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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH] xen,credit1: Add variable timeslice
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On Thu, Sep 1, 2011 at 4:30 PM, George Dunlap
<george.dunlap@xxxxxxxxxxxxx> wrote:
> Add a xen command-line parameter, sched_credit_tslice_ms,
> to set the timeslice of the credit1 scheduler.
>
> Signed-off-by: George Dunlap <george.dunlap@xxxxxxxxxxxxx>
>
> diff -r 4a4882df5649 -r 782284c5b1bc xen/common/sched_credit.c
> --- a/xen/common/sched_credit.c Wed Aug 31 15:23:49 2011 +0100
> +++ b/xen/common/sched_credit.c Thu Sep 01 16:29:50 2011 +0100
> @@ -41,15 +41,9 @@
> */
> #define CSCHED_DEFAULT_WEIGHT 256
> #define CSCHED_TICKS_PER_TSLICE 3
> -#define CSCHED_TICKS_PER_ACCT 3
> -#define CSCHED_MSECS_PER_TICK 10
> -#define CSCHED_MSECS_PER_TSLICE \
> - (CSCHED_MSECS_PER_TICK * CSCHED_TICKS_PER_TSLICE)
> +/* Default timeslice: 30ms */
> +#define CSCHED_DEFAULT_TSLICE_MS 30
> #define CSCHED_CREDITS_PER_MSEC 10
> -#define CSCHED_CREDITS_PER_TSLICE \
> - (CSCHED_CREDITS_PER_MSEC * CSCHED_MSECS_PER_TSLICE)
> -#define CSCHED_CREDITS_PER_ACCT \
> - (CSCHED_CREDITS_PER_MSEC * CSCHED_MSECS_PER_TICK * CSCHED_TICKS_PER_ACCT)
>
>
> /*
> @@ -113,6 +107,8 @@
> */
> static bool_t __read_mostly sched_credit_default_yield;
> boolean_param("sched_credit_default_yield", sched_credit_default_yield);
> +static int __read_mostly sched_credit_tslice_ms = CSCHED_DEFAULT_TSLICE_MS;
> +integer_param("sched_credit_tslice_ms", sched_credit_tslice_ms);
>
> /*
> * Physical CPU
> @@ -176,6 +172,9 @@ struct csched_private {
> uint32_t credit;
> int credit_balance;
> uint32_t runq_sort;
> + /* Period of master and tick in milliseconds */
> + unsigned tslice_ms, tick_period_us, ticks_per_tslice;
> + unsigned credits_per_tslice;
> };
>
> static void csched_tick(void *_cpu);
> @@ -326,7 +325,7 @@ csched_free_pdata(const struct scheduler
>
> spin_lock_irqsave(&prv->lock, flags);
>
> - prv->credit -= CSCHED_CREDITS_PER_ACCT;
> + prv->credit -= prv->credits_per_tslice;
> prv->ncpus--;
> cpu_clear(cpu, prv->idlers);
> cpu_clear(cpu, prv->cpus);
> @@ -360,19 +359,19 @@ csched_alloc_pdata(const struct schedule
> spin_lock_irqsave(&prv->lock, flags);
>
> /* Initialize/update system-wide config */
> - prv->credit += CSCHED_CREDITS_PER_ACCT;
> + prv->credit += prv->credits_per_tslice;
> prv->ncpus++;
> cpu_set(cpu, prv->cpus);
> if ( prv->ncpus == 1 )
> {
> prv->master = cpu;
> init_timer(&prv->master_ticker, csched_acct, prv, cpu);
> - set_timer(&prv->master_ticker, NOW() +
> - MILLISECS(CSCHED_MSECS_PER_TICK) * CSCHED_TICKS_PER_ACCT);
> + set_timer(&prv->master_ticker,
> + NOW() + MILLISECS(prv->tslice_ms));
> }
>
> init_timer(&spc->ticker, csched_tick, (void *)(unsigned long)cpu, cpu);
> - set_timer(&spc->ticker, NOW() + MILLISECS(CSCHED_MSECS_PER_TICK));
> + set_timer(&spc->ticker, NOW() + MICROSECS(prv->tick_period_us) );
>
> INIT_LIST_HEAD(&spc->runq);
> spc->runq_sort_last = prv->runq_sort;
> @@ -1002,7 +1001,7 @@ csched_acct(void* dummy)
> * for one full accounting period. We allow a domain to earn more
> * only when the system-wide credit balance is negative.
> */
> - credit_peak = sdom->active_vcpu_count * CSCHED_CREDITS_PER_ACCT;
> + credit_peak = sdom->active_vcpu_count * prv->credits_per_tslice;
> if ( prv->credit_balance < 0 )
> {
> credit_peak += ( ( -prv->credit_balance
> @@ -1014,7 +1013,7 @@ csched_acct(void* dummy)
>
> if ( sdom->cap != 0U )
> {
> - credit_cap = ((sdom->cap * CSCHED_CREDITS_PER_ACCT) + 99) / 100;
> + credit_cap = ((sdom->cap * prv->credits_per_tslice) + 99) / 100;
> if ( credit_cap < credit_peak )
> credit_peak = credit_cap;
>
> @@ -1092,10 +1091,10 @@ csched_acct(void* dummy)
> }
>
> /* Lower bound on credits */
> - if ( credit < -CSCHED_CREDITS_PER_TSLICE )
> + if ( credit < -prv->credits_per_tslice )
> {
> CSCHED_STAT_CRANK(acct_min_credit);
> - credit = -CSCHED_CREDITS_PER_TSLICE;
> + credit = -prv->credits_per_tslice;
> atomic_set(&svc->credit, credit);
> }
> }
> @@ -1117,7 +1116,7 @@ csched_acct(void* dummy)
> }
>
> /* Upper bound on credits means VCPU stops earning */
> - if ( credit > CSCHED_CREDITS_PER_TSLICE )
> + if ( credit > prv->credits_per_tslice )
> {
> __csched_vcpu_acct_stop_locked(prv, svc);
> /* Divide credits in half, so that when it starts
> @@ -1141,8 +1140,8 @@ csched_acct(void* dummy)
> prv->runq_sort++;
>
> out:
> - set_timer( &prv->master_ticker, NOW() +
> - MILLISECS(CSCHED_MSECS_PER_TICK) * CSCHED_TICKS_PER_ACCT );
> + set_timer( &prv->master_ticker,
> + NOW() + MILLISECS(prv->tslice_ms));
> }
>
> static void
> @@ -1169,7 +1168,7 @@ csched_tick(void *_cpu)
> */
> csched_runq_sort(prv, cpu);
>
> - set_timer(&spc->ticker, NOW() + MILLISECS(CSCHED_MSECS_PER_TICK));
> + set_timer(&spc->ticker, NOW() + MICROSECS(prv->tick_period_us) );
> }
>
> static struct csched_vcpu *
> @@ -1375,7 +1374,7 @@ csched_schedule(
> * Return task to run next...
> */
> ret.time = (is_idle_vcpu(snext->vcpu) ?
> - -1 : MILLISECS(CSCHED_MSECS_PER_TSLICE));
> + -1 : MILLISECS(prv->tslice_ms));
> ret.task = snext->vcpu;
>
> CSCHED_VCPU_CHECK(ret.task);
> @@ -1469,10 +1468,9 @@ csched_dump(const struct scheduler *ops)
> "\tweight = %u\n"
> "\trunq_sort = %u\n"
> "\tdefault-weight = %d\n"
> - "\tmsecs per tick = %dms\n"
> + "\ttslice = %dms\n"
> "\tcredits per msec = %d\n"
> "\tticks per tslice = %d\n"
> - "\tticks per acct = %d\n"
> "\tmigration delay = %uus\n",
> prv->ncpus,
> prv->master,
> @@ -1481,10 +1479,9 @@ csched_dump(const struct scheduler *ops)
> prv->weight,
> prv->runq_sort,
> CSCHED_DEFAULT_WEIGHT,
> - CSCHED_MSECS_PER_TICK,
> + prv->tslice_ms,
> CSCHED_CREDITS_PER_MSEC,
> - CSCHED_TICKS_PER_TSLICE,
> - CSCHED_TICKS_PER_ACCT,
> + prv->ticks_per_tslice,
> vcpu_migration_delay);
>
> cpumask_scnprintf(idlers_buf, sizeof(idlers_buf), prv->idlers);
> @@ -1526,6 +1523,13 @@ csched_init(struct scheduler *ops)
> INIT_LIST_HEAD(&prv->active_sdom);
> prv->master = UINT_MAX;
>
> + prv->tslice_ms = sched_credit_tslice_ms;
> + prv->ticks_per_tslice = CSCHED_TICKS_PER_TSLICE;
> + if ( prv->tslice_ms < prv->ticks_per_tslice )
> + prv->ticks_per_tslice = 1;
> + prv->tick_period_us = prv->tslice_ms * 1000 / prv->ticks_per_tslice;
> + prv->credits_per_tslice = CSCHED_CREDITS_PER_MSEC * prv->tslice_ms;
> +
> return 0;
> }
>
> @@ -1550,13 +1554,16 @@ static void csched_tick_suspend(const st
>
> static void csched_tick_resume(const struct scheduler *ops, unsigned int cpu)
> {
> + struct csched_private *prv;
> struct csched_pcpu *spc;
> uint64_t now = NOW();
>
> spc = CSCHED_PCPU(cpu);
>
> - set_timer(&spc->ticker, now + MILLISECS(CSCHED_MSECS_PER_TICK)
> - - now % MILLISECS(CSCHED_MSECS_PER_TICK) );
> + prv = CSCHED_PRIV(ops);
> +
> + set_timer(&spc->ticker, now + MICROSECS(prv->tick_period_us)
> + - now % MICROSECS(prv->tick_period_us) );
> }
>
> static struct csched_private _csched_priv;
>
> _______________________________________________
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> Xen-devel@xxxxxxxxxxxxxxxxxxx
> http://lists.xensource.com/xen-devel
>
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