lk/linux-kernel-test
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

[S390] spinlock: check virtual cpu running status

Browse Source 
This patch introduces a new function that checks the running status
of a cpu in a hypervisor. This status is not virtualized, so the check
is only correct if running in an LPAR. On acquiring a spinlock, if the
cpu holding the lock is scheduled by the hypervisor, we do a busy wait
on the lock. If it is not scheduled, we yield over to that cpu.

Signed-off-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Gerald Schaefer
2010-02-26 22:37:40 +01:00
committed by Martin Schwidefsky
parent 8387c736fc
commit 59b6978745
3 changed files with 80 additions and 37 deletions
Download Patch File Download Diff File Expand all files Collapse all files

24
arch/s390/include/asm/smp.h
View File

@@ -36,6 +36,28 @@ extern void smp_switch_to_cpu(void (*)(void *), void *, unsigned long sp,
int from, int to);
extern void smp_restart_cpu(void);
/*
* returns 1 if (virtual) cpu is scheduled
* returns 0 otherwise
*/
static inline int smp_vcpu_scheduled(int cpu)
{
u32 status;
switch (sigp_ps(&status, 0, cpu, sigp_sense_running)) {
case sigp_status_stored:
/* Check for running status */
if (status & 0x400)
return 0;
break;
case sigp_not_operational:
return 0;
default:
break;
}
return 1;
}
#else /* CONFIG_SMP */
static inline void smp_switch_to_ipl_cpu(void (*func)(void *), void *data)
@@ -43,6 +65,8 @@ static inline void smp_switch_to_ipl_cpu(void (*func)(void *), void *data)
func(data);
}
#define smp_vcpu_scheduled (1)
#endif /* CONFIG_SMP */
#ifdef CONFIG_HOTPLUG_CPU