From mboxrd@z Thu Jan  1 00:00:00 1970
From: Keir Fraser <keir@xen.org>
Subject: Re: [PATCH] xen,credit1: Add variable timeslice
Date: Tue, 13 Sep 2011 10:44:06 +0100
Message-ID: <CA94E476.31792%keir@xen.org>
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To: George Dunlap <George.Dunlap@eu.citrix.com>, xen-devel@lists.xensource.com
Cc: Tim Deegan <tim@xen.org>
List-Id: xen-devel@lists.xenproject.org

On 13/09/2011 10:25, "George Dunlap" <George.Dunlap@eu.citrix.com> wrote:

> Ping?

Now done.

 -- Keir

> On Thu, Sep 1, 2011 at 4:30 PM, George Dunlap
> <george.dunlap@eu.citrix.com> wrote:
>> Add a xen command-line parameter, sched_credit_tslice_ms,
>> to set the timeslice of the credit1 scheduler.
>>=20
>> Signed-off-by: George Dunlap <george.dunlap@eu.citrix.com>
>>=20
>> 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 @@
>> =A0*/
>> =A0#define CSCHED_DEFAULT_WEIGHT =A0 =A0 =A0 256
>> =A0#define CSCHED_TICKS_PER_TSLICE =A0 =A0 3
>> -#define CSCHED_TICKS_PER_ACCT =A0 =A0 =A0 3
>> -#define CSCHED_MSECS_PER_TICK =A0 =A0 =A0 10
>> -#define CSCHED_MSECS_PER_TSLICE =A0 =A0 \
>> - =A0 =A0(CSCHED_MSECS_PER_TICK * CSCHED_TICKS_PER_TSLICE)
>> +/* Default timeslice: 30ms */
>> +#define CSCHED_DEFAULT_TSLICE_MS =A0 =A030
>> =A0#define CSCHED_CREDITS_PER_MSEC =A0 =A0 10
>> -#define CSCHED_CREDITS_PER_TSLICE =A0 \
>> - =A0 =A0(CSCHED_CREDITS_PER_MSEC * CSCHED_MSECS_PER_TSLICE)
>> -#define CSCHED_CREDITS_PER_ACCT =A0 =A0 \
>> - =A0 =A0(CSCHED_CREDITS_PER_MSEC * CSCHED_MSECS_PER_TICK *
>> CSCHED_TICKS_PER_ACCT)
>>=20
>>=20
>> =A0/*
>> @@ -113,6 +107,8 @@
>> =A0*/
>> =A0static bool_t __read_mostly sched_credit_default_yield;
>> =A0boolean_param("sched_credit_default_yield", sched_credit_default_yield)=
;
>> +static int __read_mostly sched_credit_tslice_ms =3D CSCHED_DEFAULT_TSLICE=
_MS;
>> +integer_param("sched_credit_tslice_ms", sched_credit_tslice_ms);
>>=20
>> =A0/*
>> =A0* Physical CPU
>> @@ -176,6 +172,9 @@ struct csched_private {
>> =A0 =A0 uint32_t credit;
>> =A0 =A0 int credit_balance;
>> =A0 =A0 uint32_t runq_sort;
>> + =A0 =A0/* Period of master and tick in milliseconds */
>> + =A0 =A0unsigned tslice_ms, tick_period_us, ticks_per_tslice;
>> + =A0 =A0unsigned credits_per_tslice;
>> =A0};
>>=20
>> =A0static void csched_tick(void *_cpu);
>> @@ -326,7 +325,7 @@ csched_free_pdata(const struct scheduler
>>=20
>> =A0 =A0 spin_lock_irqsave(&prv->lock, flags);
>>=20
>> - =A0 =A0prv->credit -=3D CSCHED_CREDITS_PER_ACCT;
>> + =A0 =A0prv->credit -=3D prv->credits_per_tslice;
>> =A0 =A0 prv->ncpus--;
>> =A0 =A0 cpu_clear(cpu, prv->idlers);
>> =A0 =A0 cpu_clear(cpu, prv->cpus);
>> @@ -360,19 +359,19 @@ csched_alloc_pdata(const struct schedule
>> =A0 =A0 spin_lock_irqsave(&prv->lock, flags);
>>=20
>> =A0 =A0 /* Initialize/update system-wide config */
>> - =A0 =A0prv->credit +=3D CSCHED_CREDITS_PER_ACCT;
>> + =A0 =A0prv->credit +=3D prv->credits_per_tslice;
>> =A0 =A0 prv->ncpus++;
>> =A0 =A0 cpu_set(cpu, prv->cpus);
>> =A0 =A0 if ( prv->ncpus =3D=3D 1 )
>> =A0 =A0 {
>> =A0 =A0 =A0 =A0 prv->master =3D cpu;
>> =A0 =A0 =A0 =A0 init_timer(&prv->master_ticker, csched_acct, prv, cpu);
>> - =A0 =A0 =A0 =A0set_timer(&prv->master_ticker, NOW() +
>> - =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0MILLISECS(CSCHED_MSECS_PER_TICK) * CSCHED_TICKS_PER_A=
CCT);
>> + =A0 =A0 =A0 =A0set_timer(&prv->master_ticker,
>> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0NOW() + MILLISECS(prv->tslice_ms));
>> =A0 =A0 }
>>=20
>> =A0 =A0 init_timer(&spc->ticker, csched_tick, (void *)(unsigned long)cpu, cp=
u);
>> - =A0 =A0set_timer(&spc->ticker, NOW() + MILLISECS(CSCHED_MSECS_PER_TICK));
>> + =A0 =A0set_timer(&spc->ticker, NOW() + MICROSECS(prv->tick_period_us) );
>>=20
>> =A0 =A0 INIT_LIST_HEAD(&spc->runq);
>> =A0 =A0 spc->runq_sort_last =3D prv->runq_sort;
>> @@ -1002,7 +1001,7 @@ csched_acct(void* dummy)
>> =A0 =A0 =A0 =A0 =A0* for one full accounting period. We allow a domain to earn mor=
e
>> =A0 =A0 =A0 =A0 =A0* only when the system-wide credit balance is negative.
>> =A0 =A0 =A0 =A0 =A0*/
>> - =A0 =A0 =A0 =A0credit_peak =3D sdom->active_vcpu_count * CSCHED_CREDITS_PER_ACCT=
;
>> + =A0 =A0 =A0 =A0credit_peak =3D sdom->active_vcpu_count * prv->credits_per_tslice=
;
>> =A0 =A0 =A0 =A0 if ( prv->credit_balance < 0 )
>> =A0 =A0 =A0 =A0 {
>> =A0 =A0 =A0 =A0 =A0 =A0 credit_peak +=3D ( ( -prv->credit_balance
>> @@ -1014,7 +1013,7 @@ csched_acct(void* dummy)
>>=20
>> =A0 =A0 =A0 =A0 if ( sdom->cap !=3D 0U )
>> =A0 =A0 =A0 =A0 {
>> - =A0 =A0 =A0 =A0 =A0 =A0credit_cap =3D ((sdom->cap * CSCHED_CREDITS_PER_ACCT) + 99) /=
 100;
>> + =A0 =A0 =A0 =A0 =A0 =A0credit_cap =3D ((sdom->cap * prv->credits_per_tslice) + 99) /=
 100;
>> =A0 =A0 =A0 =A0 =A0 =A0 if ( credit_cap < credit_peak )
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 credit_peak =3D credit_cap;
>>=20
>> @@ -1092,10 +1091,10 @@ csched_acct(void* dummy)
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 }
>>=20
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 /* Lower bound on credits */
>> - =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0if ( credit < -CSCHED_CREDITS_PER_TSLICE )
>> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0if ( credit < -prv->credits_per_tslice )
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 {
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 CSCHED_STAT_CRANK(acct_min_credit);
>> - =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0credit =3D -CSCHED_CREDITS_PER_TSLICE;
>> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0credit =3D -prv->credits_per_tslice;
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 atomic_set(&svc->credit, credit);
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 }
>> =A0 =A0 =A0 =A0 =A0 =A0 }
>> @@ -1117,7 +1116,7 @@ csched_acct(void* dummy)
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 }
>>=20
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 /* Upper bound on credits means VCPU stops earning */
>> - =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0if ( credit > CSCHED_CREDITS_PER_TSLICE )
>> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0if ( credit > prv->credits_per_tslice )
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 {
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 __csched_vcpu_acct_stop_locked(prv, svc);
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 /* Divide credits in half, so that when it starts
>> @@ -1141,8 +1140,8 @@ csched_acct(void* dummy)
>> =A0 =A0 prv->runq_sort++;
>>=20
>> =A0out:
>> - =A0 =A0set_timer( &prv->master_ticker, NOW() +
>> - =A0 =A0 =A0 =A0 =A0 =A0MILLISECS(CSCHED_MSECS_PER_TICK) * CSCHED_TICKS_PER_ACCT );
>> + =A0 =A0set_timer( &prv->master_ticker,
>> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 NOW() + MILLISECS(prv->tslice_ms));
>> =A0}
>>=20
>> =A0static void
>> @@ -1169,7 +1168,7 @@ csched_tick(void *_cpu)
>> =A0 =A0 =A0*/
>> =A0 =A0 csched_runq_sort(prv, cpu);
>>=20
>> - =A0 =A0set_timer(&spc->ticker, NOW() + MILLISECS(CSCHED_MSECS_PER_TICK));
>> + =A0 =A0set_timer(&spc->ticker, NOW() + MICROSECS(prv->tick_period_us) );
>> =A0}
>>=20
>> =A0static struct csched_vcpu *
>> @@ -1375,7 +1374,7 @@ csched_schedule(
>> =A0 =A0 =A0* Return task to run next...
>> =A0 =A0 =A0*/
>> =A0 =A0 ret.time =3D (is_idle_vcpu(snext->vcpu) ?
>> - =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0-1 : MILLISECS(CSCHED_MSECS_PER_TSLICE));
>> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0-1 : MILLISECS(prv->tslice_ms));
>> =A0 =A0 ret.task =3D snext->vcpu;
>>=20
>> =A0 =A0 CSCHED_VCPU_CHECK(ret.task);
>> @@ -1469,10 +1468,9 @@ csched_dump(const struct scheduler *ops)
>> =A0 =A0 =A0 =A0 =A0 =A0"\tweight =A0 =A0 =A0 =A0 =A0 =A0 =3D %u\n"
>> =A0 =A0 =A0 =A0 =A0 =A0"\trunq_sort =A0 =A0 =A0 =A0 =A0=3D %u\n"
>> =A0 =A0 =A0 =A0 =A0 =A0"\tdefault-weight =A0 =A0 =3D %d\n"
>> - =A0 =A0 =A0 =A0 =A0 "\tmsecs per tick =A0 =A0 =3D %dms\n"
>> + =A0 =A0 =A0 =A0 =A0 "\ttslice =A0 =A0 =A0 =A0 =A0 =A0 =3D %dms\n"
>> =A0 =A0 =A0 =A0 =A0 =A0"\tcredits per msec =A0 =3D %d\n"
>> =A0 =A0 =A0 =A0 =A0 =A0"\tticks per tslice =A0 =3D %d\n"
>> - =A0 =A0 =A0 =A0 =A0 "\tticks per acct =A0 =A0 =3D %d\n"
>> =A0 =A0 =A0 =A0 =A0 =A0"\tmigration delay =A0 =A0=3D %uus\n",
>> =A0 =A0 =A0 =A0 =A0 =A0prv->ncpus,
>> =A0 =A0 =A0 =A0 =A0 =A0prv->master,
>> @@ -1481,10 +1479,9 @@ csched_dump(const struct scheduler *ops)
>> =A0 =A0 =A0 =A0 =A0 =A0prv->weight,
>> =A0 =A0 =A0 =A0 =A0 =A0prv->runq_sort,
>> =A0 =A0 =A0 =A0 =A0 =A0CSCHED_DEFAULT_WEIGHT,
>> - =A0 =A0 =A0 =A0 =A0 CSCHED_MSECS_PER_TICK,
>> + =A0 =A0 =A0 =A0 =A0 prv->tslice_ms,
>> =A0 =A0 =A0 =A0 =A0 =A0CSCHED_CREDITS_PER_MSEC,
>> - =A0 =A0 =A0 =A0 =A0 CSCHED_TICKS_PER_TSLICE,
>> - =A0 =A0 =A0 =A0 =A0 CSCHED_TICKS_PER_ACCT,
>> + =A0 =A0 =A0 =A0 =A0 prv->ticks_per_tslice,
>> =A0 =A0 =A0 =A0 =A0 =A0vcpu_migration_delay);
>>=20
>> =A0 =A0 cpumask_scnprintf(idlers_buf, sizeof(idlers_buf), prv->idlers);
>> @@ -1526,6 +1523,13 @@ csched_init(struct scheduler *ops)
>> =A0 =A0 INIT_LIST_HEAD(&prv->active_sdom);
>> =A0 =A0 prv->master =3D UINT_MAX;
>>=20
>> + =A0 =A0prv->tslice_ms =3D sched_credit_tslice_ms;
>> + =A0 =A0prv->ticks_per_tslice =3D CSCHED_TICKS_PER_TSLICE;
>> + =A0 =A0if ( prv->tslice_ms < prv->ticks_per_tslice )
>> + =A0 =A0 =A0 =A0prv->ticks_per_tslice =3D 1;
>> + =A0 =A0prv->tick_period_us =3D prv->tslice_ms * 1000 / prv->ticks_per_tslice=
;
>> + =A0 =A0prv->credits_per_tslice =3D CSCHED_CREDITS_PER_MSEC * prv->tslice_ms;
>> +
>> =A0 =A0 return 0;
>> =A0}
>>=20
>> @@ -1550,13 +1554,16 @@ static void csched_tick_suspend(const st
>>=20
>> =A0static void csched_tick_resume(const struct scheduler *ops, unsigned in=
t
>> cpu)
>> =A0{
>> + =A0 =A0struct csched_private *prv;
>> =A0 =A0 struct csched_pcpu *spc;
>> =A0 =A0 uint64_t now =3D NOW();
>>=20
>> =A0 =A0 spc =3D CSCHED_PCPU(cpu);
>>=20
>> - =A0 =A0set_timer(&spc->ticker, now + MILLISECS(CSCHED_MSECS_PER_TICK)
>> - =A0 =A0 =A0 =A0 =A0 =A0- now % MILLISECS(CSCHED_MSECS_PER_TICK) );
>> + =A0 =A0prv =3D CSCHED_PRIV(ops);
>> +
>> + =A0 =A0set_timer(&spc->ticker, now + MICROSECS(prv->tick_period_us)
>> + =A0 =A0 =A0 =A0 =A0 =A0- now % MICROSECS(prv->tick_period_us) );
>> =A0}
>>=20
>> =A0static struct csched_private _csched_priv;
>>=20
>> _______________________________________________
>> Xen-devel mailing list
>> Xen-devel@lists.xensource.com
>> http://lists.xensource.com/xen-devel
>>=20