diff --git a/checkin_notes b/checkin_notes
index 11183f69aa..212f0660f1 100644
--- a/checkin_notes
+++ b/checkin_notes
@@ -277,3 +277,16 @@ Rom    7 Jan 2012
     samples/vboxwrapper/
         vbox.cpp, .h
         vboxwrapper.cpp, .h
+
+David  7 Jan 2012
+    - scheduler: change vbox_mt app plan function to use 1, 2 or 3 CPUs
+        depending on how many the host has,
+        and whether CPU VM extensions are present
+        (this reflects the requirements of CernVM).
+
+    db/
+        boinc_db.h
+    sched/
+        sched_types.h
+        sched_customize.cpp
+        validator.cpp
diff --git a/db/boinc_db.h b/db/boinc_db.h
index 5bbb8bdd66..efa5f32161 100644
--- a/db/boinc_db.h
+++ b/db/boinc_db.h
@@ -548,9 +548,7 @@ struct RESULT {
     double elapsed_time;
         // AKA runtime; returned by 6.10+ clients
     double flops_estimate;
-        // misnomer: actually the peak device FLOPS,
-        // returned by app_plan()
-        // An adjusted version of this is sent to clients.
+        // misnomer: actually the peak device FLOPS, returned by app_plan().
     int app_version_id;
         // ID of app version used to compute this
         // 0 if unknown (relic of old scheduler)
diff --git a/sched/sched_customize.cpp b/sched/sched_customize.cpp
index 287ec1d9be..6996ac2eea 100644
--- a/sched/sched_customize.cpp
+++ b/sched/sched_customize.cpp
@@ -514,9 +514,15 @@ static inline bool app_plan_opencl(
     }
 }
 
+// handles vbox_[32|64][_mt]
+// "mt" is tailored to the needs of CERN:
+// use 1, 2 or 3 CPUs
+
 static inline bool app_plan_vbox(
     SCHEDULER_REQUEST& sreq, char* plan_class, HOST_USAGE& hu
 ) {
+    bool can_use_multicore = true;
+
     // host must have VirtualBox 3.2 or later
     //
     if (strlen(sreq.host.virtualbox_version) == 0) return false;
@@ -528,14 +534,12 @@ static inline bool app_plan_vbox(
 
     // host must have VM acceleration in order to run multi-core jobs
     //
-    if (strstr(plan_class, "mt") 
-        && (!strstr(sreq.host.p_features, "vmx")
-        && !strstr(sreq.host.p_features, "svm"))
-    ) {
-        return false;
-    }
-    if (strstr(plan_class, "mt") && sreq.host.p_vm_extensions_disabled) {
-        return false;
+    if (strstr(plan_class, "mt")) {
+        if ((!strstr(sreq.host.p_features, "vmx") && !strstr(sreq.host.p_features, "svm"))
+            || sreq.host.p_vm_extensions_disabled
+        ) {
+            can_use_multicore = false;
+        }
     }
 
     // only send the version for host's primary platform.
@@ -549,12 +553,11 @@ static inline bool app_plan_vbox(
         if (strstr(plan_class, "64")) return false;
     }
 
-    if (strstr(plan_class, "mt")) {
+    if (strstr(plan_class, "mt") && can_use_multicore) {
         double ncpus = g_wreq->effective_ncpus;
             // number of usable CPUs, taking user prefs into account
-        if (ncpus < 2) return false;
         int nthreads = (int)ncpus;
-        if (nthreads > 2) nthreads = 2;
+        if (nthreads > 3) nthreads = 3;
         hu.avg_ncpus = nthreads;
         sprintf(hu.cmdline, "--nthreads %d", nthreads);
     } else {
diff --git a/sched/sched_types.h b/sched/sched_types.h
index bf00bac471..68822801f3 100644
--- a/sched/sched_types.h
+++ b/sched/sched_types.h
@@ -84,15 +84,15 @@ struct HOST_USAGE {
         peak_flops = 0;
         strcpy(cmdline, "");
     }
-    void sequential_app(double x) {
+    void sequential_app(double flops) {
         ncudas = 0;
         natis = 0;
         gpu_ram = 0;
         avg_ncpus = 1;
         max_ncpus = 1;
-        if (x <= 0) x = 1e9;
-        projected_flops = x;
-        peak_flops = x;
+        if (flops <= 0) flops = 1e9;
+        projected_flops = flops;
+        peak_flops = flops;
         strcpy(cmdline, "");
     }
     inline bool is_sequential_app() {
diff --git a/sched/validator.cpp b/sched/validator.cpp
index a4cb2e043b..310052400f 100644
--- a/sched/validator.cpp
+++ b/sched/validator.cpp
@@ -413,6 +413,11 @@ int handle_wu(
                                 runtime = max_runtime;
                             }
                             credit = result.flops_estimate * runtime * COBBLESTONE_SCALE;
+                            log_messages.printf(MSG_NORMAL,
+                                "[WU#%d][RESULT#%d] credit_from_runtime %.2f = %.0fs * %.2fGFLOPS\n",
+                                wu.id, result.id,
+                                credit, runtime, result.flops_estimate/1e9
+                            );
                             break;
                         }
                     }
@@ -688,6 +693,7 @@ int main(int argc, char** argv) {
       "  --max_granted_credit X  Grant no more than this amount of credit to a result\n"
       "  --update_credited_job   Add record to credited_job table after granting credit\n"
       "  --credit_from_wu        Credit is specified in WU XML\n"
+      "  --credit_from_runtime X  Grant credit based on runtime (max X seconds)and estimated FLOPS\n"
       "  --no_credit             Don't grant credit\n"
       "  --sleep_interval n      Set sleep-interval to n\n"
       "  -d n, --debug_level n   Set log verbosity level, 1-4\n"