lkml.org 
[lkml]   [2011]   [Jan]   [28]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    SubjectRe: [PATCH v2 3/6] KVM-GST: KVM Steal time accounting
    From
    Date
    On Fri, 2011-01-28 at 17:16 -0800, Jeremy Fitzhardinge wrote:
    > On 01/28/2011 11:52 AM, Glauber Costa wrote:
    > > 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.
    >
    > Is this used on the host or guest side?

    Guest.

    > J
    >
    > > 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 <glommer@redhat.com>
    > > CC: Rik van Riel <riel@redhat.com>
    > > CC: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
    > > CC: Peter Zijlstra <peterz@infradead.org>
    > > CC: Avi Kivity <avi@redhat.com>
    > > ---
    > > include/linux/sched.h | 1 +
    > > kernel/sched.c | 41 +++++++++++++++++++++++++++++++++++++++++
    > > 2 files changed, 42 insertions(+), 0 deletions(-)
    > >
    > > diff --git a/include/linux/sched.h b/include/linux/sched.h
    > > index d747f94..77e9297 100644
    > > --- a/include/linux/sched.h
    > > +++ b/include/linux/sched.h
    > > @@ -302,6 +302,7 @@ long io_schedule_timeout(long timeout);
    > > extern void cpu_init (void);
    > > extern void trap_init(void);
    > > extern void update_process_times(int user);
    > > +extern u64 (*hypervisor_steal_time)(void);
    > > extern void scheduler_tick(void);
    > >
    > > extern void sched_show_task(struct task_struct *p);
    > > diff --git a/kernel/sched.c b/kernel/sched.c
    > > index ea3e5ef..7765e9d 100644
    > > --- a/kernel/sched.c
    > > +++ b/kernel/sched.c
    > > @@ -3508,6 +3508,39 @@ unsigned long long thread_group_sched_runtime(struct task_struct *p)
    > > return ns;
    > > }
    > >
    > > +u64 (*hypervisor_steal_time)(void) = NULL;
    > > +
    > > +/*
    > > + * 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 int touch_steal_time(int is_idle)
    > > +{
    > > + u64 steal, st;
    > > +
    > > + if (!hypervisor_steal_time)
    > > + return 0;
    > > +
    > > + steal = hypervisor_steal_time();
    > > +
    > > + st = usecs_to_cputime(steal / 1000);
    > > +
    > > + if (is_idle)
    > > + return 0;
    > > +
    > > + if (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
    > > @@ -3520,6 +3553,9 @@ 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);
    > > @@ -3580,6 +3616,9 @@ void account_system_time(struct task_struct *p, int hardirq_offset,
    > > struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;
    > > cputime64_t tmp;
    > >
    > > + if (touch_steal_time(0))
    > > + return;
    > > +
    > > if ((p->flags & PF_VCPU) && (irq_count() - hardirq_offset == 0)) {
    > > account_guest_time(p, cputime, cputime_scaled);
    > > return;
    > > @@ -3627,6 +3666,8 @@ 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
    >




    \
     
     \ /
      Last update: 2011-01-29 02:29    [W:0.028 / U:28.860 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site