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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v2 06/10] xen: tracing: add trace records for schedule and rate-limiting.
On 30/09/16 03:54, Dario Faggioli wrote:
> As far as {csched, csched2, rt}_schedule() are concerned,
> an "empty" event, would already make it easier to read and
> understand a trace.
>
> But while there, add a few useful information, like
> if the cpu that is going through the scheduler has
> been tickled or not, if it is currently idle, etc
> (they vary, on a per-scheduler basis).
>
> For Credit1 and Credit2, add a record about when
> rate-limiting kicks in too.
>
> Signed-off-by: Dario Faggioli <dario.faggioli@xxxxxxxxxx>
Acked-by: George Dunlap <george.dunlap@xxxxxxxxxx>
> ---
> Cc: George Dunlap <george.dunlap@xxxxxxxxxxxxx>
> Cc: Meng Xu <mengxu@xxxxxxxxxxxxx>
> Cc: Anshul Makkar <anshul.makkar@xxxxxxxxxx>
> ---
> Changes from v1:
> * corrected the schedule record for sched_rt.c, as pointed out during review;
> * pack the Credit1 records as well, as requested during review.
> ---
> xen/common/sched_credit.c | 32 ++++++++++++++++++++++++++++++++
> xen/common/sched_credit2.c | 40 +++++++++++++++++++++++++++++++++++++++-
> xen/common/sched_rt.c | 15 +++++++++++++++
> 3 files changed, 86 insertions(+), 1 deletion(-)
>
> diff --git a/xen/common/sched_credit.c b/xen/common/sched_credit.c
> index 5700763..fc3a321 100644
> --- a/xen/common/sched_credit.c
> +++ b/xen/common/sched_credit.c
> @@ -133,6 +133,8 @@
> #define TRC_CSCHED_TICKLE TRC_SCHED_CLASS_EVT(CSCHED, 6)
> #define TRC_CSCHED_BOOST_START TRC_SCHED_CLASS_EVT(CSCHED, 7)
> #define TRC_CSCHED_BOOST_END TRC_SCHED_CLASS_EVT(CSCHED, 8)
> +#define TRC_CSCHED_SCHEDULE TRC_SCHED_CLASS_EVT(CSCHED, 9)
> +#define TRC_CSCHED_RATELIMIT TRC_SCHED_CLASS_EVT(CSCHED, 10)
>
>
> /*
> @@ -1774,6 +1776,23 @@ csched_schedule(
> SCHED_STAT_CRANK(schedule);
> CSCHED_VCPU_CHECK(current);
>
> + /*
> + * Here in Credit1 code, we usually just call TRACE_nD() helpers, and
> + * don't care about packing. But scheduling happens very often, so it
> + * actually is important that the record is as small as possible.
> + */
> + if ( unlikely(tb_init_done) )
> + {
> + struct {
> + unsigned cpu:16, tasklet:8, idle:8;
> + } d;
> + d.cpu = cpu;
> + d.tasklet = tasklet_work_scheduled;
> + d.idle = is_idle_vcpu(current);
> + __trace_var(TRC_CSCHED_SCHEDULE, 1, sizeof(d),
> + (unsigned char *)&d);
> + }
> +
> runtime = now - current->runstate.state_entry_time;
> if ( runtime < 0 ) /* Does this ever happen? */
> runtime = 0;
> @@ -1829,6 +1848,19 @@ csched_schedule(
> tslice = MICROSECS(prv->ratelimit_us) - runtime;
> if ( unlikely(runtime < CSCHED_MIN_TIMER) )
> tslice = CSCHED_MIN_TIMER;
> + if ( unlikely(tb_init_done) )
> + {
> + struct {
> + unsigned vcpu:16, dom:16;
> + unsigned runtime;
> + } d;
> + d.dom = scurr->vcpu->domain->domain_id;
> + d.vcpu = scurr->vcpu->vcpu_id;
> + d.runtime = runtime;
> + __trace_var(TRC_CSCHED_RATELIMIT, 1, sizeof(d),
> + (unsigned char *)&d);
> + }
> +
> ret.migrated = 0;
> goto out;
> }
> diff --git a/xen/common/sched_credit2.c b/xen/common/sched_credit2.c
> index fde61ef..5cf3f16 100644
> --- a/xen/common/sched_credit2.c
> +++ b/xen/common/sched_credit2.c
> @@ -55,6 +55,8 @@
> #define TRC_CSCHED2_LOAD_BALANCE TRC_SCHED_CLASS_EVT(CSCHED2, 17)
> #define TRC_CSCHED2_PICKED_CPU TRC_SCHED_CLASS_EVT(CSCHED2, 19)
> #define TRC_CSCHED2_RUNQ_CANDIDATE TRC_SCHED_CLASS_EVT(CSCHED2, 20)
> +#define TRC_CSCHED2_SCHEDULE TRC_SCHED_CLASS_EVT(CSCHED2, 21)
> +#define TRC_CSCHED2_RATELIMIT TRC_SCHED_CLASS_EVT(CSCHED2, 22)
>
> /*
> * WARNING: This is still in an experimental phase. Status and work can be
> found at the
> @@ -2288,12 +2290,29 @@ runq_candidate(struct csched2_runqueue_data *rqd,
> * no point forcing it to do so until rate limiting expires.
> */
> if ( __test_and_clear_bit(__CSFLAG_vcpu_yield, &scurr->flags) )
> + {
> yield_bias = CSCHED2_YIELD_BIAS;
> + }
> else if ( prv->ratelimit_us && !is_idle_vcpu(scurr->vcpu) &&
> vcpu_runnable(scurr->vcpu) &&
> (now - scurr->vcpu->runstate.state_entry_time) <
> MICROSECS(prv->ratelimit_us) )
> + {
> + if ( unlikely(tb_init_done) )
> + {
> + struct {
> + unsigned vcpu:16, dom:16;
> + unsigned runtime;
> + } d;
> + d.dom = scurr->vcpu->domain->domain_id;
> + d.vcpu = scurr->vcpu->vcpu_id;
> + d.runtime = now - scurr->vcpu->runstate.state_entry_time;
> + __trace_var(TRC_CSCHED2_RATELIMIT, 1,
> + sizeof(d),
> + (unsigned char *)&d);
> + }
> return scurr;
> + }
>
> /* Default to current if runnable, idle otherwise */
> if ( vcpu_runnable(scurr->vcpu) )
> @@ -2383,6 +2402,7 @@ csched2_schedule(
> struct csched2_vcpu *snext = NULL;
> unsigned int skipped_vcpus = 0;
> struct task_slice ret;
> + bool_t tickled;
>
> SCHED_STAT_CRANK(schedule);
> CSCHED2_VCPU_CHECK(current);
> @@ -2397,13 +2417,31 @@ csched2_schedule(
> BUG_ON(!is_idle_vcpu(scurr->vcpu) && scurr->rqd != rqd);
>
> /* Clear "tickled" bit now that we've been scheduled */
> - if ( cpumask_test_cpu(cpu, &rqd->tickled) )
> + tickled = cpumask_test_cpu(cpu, &rqd->tickled);
> + if ( tickled )
> {
> __cpumask_clear_cpu(cpu, &rqd->tickled);
> cpumask_andnot(cpumask_scratch, &rqd->idle, &rqd->tickled);
> smt_idle_mask_set(cpu, cpumask_scratch, &rqd->smt_idle);
> }
>
> + if ( unlikely(tb_init_done) )
> + {
> + struct {
> + unsigned cpu:16, rq_id:16;
> + unsigned tasklet:8, idle:8, smt_idle:8, tickled:8;
> + } d;
> + d.cpu = cpu;
> + d.rq_id = c2r(ops, cpu);
> + d.tasklet = tasklet_work_scheduled;
> + d.idle = is_idle_vcpu(current);
> + d.smt_idle = cpumask_test_cpu(cpu, &rqd->smt_idle);
> + d.tickled = tickled;
> + __trace_var(TRC_CSCHED2_SCHEDULE, 1,
> + sizeof(d),
> + (unsigned char *)&d);
> + }
> +
> /* Update credits */
> burn_credits(rqd, scurr, now);
>
> diff --git a/xen/common/sched_rt.c b/xen/common/sched_rt.c
> index 41c61a7..d95f798 100644
> --- a/xen/common/sched_rt.c
> +++ b/xen/common/sched_rt.c
> @@ -160,6 +160,7 @@
> #define TRC_RTDS_BUDGET_BURN TRC_SCHED_CLASS_EVT(RTDS, 3)
> #define TRC_RTDS_BUDGET_REPLENISH TRC_SCHED_CLASS_EVT(RTDS, 4)
> #define TRC_RTDS_SCHED_TASKLET TRC_SCHED_CLASS_EVT(RTDS, 5)
> +#define TRC_RTDS_SCHEDULE TRC_SCHED_CLASS_EVT(RTDS, 6)
>
> static void repl_timer_handler(void *data);
>
> @@ -1035,6 +1036,20 @@ rt_schedule(const struct scheduler *ops, s_time_t now,
> bool_t tasklet_work_sched
> struct rt_vcpu *snext = NULL;
> struct task_slice ret = { .migrated = 0 };
>
> + /* TRACE */
> + {
> + struct __packed {
> + unsigned cpu:16, tasklet:8, tickled:4, idle:4;
> + } d;
> + d.cpu = cpu;
> + d.tasklet = tasklet_work_scheduled;
> + d.tickled = cpumask_test_cpu(cpu, &prv->tickled);
> + d.idle = is_idle_vcpu(current);
> + trace_var(TRC_RTDS_SCHEDULE, 1,
> + sizeof(d),
> + (unsigned char *)&d);
> + }
> +
> /* clear ticked bit now that we've been scheduled */
> cpumask_clear_cpu(cpu, &prv->tickled);
>
>
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