[Xen-devel] [PATCH v3 4/7] xen/tools: tracing: add record for credit1 runqueue stealing.

[Dario Faggioli <dario.faggioli@xxxxxxxxxx>]

Including whether we actually tried stealing a vCPU from
a given pCPU, or we skipped that one, because of lock
contention.

Signed-off-by: Dario Faggioli <dario.faggioli@xxxxxxxxxx>
Acked-by: George Dunlap <george.dunlap@xxxxxxxxxx>
---
Cc: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
Cc: Wei Liu <wei.liu2@xxxxxxxxxx>
---
Changes from v2:
* make the code less cool! :-( (i.e., change "skipp'n" to just "skip" in a
  comment.)
---
 tools/xentrace/formats       |    1 +
 tools/xentrace/xenalyze.c    |   11 +++++++++++
 xen/common/sched_credit.c    |    6 +++++-
 xen/include/xen/perfc_defn.h |    1 +
 4 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/tools/xentrace/formats b/tools/xentrace/formats
index a055231..8b31780 100644
--- a/tools/xentrace/formats
+++ b/tools/xentrace/formats
@@ -47,6 +47,7 @@
 0x00022008  CPU%(cpu)d  %(tsc)d (+%(reltsc)8d)  csched:unboost       [ 
dom:vcpu = 0x%(1)04x%(2)04x ]
 0x00022009  CPU%(cpu)d  %(tsc)d (+%(reltsc)8d)  csched:schedule      [ 
cpu[16]:tasklet[8]:idle[8] = %(1)08x ]
 0x0002200A  CPU%(cpu)d  %(tsc)d (+%(reltsc)8d)  csched:ratelimit     [ 
dom:vcpu = 0x%(1)08x, runtime = %(2)d ]
+0x0002200B  CPU%(cpu)d  %(tsc)d (+%(reltsc)8d)  csched:steal_check   [ 
peer_cpu = %(1)d, checked = %(2)d ]
 
 0x00022201  CPU%(cpu)d  %(tsc)d (+%(reltsc)8d)  csched2:tick
 0x00022202  CPU%(cpu)d  %(tsc)d (+%(reltsc)8d)  csched2:runq_pos       [ 
dom:vcpu = 0x%(1)08x, pos = %(2)d]
diff --git a/tools/xentrace/xenalyze.c b/tools/xentrace/xenalyze.c
index 029c89d..fa608ad 100644
--- a/tools/xentrace/xenalyze.c
+++ b/tools/xentrace/xenalyze.c
@@ -7651,6 +7651,17 @@ void sched_process(struct pcpu_info *p)
                        r->runtime / 1000, r->runtime % 1000);
             }
             break;
+        case TRC_SCHED_CLASS_EVT(CSCHED, 11): /* STEAL_CHECK   */
+            if(opt.dump_all) {
+                struct {
+                    unsigned int peer_cpu, check;
+                } *r = (typeof(r))ri->d;
+
+                printf(" %s csched:load_balance %s %u\n",
+                       ri->dump_header, r->check ? "checking" : "skipping",
+                       r->peer_cpu);
+            }
+            break;
         /* CREDIT 2 (TRC_CSCHED2_xxx) */
         case TRC_SCHED_CLASS_EVT(CSCHED2, 1): /* TICK              */
         case TRC_SCHED_CLASS_EVT(CSCHED2, 4): /* CREDIT_ADD        */
diff --git a/xen/common/sched_credit.c b/xen/common/sched_credit.c
index 7b4ea02..59b87f7 100644
--- a/xen/common/sched_credit.c
+++ b/xen/common/sched_credit.c
@@ -134,6 +134,7 @@
 #define TRC_CSCHED_BOOST_END     TRC_SCHED_CLASS_EVT(CSCHED, 8)
 #define TRC_CSCHED_SCHEDULE      TRC_SCHED_CLASS_EVT(CSCHED, 9)
 #define TRC_CSCHED_RATELIMIT     TRC_SCHED_CLASS_EVT(CSCHED, 10)
+#define TRC_CSCHED_STEAL_CHECK   TRC_SCHED_CLASS_EVT(CSCHED, 11)
 
 
 /*
@@ -1753,14 +1754,17 @@ csched_load_balance(struct csched_private *prv, int cpu,
                  * balancing and trying to lock this CPU.
                  */
                 spinlock_t *lock = pcpu_schedule_trylock(peer_cpu);
-
+                SCHED_STAT_CRANK(steal_trylock);
                 if ( !lock )
                 {
                     SCHED_STAT_CRANK(steal_trylock_failed);
+                    TRACE_2D(TRC_CSCHED_STEAL_CHECK, peer_cpu, /* skip */ 0);
                     peer_cpu = cpumask_cycle(peer_cpu, &workers);
                     continue;
                 }
 
+                TRACE_2D(TRC_CSCHED_STEAL_CHECK, peer_cpu, /* checked */ 1);
+
                 /* Any work over there to steal? */
                 speer = cpumask_test_cpu(peer_cpu, online) ?
                     csched_runq_steal(peer_cpu, cpu, snext->pri, bstep) : NULL;
diff --git a/xen/include/xen/perfc_defn.h b/xen/include/xen/perfc_defn.h
index 0d702f0..53849af 100644
--- a/xen/include/xen/perfc_defn.h
+++ b/xen/include/xen/perfc_defn.h
@@ -48,6 +48,7 @@ PERFCOUNTER(vcpu_unpark,            "csched: vcpu_unpark")
 PERFCOUNTER(load_balance_idle,      "csched: load_balance_idle")
 PERFCOUNTER(load_balance_over,      "csched: load_balance_over")
 PERFCOUNTER(load_balance_other,     "csched: load_balance_other")
+PERFCOUNTER(steal_trylock,          "csched: steal_trylock")
 PERFCOUNTER(steal_trylock_failed,   "csched: steal_trylock_failed")
 PERFCOUNTER(steal_peer_idle,        "csched: steal_peer_idle")
 PERFCOUNTER(migrate_queued,         "csched: migrate_queued")


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