Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758953AbZJNTb2 (ORCPT ); Wed, 14 Oct 2009 15:31:28 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1759199AbZJNTa6 (ORCPT ); Wed, 14 Oct 2009 15:30:58 -0400 Received: from claw.goop.org ([74.207.240.146]:55339 "EHLO claw.goop.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759085AbZJNT36 (ORCPT ); Wed, 14 Oct 2009 15:29:58 -0400 From: Jeremy Fitzhardinge To: Linux Kernel Mailing List Cc: Xen-devel , kurt.hackel@oracle.com, Glauber de Oliveira Costa , Avi Kivity , the arch/x86 maintainers , Chris Mason , Jeremy Fitzhardinge , Peter Zijlstra , Ingo Molnar , Andi Kleen Subject: [PATCH 09/12] sched: add notifier for cross-cpu migrations Date: Wed, 14 Oct 2009 12:28:33 -0700 Message-Id: <1255548516-15260-10-git-send-email-jeremy.fitzhardinge@citrix.com> X-Mailer: git-send-email 1.6.2.5 In-Reply-To: <1255548516-15260-1-git-send-email-jeremy.fitzhardinge@citrix.com> References: <1255548516-15260-1-git-send-email-jeremy.fitzhardinge@citrix.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2659 Lines: 81 Add a notifier to publish when a task gets migrated from one cpu to another. The first intended use is to export a "migration counter" to usermode so that a task can tell whether its still running on the same cpu (for use in vgetcpu and other vsyscall code). Signed-off-by: Jeremy Fitzhardinge Cc: Avi Kivity Cc: Peter Zijlstra Cc: Ingo Molnar Cc: Andi Kleen --- include/linux/sched.h | 8 ++++++++ kernel/sched.c | 14 ++++++++++++++ 2 files changed, 22 insertions(+), 0 deletions(-) diff --git a/include/linux/sched.h b/include/linux/sched.h index 0f1ea4a..5186dd9 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -141,6 +141,14 @@ extern unsigned long nr_iowait(void); extern void calc_global_load(void); extern u64 cpu_nr_migrations(int cpu); +/* Notifier for when a task gets migrated to a new CPU */ +struct task_migration_notifier { + struct task_struct *task; + int from_cpu; + int to_cpu; +}; +extern void register_task_migration_notifier(struct notifier_block *n); + extern unsigned long get_parent_ip(unsigned long addr); struct seq_file; diff --git a/kernel/sched.c b/kernel/sched.c index 1b59e26..3982e8e 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -1951,6 +1951,12 @@ task_hot(struct task_struct *p, u64 now, struct sched_domain *sd) return delta < (s64)sysctl_sched_migration_cost; } +static ATOMIC_NOTIFIER_HEAD(task_migration_notifier); + +void register_task_migration_notifier(struct notifier_block *n) +{ + atomic_notifier_chain_register(&task_migration_notifier, n); +} void set_task_cpu(struct task_struct *p, unsigned int new_cpu) { @@ -1973,6 +1979,8 @@ void set_task_cpu(struct task_struct *p, unsigned int new_cpu) p->se.block_start -= clock_offset; #endif if (old_cpu != new_cpu) { + struct task_migration_notifier tmn; + p->se.nr_migrations++; new_rq->nr_migrations_in++; #ifdef CONFIG_SCHEDSTATS @@ -1981,6 +1989,12 @@ void set_task_cpu(struct task_struct *p, unsigned int new_cpu) #endif perf_swcounter_event(PERF_COUNT_SW_CPU_MIGRATIONS, 1, 1, NULL, 0); + + tmn.task = p; + tmn.from_cpu = old_cpu; + tmn.to_cpu = new_cpu; + + atomic_notifier_call_chain(&task_migration_notifier, 0, &tmn); } p->se.vruntime -= old_cfsrq->min_vruntime - new_cfsrq->min_vruntime; -- 1.6.2.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/