[Xen-changelog] [xen-3.0-testing] [SEDF] Fix SEDF defaults to make domain0 take only a fair

[Xen patchbot-3.0-testing <patchbot-3.0-testing@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User kaf24@xxxxxxxxxxxxxxxxxxxx
# Node ID fb7f7f3e2909b799dca1f5c839c2c0e75d19b455
# Parent  265866baa61fe0b613f35ed6fbddf05fad8a8f6a
[SEDF] Fix SEDF defaults to make domain0 take only a fair
equally-weighted share of extratime. Also, hack the short-
blocking logic as otherwise domain0 steals all CPU time 
for several seconds after waking from a long sleep.
Signed-off-by: Keir Fraser <keir@xxxxxxxxxxxxx>
xen-unstable changeset:   10438:ef8cdd1dc8360e310423a599ff1da76fb111bc96
xen-unstable date:        Sat Jun 17 11:29:35 2006 +0100
---
 xen/common/sched_sedf.c |   31 ++++++++++++++++++++-----------
 1 files changed, 20 insertions(+), 11 deletions(-)

diff -r 265866baa61f -r fb7f7f3e2909 xen/common/sched_sedf.c
--- a/xen/common/sched_sedf.c   Mon Jun 19 15:12:13 2006 +0100
+++ b/xen/common/sched_sedf.c   Mon Jun 19 15:20:08 2006 +0100
@@ -374,25 +374,24 @@ static void sedf_add_task(struct vcpu *d
         INIT_LIST_HEAD(EXTRAQ(d->processor,EXTRA_PEN_Q));
         INIT_LIST_HEAD(EXTRAQ(d->processor,EXTRA_UTIL_Q));
     }
-       
+
+    /* Every VCPU gets an equal share of extratime by default. */
+    inf->deadl_abs   = 0;
+    inf->latency     = 0;
+    inf->status      = EXTRA_AWARE | SEDF_ASLEEP;
+    inf->extraweight = 1;
+
     if ( d->domain->domain_id == 0 )
     {
-        /*set dom0 to something useful to boot the machine*/
+        /* Domain0 gets 75% guaranteed (15ms every 20ms). */
         inf->period    = MILLISECS(20);
         inf->slice     = MILLISECS(15);
-        inf->latency   = 0;
-        inf->deadl_abs = 0;
-        inf->status     = EXTRA_AWARE | SEDF_ASLEEP;
     }
     else
     {
-        /*other domains run in best effort mode*/
+        /* Best-effort extratime only. */
         inf->period    = WEIGHT_PERIOD;
         inf->slice     = 0;
-        inf->deadl_abs = 0;
-        inf->latency   = 0;
-        inf->status     = EXTRA_AWARE | SEDF_ASLEEP;
-        inf->extraweight = 1;
     }
 
     inf->period_orig = inf->period; inf->slice_orig = inf->slice;
@@ -640,7 +639,17 @@ static void desched_extra_dom(s_time_t n
         PRINT(3,"Domain %i.%i: Short_block_loss: %"PRIi64"\n", 
               inf->vcpu->domain->domain_id, inf->vcpu->vcpu_id,
               inf->short_block_lost_tot);
-        if (inf->short_block_lost_tot <= 0) {
+#if 0
+        /*
+         * KAF: If we don't exit short-blocking state at this point
+         * domain0 can steal all CPU for up to 10 seconds before
+         * scheduling settles down (when competing against another
+         * CPU-bound domain). Doing this seems to make things behave
+         * nicely. Noone gets starved by default.
+         */
+        if (inf->short_block_lost_tot <= 0)
+#endif
+        {
             PRINT(4,"Domain %i.%i compensated short block loss!\n",
                   inf->vcpu->domain->domain_id, inf->vcpu->vcpu_id);
             /*we have (over-)compensated our block penalty*/

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