On Fri, Sep 30, 2016 at 12:49:52PM +0800, Pan Xinhui wrote: > > > 在 2016/9/29 23:51, Christian Borntraeger 写道: > > this implements the s390 backend for commit > > "kernel/sched: introduce vcpu preempted check interface" > > by reworking the existing smp_vcpu_scheduled into > > arch_vcpu_is_preempted. We can then also get rid of the > > local cpu_is_preempted function by moving the > > CIF_ENABLED_WAIT test into arch_vcpu_is_preempted. > > > > Signed-off-by: Christian Borntraeger <[email protected]> > > --- > > hi, Christian > thanks for your patch! > > > arch/s390/include/asm/spinlock.h | 3 +++ > > arch/s390/kernel/smp.c | 9 +++++++-- > > arch/s390/lib/spinlock.c | 25 ++++++++----------------- > > 3 files changed, 18 insertions(+), 19 deletions(-) > > > > diff --git a/arch/s390/include/asm/spinlock.h > > b/arch/s390/include/asm/spinlock.h > > index 63ebf37..e16e02f 100644 > > --- a/arch/s390/include/asm/spinlock.h > > +++ b/arch/s390/include/asm/spinlock.h > > @@ -21,6 +21,9 @@ _raw_compare_and_swap(unsigned int *lock, unsigned int > > old, unsigned int new) > > return __sync_bool_compare_and_swap(lock, old, new); > > } > > > > +bool arch_vcpu_is_preempted(int cpu); > > +#define vcpu_is_preempted arch_vcpu_is_preempted > > + > > /* > > * Simple spin lock operations. There are two variants, one clears IRQ's > > * on the local processor, one does not. > > diff --git a/arch/s390/kernel/smp.c b/arch/s390/kernel/smp.c > > index 7b89a75..4aadd16 100644 > > --- a/arch/s390/kernel/smp.c > > +++ b/arch/s390/kernel/smp.c > > @@ -376,10 +376,15 @@ int smp_find_processor_id(u16 address) > > return -1; > > } > > > > -int smp_vcpu_scheduled(int cpu) > root@ltcalpine2-lp13:~/linux# git grep -wn smp_vcpu_scheduled arch/s390/ > arch/s390/include/asm/smp.h:34:extern int smp_vcpu_scheduled(int cpu); > arch/s390/include/asm/smp.h:56:static inline int smp_vcpu_scheduled(int cpu) > { return 1; } > arch/s390/kernel/smp.c:371:int smp_vcpu_scheduled(int cpu) > arch/s390/lib/spinlock.c:44: if (smp_vcpu_scheduled(cpu)) > > > +bool arch_vcpu_is_preempted(int cpu) > > { > > - return pcpu_running(pcpu_devices + cpu); > > + if (test_cpu_flag_of(CIF_ENABLED_WAIT, cpu)) > > + return false; > > + if (pcpu_running(pcpu_devices + cpu)) > > + return false; > I saw smp_vcpu_scheduled() returns true always on !SMP system. > > maybe we can do somegthing silimar. like below > > #ifndef CONFIG_SMP > static inline bool arch_vcpu_is_preempted(int cpu) { return > !test_cpu_flag_of(CIF_ENABLED_WAIT, cpu); } > #else > ... > > but I can't help thinking that if this is a!SMP system, maybe we could only > #ifndef CONFIG_SMP > static inline bool arch_vcpu_is_preempted(int cpu) { return false; } > #else
Why do we need a vcpu_is_preempted() implementation for UP? Where will
you use it?
Regards,
Boqun
> ...
>
>
> thanks
> xinhui
>
> > + return true;
> > }
> > +EXPORT_SYMBOL(arch_vcpu_is_preempted);
> >
> > void smp_yield_cpu(int cpu)
> > {
> > diff --git a/arch/s390/lib/spinlock.c b/arch/s390/lib/spinlock.c
> > index e5f50a7..e48a48e 100644
> > --- a/arch/s390/lib/spinlock.c
> > +++ b/arch/s390/lib/spinlock.c
> > @@ -37,15 +37,6 @@ static inline void _raw_compare_and_delay(unsigned int
> > *lock, unsigned int old)
> > asm(".insn rsy,0xeb0000000022,%0,0,%1" : : "d" (old), "Q" (*lock));
> > }
> >
> > -static inline int cpu_is_preempted(int cpu)
> > -{
> > - if (test_cpu_flag_of(CIF_ENABLED_WAIT, cpu))
> > - return 0;
> > - if (smp_vcpu_scheduled(cpu))
> > - return 0;
> > - return 1;
> > -}
> > -
> > void arch_spin_lock_wait(arch_spinlock_t *lp)
> > {
> > unsigned int cpu = SPINLOCK_LOCKVAL;
> > @@ -62,7 +53,7 @@ void arch_spin_lock_wait(arch_spinlock_t *lp)
> > continue;
> > }
> > /* First iteration: check if the lock owner is running. */
> > - if (first_diag && cpu_is_preempted(~owner)) {
> > + if (first_diag && arch_vcpu_is_preempted(~owner)) {
> > smp_yield_cpu(~owner);
> > first_diag = 0;
> > continue;
> > @@ -81,7 +72,7 @@ void arch_spin_lock_wait(arch_spinlock_t *lp)
> > * yield the CPU unconditionally. For LPAR rely on the
> > * sense running status.
> > */
> > - if (!MACHINE_IS_LPAR || cpu_is_preempted(~owner)) {
> > + if (!MACHINE_IS_LPAR || arch_vcpu_is_preempted(~owner)) {
> > smp_yield_cpu(~owner);
> > first_diag = 0;
> > }
> > @@ -108,7 +99,7 @@ void arch_spin_lock_wait_flags(arch_spinlock_t *lp,
> > unsigned long flags)
> > continue;
> > }
> > /* Check if the lock owner is running. */
> > - if (first_diag && cpu_is_preempted(~owner)) {
> > + if (first_diag && arch_vcpu_is_preempted(~owner)) {
> > smp_yield_cpu(~owner);
> > first_diag = 0;
> > continue;
> > @@ -127,7 +118,7 @@ void arch_spin_lock_wait_flags(arch_spinlock_t *lp,
> > unsigned long flags)
> > * yield the CPU unconditionally. For LPAR rely on the
> > * sense running status.
> > */
> > - if (!MACHINE_IS_LPAR || cpu_is_preempted(~owner)) {
> > + if (!MACHINE_IS_LPAR || arch_vcpu_is_preempted(~owner)) {
> > smp_yield_cpu(~owner);
> > first_diag = 0;
> > }
> > @@ -165,7 +156,7 @@ void _raw_read_lock_wait(arch_rwlock_t *rw)
> > owner = 0;
> > while (1) {
> > if (count-- <= 0) {
> > - if (owner && cpu_is_preempted(~owner))
> > + if (owner && arch_vcpu_is_preempted(~owner))
> > smp_yield_cpu(~owner);
> > count = spin_retry;
> > }
> > @@ -211,7 +202,7 @@ void _raw_write_lock_wait(arch_rwlock_t *rw, unsigned
> > int prev)
> > owner = 0;
> > while (1) {
> > if (count-- <= 0) {
> > - if (owner && cpu_is_preempted(~owner))
> > + if (owner && arch_vcpu_is_preempted(~owner))
> > smp_yield_cpu(~owner);
> > count = spin_retry;
> > }
> > @@ -241,7 +232,7 @@ void _raw_write_lock_wait(arch_rwlock_t *rw)
> > owner = 0;
> > while (1) {
> > if (count-- <= 0) {
> > - if (owner && cpu_is_preempted(~owner))
> > + if (owner && arch_vcpu_is_preempted(~owner))
> > smp_yield_cpu(~owner);
> > count = spin_retry;
> > }
> > @@ -285,7 +276,7 @@ void arch_lock_relax(unsigned int cpu)
> > {
> > if (!cpu)
> > return;
> > - if (MACHINE_IS_LPAR && !cpu_is_preempted(~cpu))
> > + if (MACHINE_IS_LPAR && !arch_vcpu_is_preempted(~cpu))
> > return;
> > smp_yield_cpu(~cpu);
> > }
> >
>
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