[PATCH v2 1/5] xen: sched/credit: convert scheduling parameter to s_time_t when set

[Dario Faggioli <dfaggioli@suse.com>]

Basically, instead of converting integers to s_time_t
at usage time (hot paths), do the convertion when the
values are set (cold paths).

This applies to the timeslice and the ratelimit
parameters of Credit1.

Note that, when changing the type of the fields of
struct csched_private (from unsigned to s_time_t),
ncpus is moved up a bit, for better packing.

Signed-off-by: Dario Faggioli <dfaggioli@suse.com>
---
Cc: George Dunlap <george.dunlap@eu.citrix.com>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>
---
 xen/common/sched_credit.c |   56 ++++++++++++++++++++++-----------------------
 1 file changed, 27 insertions(+), 29 deletions(-)

diff --git a/xen/common/sched_credit.c b/xen/common/sched_credit.c
index f8212db5fe..a2c5d43e33 100644
--- a/xen/common/sched_credit.c
+++ b/xen/common/sched_credit.c
@@ -210,11 +210,11 @@ struct csched_private {
     cpumask_var_t cpus;
     uint32_t *balance_bias;
     uint32_t runq_sort;
-    unsigned int ratelimit_us;
+    uint32_t ncpus;
 
     /* Period of master and tick in milliseconds */
-    unsigned int tslice_ms, tick_period_us, ticks_per_tslice;
-    uint32_t ncpus;
+    unsigned int tick_period_us, ticks_per_tslice;
+    s_time_t ratelimit, tslice;
 
     struct list_head active_sdom;
     uint32_t weight;
@@ -570,8 +570,7 @@ init_pdata(struct csched_private *prv, struct csched_pcpu *spc, int cpu)
     {
         prv->master = cpu;
         init_timer(&prv->master_ticker, csched_acct, prv, cpu);
-        set_timer(&prv->master_ticker,
-                  NOW() + MILLISECS(prv->tslice_ms));
+        set_timer(&prv->master_ticker, NOW() + prv->tslice);
     }
 
     cpumask_and(cpumask_scratch, prv->cpus, &node_to_cpumask(cpu_to_node(cpu)));
@@ -1224,14 +1223,14 @@ csched_dom_cntl(
 }
 
 static inline void
-__csched_set_tslice(struct csched_private *prv, unsigned timeslice)
+__csched_set_tslice(struct csched_private *prv, unsigned int timeslice_ms)
 {
-    prv->tslice_ms = timeslice;
+    prv->tslice = MILLISECS(timeslice_ms);
     prv->ticks_per_tslice = CSCHED_TICKS_PER_TSLICE;
-    if ( prv->tslice_ms < prv->ticks_per_tslice )
+    if ( timeslice_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;
+    prv->tick_period_us = timeslice_ms * 1000 / prv->ticks_per_tslice;
+    prv->credits_per_tslice = CSCHED_CREDITS_PER_MSEC * timeslice_ms;
     prv->credit = prv->credits_per_tslice * prv->ncpus;
 }
 
@@ -1257,17 +1256,17 @@ csched_sys_cntl(const struct scheduler *ops,
 
         spin_lock_irqsave(&prv->lock, flags);
         __csched_set_tslice(prv, params->tslice_ms);
-        if ( !prv->ratelimit_us && params->ratelimit_us )
+        if ( !prv->ratelimit && params->ratelimit_us )
             printk(XENLOG_INFO "Enabling context switch rate limiting\n");
-        else if ( prv->ratelimit_us && !params->ratelimit_us )
+        else if ( prv->ratelimit && !params->ratelimit_us )
             printk(XENLOG_INFO "Disabling context switch rate limiting\n");
-        prv->ratelimit_us = params->ratelimit_us;
+        prv->ratelimit = MICROSECS(params->ratelimit_us);
         spin_unlock_irqrestore(&prv->lock, flags);
 
         /* FALLTHRU */
     case XEN_SYSCTL_SCHEDOP_getinfo:
-        params->tslice_ms = prv->tslice_ms;
-        params->ratelimit_us = prv->ratelimit_us;
+        params->tslice_ms = prv->tslice / MILLISECS(1);
+        params->ratelimit_us = prv->ratelimit / MICROSECS(1);
         rc = 0;
         break;
     }
@@ -1576,8 +1575,7 @@ csched_acct(void* dummy)
     prv->runq_sort++;
 
 out:
-    set_timer( &prv->master_ticker,
-               NOW() + MILLISECS(prv->tslice_ms));
+    set_timer( &prv->master_ticker, NOW() + prv->tslice);
 }
 
 static void
@@ -1901,21 +1899,21 @@ csched_schedule(
      */
     if ( !test_bit(CSCHED_FLAG_VCPU_YIELD, &scurr->flags)
          && !tasklet_work_scheduled
-         && prv->ratelimit_us
+         && prv->ratelimit
          && vcpu_runnable(current)
          && !is_idle_vcpu(current)
-         && runtime < MICROSECS(prv->ratelimit_us) )
+         && runtime < prv->ratelimit )
     {
         snext = scurr;
         snext->start_time += now;
         perfc_incr(delay_ms);
         /*
          * Next timeslice must last just until we'll have executed for
-         * ratelimit_us. However, to avoid setting a really short timer, which
+         * ratelimit. However, to avoid setting a really short timer, which
          * will most likely be inaccurate and counterproductive, we never go
          * below CSCHED_MIN_TIMER.
          */
-        tslice = MICROSECS(prv->ratelimit_us) - runtime;
+        tslice = prv->ratelimit - runtime;
         if ( unlikely(runtime < CSCHED_MIN_TIMER) )
             tslice = CSCHED_MIN_TIMER;
         if ( unlikely(tb_init_done) )
@@ -1934,7 +1932,7 @@ csched_schedule(
         ret.migrated = 0;
         goto out;
     }
-    tslice = MILLISECS(prv->tslice_ms);
+    tslice = prv->tslice;
 
     /*
      * Select next runnable local VCPU (ie top of local runq)
@@ -2112,8 +2110,8 @@ csched_dump(const struct scheduler *ops)
            "\tweight             = %u\n"
            "\trunq_sort          = %u\n"
            "\tdefault-weight     = %d\n"
-           "\ttslice             = %dms\n"
-           "\tratelimit          = %dus\n"
+           "\ttslice             = %"PRI_stime"ms\n"
+           "\tratelimit          = %"PRI_stime"us\n"
            "\tcredits per msec   = %d\n"
            "\tticks per tslice   = %d\n"
            "\tmigration delay    = %uus\n",
@@ -2124,8 +2122,8 @@ csched_dump(const struct scheduler *ops)
            prv->weight,
            prv->runq_sort,
            CSCHED_DEFAULT_WEIGHT,
-           prv->tslice_ms,
-           prv->ratelimit_us,
+           prv->tslice / MILLISECS(1),
+           prv->ratelimit / MICROSECS(1),
            CSCHED_CREDITS_PER_MSEC,
            prv->ticks_per_tslice,
            vcpu_migration_delay);
@@ -2206,11 +2204,11 @@ csched_init(struct scheduler *ops)
     {
         printk("WARNING: sched_ratelimit_us >" 
                "sched_credit_tslice_ms is undefined\n"
-               "Setting ratelimit_us to 1000 * tslice_ms\n");
-        prv->ratelimit_us = 1000 * prv->tslice_ms;
+               "Setting ratelimit to tslice\n");
+        prv->ratelimit = prv->tslice;
     }
     else
-        prv->ratelimit_us = sched_ratelimit_us;
+        prv->ratelimit = MICROSECS(sched_ratelimit_us);
     return 0;
 }
 


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