Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753109AbcKBFNg (ORCPT ); Wed, 2 Nov 2016 01:13:36 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:33218 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752916AbcKBFNe (ORCPT ); Wed, 2 Nov 2016 01:13:34 -0400 From: Pan Xinhui To: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, virtualization@lists.linux-foundation.org, linux-s390@vger.kernel.org, xen-devel-request@lists.xenproject.org, kvm@vger.kernel.org, xen-devel@lists.xenproject.org, x86@kernel.org Cc: benh@kernel.crashing.org, paulus@samba.org, mpe@ellerman.id.au, mingo@redhat.com, peterz@infradead.org, paulmck@linux.vnet.ibm.com, will.deacon@arm.com, kernellwp@gmail.com, jgross@suse.com, pbonzini@redhat.com, bsingharora@gmail.com, boqun.feng@gmail.com, borntraeger@de.ibm.com, rkrcmar@redhat.com, David.Laight@ACULAB.COM, dave@stgolabs.net, konrad.wilk@oracle.com, Pan Xinhui Subject: [PATCH v7 01/11] kernel/sched: introduce vcpu preempted check interface Date: Wed, 2 Nov 2016 05:08:28 -0400 X-Mailer: git-send-email 2.4.11 In-Reply-To: <1478077718-37424-1-git-send-email-xinhui.pan@linux.vnet.ibm.com> References: <1478077718-37424-1-git-send-email-xinhui.pan@linux.vnet.ibm.com> X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 16110205-0012-0000-0000-000001DE176D X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 16110205-0013-0000-0000-000006535823 Message-Id: <1478077718-37424-2-git-send-email-xinhui.pan@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2016-11-02_02:,, 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=8.0.1-1609300000 definitions=main-1611020096 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1469 Lines: 42 This patch support to fix lock holder preemption issue. For kernel users, we could use bool vcpu_is_preempted(int cpu) to detect if one vcpu is preempted or not. The default implementation is a macro defined by false. So compiler can wrap it out if arch dose not support such vcpu preempted check. Suggested-by: Peter Zijlstra (Intel) Signed-off-by: Pan Xinhui Acked-by: Christian Borntraeger Acked-by: Paolo Bonzini Tested-by: Juergen Gross --- include/linux/sched.h | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/include/linux/sched.h b/include/linux/sched.h index 348f51b..44c1ce7 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -3506,6 +3506,18 @@ static inline void set_task_cpu(struct task_struct *p, unsigned int cpu) #endif /* CONFIG_SMP */ +/* + * In order to deal with a various lock holder preemption issues provide an + * interface to see if a vCPU is currently running or not. + * + * This allows us to terminate optimistic spin loops and block, analogous to + * the native optimistic spin heuristic of testing if the lock owner task is + * running or not. + */ +#ifndef vcpu_is_preempted +#define vcpu_is_preempted(cpu) false +#endif + extern long sched_setaffinity(pid_t pid, const struct cpumask *new_mask); extern long sched_getaffinity(pid_t pid, struct cpumask *mask); -- 2.4.11