ifndef __ASSEMBLY__

unsigned long sun4v_cpu_poke(unsigned long cpuid);

#endif



/* cpu_qconf()

 * TRAP:	HV_FAST_TRAP

 * FUNCTION:	HV_FAST_CPU_QCONF

arch/sparc/include/asm/smp_64.h

+5 −0
Original line number Diff line number Diff line
@@ -33,6 +33,9 @@ 
DECLARE_PER_CPU(cpumask_t, cpu_sibling_map);

extern cpumask_t cpu_core_map[NR_CPUS];



void smp_init_cpu_poke(void);

void scheduler_poke(void);



void arch_send_call_function_single_ipi(int cpu);

void arch_send_call_function_ipi_mask(const struct cpumask *mask);
@@ -74,6 +77,8 @@ void __cpu_die(unsigned int cpu); 
#define smp_fetch_global_regs() do { } while (0)

#define smp_fetch_global_pmu() do { } while (0)

#define smp_fill_in_cpu_possible_map() do { } while (0)

#define smp_init_cpu_poke() do { } while (0)

#define scheduler_poke() do { } while (0)



#endif /* !(CONFIG_SMP) */

arch/sparc/kernel/hvapi.c

+1 −1
Original line number Diff line number Diff line
@@ -189,7 +189,7 @@ void __init sun4v_hvapi_init(void) 


	group = HV_GRP_CORE;

	major = 1;

	minor = 1;

	minor = 6;

	if (sun4v_hvapi_register(group, major, &minor))

		goto bad;

arch/sparc/kernel/hvcalls.S

+11 −0
Original line number Diff line number Diff line
@@ -106,6 +106,17 @@ ENTRY(sun4v_cpu_yield) 
	 nop

ENDPROC(sun4v_cpu_yield)



	/* %o0: cpuid

	 *

	 * returns %o0:	status

	 */

ENTRY(sun4v_cpu_poke)

	mov     HV_FAST_CPU_POKE, %o5

	ta      HV_FAST_TRAP

	retl

	 nop

ENDPROC(sun4v_cpu_poke)



	/* %o0:	type

	 * %o1:	queue paddr

	 * %o2:	num queue entries

arch/sparc/kernel/process_64.c

+6 −1
Original line number Diff line number Diff line
@@ -77,8 +77,13 @@ void arch_cpu_idle(void) 
			: "=&r" (pstate)

			: "i" (PSTATE_IE));



		if (!need_resched() && !cpu_is_offline(smp_processor_id()))

		if (!need_resched() && !cpu_is_offline(smp_processor_id())) {

			sun4v_cpu_yield();

			/* If resumed by cpu_poke then we need to explicitly

			 * call scheduler_ipi().

			 */

			scheduler_poke();

		}



		/* Re-enable interrupts. */

		__asm__ __volatile__(

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