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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH] xen,credit1: Add variable timeslice
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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