| Message ID | f521d8cb-c38b-a608-eca8-a5c45184bbca@de.ibm.com (mailing list archive) |
|---|---|
| State | Not Applicable |
| Headers | show |
On 09/29/2016 12:40 PM, Christian Borntraeger wrote: > On 09/29/2016 12:23 PM, Christian Borntraeger wrote: >> On 09/29/2016 12:10 PM, Peter Zijlstra wrote: >>> On Thu, Jul 21, 2016 at 07:45:10AM -0400, Pan Xinhui wrote: >>>> change from v2: >>>> no code change, fix typos, update some comments >>>> >>>> change from v1: >>>> a simplier definition of default vcpu_is_preempted >>>> skip mahcine type check on ppc, and add config. remove dedicated macro. >>>> add one patch to drop overload of rwsem_spin_on_owner and mutex_spin_on_owner. >>>> add more comments >>>> thanks boqun and Peter's suggestion. >>>> >>>> This patch set aims to fix lock holder preemption issues. >>> >>> So I really like the concept, but I would also really like to see >>> support for more hypervisors included before we can move forward with >>> this. >>> >>> Please consider s390 and (x86/arm) KVM. Once we have a few, more can >>> follow later, but I think its important to not only have PPC support for >>> this. >> >> Actually the s390 preemted check via sigp sense running is available for >> all hypervisors (z/VM, LPAR and KVM) which implies everywhere as you can no >> longer buy s390 systems without LPAR. >> >> As Heiko already pointed out we could simply use a small inline function >> that calls cpu_is_preempted from arch/s390/lib/spinlock (or smp_vcpu_scheduled from smp.c) > > Maybe something like > (untested and just pasted, so white space damaged) Now tested. With 8 host cpus and 16 guest cpus perf bench sched shows the same improvements as in Pan Xinhuis cover letter. Also the runtime shrinks a lot. > > diff --git a/arch/s390/include/asm/spinlock.h b/arch/s390/include/asm/spinlock.h > index 63ebf37..6e82986 100644 > --- a/arch/s390/include/asm/spinlock.h > +++ b/arch/s390/include/asm/spinlock.h > @@ -21,6 +21,13 @@ _raw_compare_and_swap(unsigned int *lock, unsigned int old, unsigned int new) > return __sync_bool_compare_and_swap(lock, old, new); > } > > +int arch_vcpu_is_preempted(int cpu); > +#define vcpu_is_preempted cpu_is_preempted > +static inline bool cpu_is_preempted(int cpu) > +{ > + return arch_vcpu_is_preempted(cpu); > +} > + > /* > * Simple spin lock operations. There are two variants, one clears IRQ's > * on the local processor, one does not. > diff --git a/arch/s390/lib/spinlock.c b/arch/s390/lib/spinlock.c > index e5f50a7..260d179 100644 > --- a/arch/s390/lib/spinlock.c > +++ b/arch/s390/lib/spinlock.c > @@ -37,7 +37,7 @@ 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) > +int arch_vcpu_is_preempted(int cpu) > { > if (test_cpu_flag_of(CIF_ENABLED_WAIT, cpu)) > return 0; > @@ -45,6 +45,7 @@ static inline int cpu_is_preempted(int cpu) > return 0; > return 1; > } > +EXPORT_SYMBOL(arch_vcpu_is_preempted); > > void arch_spin_lock_wait(arch_spinlock_t *lp) > { > > > > If ok I can respin into a proper patch.
diff --git a/arch/s390/include/asm/spinlock.h b/arch/s390/include/asm/spinlock.h index 63ebf37..6e82986 100644 --- a/arch/s390/include/asm/spinlock.h +++ b/arch/s390/include/asm/spinlock.h @@ -21,6 +21,13 @@ _raw_compare_and_swap(unsigned int *lock, unsigned int old, unsigned int new) return __sync_bool_compare_and_swap(lock, old, new); } +int arch_vcpu_is_preempted(int cpu); +#define vcpu_is_preempted cpu_is_preempted +static inline bool cpu_is_preempted(int cpu) +{ + return arch_vcpu_is_preempted(cpu); +} + /* * Simple spin lock operations. There are two variants, one clears IRQ's * on the local processor, one does not. diff --git a/arch/s390/lib/spinlock.c b/arch/s390/lib/spinlock.c index e5f50a7..260d179 100644 --- a/arch/s390/lib/spinlock.c +++ b/arch/s390/lib/spinlock.c @@ -37,7 +37,7 @@ 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) +int arch_vcpu_is_preempted(int cpu) { if (test_cpu_flag_of(CIF_ENABLED_WAIT, cpu)) return 0; @@ -45,6 +45,7 @@ static inline int cpu_is_preempted(int cpu) return 0; return 1; } +EXPORT_SYMBOL(arch_vcpu_is_preempted); void arch_spin_lock_wait(arch_spinlock_t *lp) {