From patchwork Mon Jun 13 23:31:35 2011 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Glauber Costa X-Patchwork-Id: 877122 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by demeter1.kernel.org (8.14.4/8.14.4) with ESMTP id p5DNeSfX025041 for ; Mon, 13 Jun 2011 23:41:29 GMT Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755505Ab1FMXks (ORCPT ); Mon, 13 Jun 2011 19:40:48 -0400 Received: from mx1.redhat.com ([209.132.183.28]:20082 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755411Ab1FMXjA (ORCPT ); Mon, 13 Jun 2011 19:39:00 -0400 Received: from int-mx10.intmail.prod.int.phx2.redhat.com (int-mx10.intmail.prod.int.phx2.redhat.com [10.5.11.23]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id p5DNcsci002695 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK); Mon, 13 Jun 2011 19:38:54 -0400 Received: from virtlab1.virt.bos.redhat.com (virtlab1.virt.bos.redhat.com [10.16.72.21]) by int-mx10.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id p5DNcm4U015978; Mon, 13 Jun 2011 19:38:53 -0400 From: Glauber Costa To: kvm@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Rik van Riel , Jeremy Fitzhardinge , Peter Zijlstra , Avi Kivity , Anthony Liguori , Eric B Munson Subject: [PATCH 5/7] KVM-GST: KVM Steal time accounting Date: Mon, 13 Jun 2011 19:31:35 -0400 Message-Id: <1308007897-17013-6-git-send-email-glommer@redhat.com> In-Reply-To: <1308007897-17013-1-git-send-email-glommer@redhat.com> References: <1308007897-17013-1-git-send-email-glommer@redhat.com> X-Scanned-By: MIMEDefang 2.68 on 10.5.11.23 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org This patch accounts steal time time in kernel/sched. I kept it from last proposal, because I still see advantages in it: Doing it here will give us easier access from scheduler variables such as the cpu rq. The next patch shows an example of usage for it. Since functions like account_idle_time() can be called from multiple places, not only account_process_tick(), steal time grabbing is repeated in each account function separatedely. Signed-off-by: Glauber Costa CC: Rik van Riel CC: Jeremy Fitzhardinge CC: Peter Zijlstra CC: Avi Kivity CC: Anthony Liguori CC: Eric B Munson Tested-by: Eric B Munson --- kernel/sched.c | 45 +++++++++++++++++++++++++++++++++++++++++++++ 1 files changed, 45 insertions(+), 0 deletions(-) diff --git a/kernel/sched.c b/kernel/sched.c index 3f2e502..154cb14 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -75,6 +75,7 @@ #include #include #include +#include #include "sched_cpupri.h" #include "workqueue_sched.h" @@ -528,6 +529,7 @@ struct rq { #ifdef CONFIG_IRQ_TIME_ACCOUNTING u64 prev_irq_time; #endif + u64 prev_steal_time; /* calc_load related fields */ unsigned long calc_load_update; @@ -3705,6 +3707,41 @@ unsigned long long thread_group_sched_runtime(struct task_struct *p) } /* + * We have to at flush steal time information every time something else + * is accounted. Since the accounting functions are all visible to the rest + * of the kernel, it gets tricky to do them in one place. This helper function + * helps us. + * + * When the system is idle, the concept of steal time does not apply. We just + * tell the underlying hypervisor that we grabbed the data, but skip steal time + * accounting + */ +static inline int touch_steal_time(int is_idle) +{ + u64 steal, st = 0; + + if (static_branch(¶virt_steal_enabled)) { + + steal = paravirt_steal_clock(smp_processor_id()); + + steal -= this_rq()->prev_steal_time; + this_rq()->prev_steal_time += steal; + + if (is_idle || (steal < TICK_NSEC)) + return 0; + + while (steal > TICK_NSEC) { + steal -= TICK_NSEC; + st++; + } + + account_steal_time(st); + return 1; + } + return 0; +} + +/* * Account user cpu time to a process. * @p: the process that the cpu time gets accounted to * @cputime: the cpu time spent in user space since the last update @@ -3716,6 +3753,9 @@ void account_user_time(struct task_struct *p, cputime_t cputime, struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat; cputime64_t tmp; + if (touch_steal_time(0)) + return; + /* Add user time to process. */ p->utime = cputime_add(p->utime, cputime); p->utimescaled = cputime_add(p->utimescaled, cputime_scaled); @@ -3802,6 +3842,9 @@ void account_system_time(struct task_struct *p, int hardirq_offset, struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat; cputime64_t *target_cputime64; + if (touch_steal_time(0)) + return; + if ((p->flags & PF_VCPU) && (irq_count() - hardirq_offset == 0)) { account_guest_time(p, cputime, cputime_scaled); return; @@ -3839,6 +3882,8 @@ void account_idle_time(cputime_t cputime) cputime64_t cputime64 = cputime_to_cputime64(cputime); struct rq *rq = this_rq(); + touch_steal_time(1); + if (atomic_read(&rq->nr_iowait) > 0) cpustat->iowait = cputime64_add(cpustat->iowait, cputime64); else