Changeset 87819 in vbox

Timestamp:

Feb 20, 2021 10:24:03 AM (4 years ago)

Author:

vboxsync

svn:sync-xref-src-repo-rev:

142880

Message:

VMM: Disabled the EMT yield timer as it is out dated (multi core CPUs) and will be pointless when timers move off the EMTs. bugref:9943

Location:

trunk/src/VBox/VMM

Files:

• VMMR3/VMM.cpp (modified) (11 diffs)
• include/VMMInternal.h (modified) (2 diffs)
• testcase/tstVMStructSize.cpp (modified) (1 diff)

trunk/src/VBox/VMM/VMMR3/VMM.cpp

@@ -205 +205 @@
     pVM->vmm.s.hEvtRendezvousRecursionPopCaller = NIL_RTSEMEVENT;
 
+#if 0 /* pointless when timers doesn't run on EMT */
     /** @cfgm{/YieldEMTInterval, uint32_t, 1, UINT32_MAX, 23, ms}
      * The EMT yield interval.  The EMT yielding is a hack we employ to play a
@@ -212 +213 @@
                                23 /* Value arrived at after experimenting with the grub boot prompt. */);
     AssertMsgRCReturn(rc, ("Configuration error. Failed to query \"YieldEMTInterval\", rc=%Rrc\n", rc), rc);
-
+#endif
 
     /** @cfgm{/VMM/UsePeriodicPreemptionTimers, boolean, true}
@@ -222 +223 @@
      */
     PCFGMNODE pCfgVMM = CFGMR3GetChild(CFGMR3GetRoot(pVM), "VMM");
-    rc = CFGMR3QueryBoolDef(pCfgVMM, "UsePeriodicPreemptionTimers", &pVM->vmm.s.fUsePeriodicPreemptionTimers, true);
+    int rc = CFGMR3QueryBoolDef(pCfgVMM, "UsePeriodicPreemptionTimers", &pVM->vmm.s.fUsePeriodicPreemptionTimers, true);
     AssertMsgRCReturn(rc, ("Configuration error. Failed to query \"VMM/UsePeriodicPreemptionTimers\", rc=%Rrc\n", rc), rc);
 
@@ -657 +658 @@
         case VMINITCOMPLETED_RING3:
         {
+#if 0 /* pointless when timers doesn't run on EMT */
             /*
              * Create the EMT yield timer.
@@ -666 +668 @@
             rc = TMTimerSetMillies(pVM, pVM->vmm.s.hYieldTimer, pVM->vmm.s.cYieldEveryMillies);
             AssertRCReturn(rc, rc);
+#endif
             break;
         }
@@ -995 +998 @@
 VMMR3_INT_DECL(void) VMMR3YieldSuspend(PVM pVM)
 {
+#if 0 /* pointless when timers doesn't run on EMT */
     VMCPU_ASSERT_EMT(pVM->apCpusR3[0]);
     if (!pVM->vmm.s.cYieldResumeMillies)
@@ -1007 +1011 @@
     }
     pVM->vmm.s.u64LastYield = RTTimeNanoTS();
+#else
+    RT_NOREF(pVM);
+#endif
 }
 
@@ -1017 +1024 @@
 VMMR3_INT_DECL(void) VMMR3YieldStop(PVM pVM)
 {
+#if 0 /* pointless when timers doesn't run on EMT */
     if (!pVM->vmm.s.cYieldResumeMillies)
         TMTimerStop(pVM, pVM->vmm.s.hYieldTimer);
     pVM->vmm.s.cYieldResumeMillies = pVM->vmm.s.cYieldEveryMillies;
     pVM->vmm.s.u64LastYield = RTTimeNanoTS();
+#else
+    RT_NOREF(pVM);
+#endif
 }
 
@@ -1031 +1042 @@
 VMMR3_INT_DECL(void) VMMR3YieldResume(PVM pVM)
 {
+#if 0 /* pointless when timers doesn't run on EMT */
     if (pVM->vmm.s.cYieldResumeMillies)
     {
@@ -1036 +1048 @@
         pVM->vmm.s.cYieldResumeMillies = 0;
     }
-}
-
-
+#else
+    RT_NOREF(pVM);
+#endif
+}
+
+
+#if 0 /* pointless when timers doesn't run on EMT */
 /**
  * @callback_method_impl{FNTMTIMERINT, EMT yielder}
@@ -1077 +1093 @@
     TMTimerSetMillies(pVM, hTimer, pVM->vmm.s.cYieldEveryMillies);
 }
+#endif
 
 

trunk/src/VBox/VMM/include/VMMInternal.h

@@ -192 +192 @@
     bool                        afPadding0[7];
 
+#if 0 /* pointless when timers doesn't run on EMT */
     /** The EMT yield timer. */
     TMTIMERHANDLE               hYieldTimer;
@@ -201 +202 @@
     /** The timestamp of the previous yield. (nano) */
     uint64_t                    u64LastYield;
+#endif
 
     /** @name EMT Rendezvous

trunk/src/VBox/VMM/testcase/tstVMStructSize.cpp

@@ -255 +255 @@
     CHECK_MEMBER_ALIGNMENT(VMCPU, vmm.s.CallRing3JmpBufR0.xmm6, 16);
 #endif
-    CHECK_MEMBER_ALIGNMENT(VM, vmm.s.u64LastYield, 8);
 
     /* the VMCPUs are page aligned TLB hit reasons. */