From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935559AbcI3EuR (ORCPT ); Fri, 30 Sep 2016 00:50:17 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:33238 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S932905AbcI3EuI (ORCPT ); Fri, 30 Sep 2016 00:50:08 -0400 Subject: Re: [PATCH v2 1/1] s390/spinlock: Provide vcpu_is_preempted To: Christian Borntraeger , Peter Zijlstra , Martin Schwidefsky , Heiko Carstens References: <1475164265-246160-1-git-send-email-borntraeger@de.ibm.com> <1475164265-246160-2-git-send-email-borntraeger@de.ibm.com> Cc: Pan Xinhui , linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, linux-s390@vger.kernel.org, kvm@vger.kernel.org, xen-devel-request@lists.xenproject.org, benh@kernel.crashing.org, paulus@samba.org, mpe@ellerman.id.au, mingo@redhat.com, paulmck@linux.vnet.ibm.com, will.deacon@arm.com, kernellwp@gmail.com, jgross@suse.com, pbonzini@redhat.com, bsingharora@gmail.com From: Pan Xinhui Date: Fri, 30 Sep 2016 12:49:52 +0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.12; rv:45.0) Gecko/20100101 Thunderbird/45.2.0 MIME-Version: 1.0 In-Reply-To: <1475164265-246160-2-git-send-email-borntraeger@de.ibm.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Content-Scanned: Fidelis XPS MAILER x-cbid: 16093004-0004-0000-0000-000010810520 X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00005828; HX=3.00000240; KW=3.00000007; PH=3.00000004; SC=3.00000186; SDB=6.00762954; UDB=6.00363735; IPR=6.00538075; BA=6.00004771; NDR=6.00000001; ZLA=6.00000005; ZF=6.00000009; ZB=6.00000000; ZP=6.00000000; ZH=6.00000000; ZU=6.00000002; MB=3.00012827; XFM=3.00000011; UTC=2016-09-30 04:50:06 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 16093004-0005-0000-0000-000079569471 Message-Id: X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2016-09-30_01:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=0 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1609280000 definitions=main-1609300087 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 > --- 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 ... 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); > } >