From 5f1c38764d4d23587234740d215342e7daf11f87 Mon Sep 17 00:00:00 2001
From: Jeffrey Altman <jaltman@mit.edu>
Date: Fri, 25 Jun 2004 20:48:44 +0000
Subject: [PATCH] hyperthreading-bad-20040625

Give folks an option of running afsd_service.exe on fewer processors
than are installed in the machine.  A new registry value

	TransarcAfsDaemon/Parameters   MaxCPUs

allows a restriction to be applied.  Set to 1 to use a single CPU
(or hyperthreading instance)

The restriction is applied with SetProcessAffinityMask()
---
 src/WINNT/afsd/afsd_init.c | 37 +++++++++++++++++++++++++++++++++++++
 1 file changed, 37 insertions(+)

diff --git a/src/WINNT/afsd/afsd_init.c b/src/WINNT/afsd/afsd_init.c
index 5da8aceba4..e7bc28a383 100644
--- a/src/WINNT/afsd/afsd_init.c
+++ b/src/WINNT/afsd/afsd_init.c
@@ -205,6 +205,7 @@ int afsd_InitCM(char **reasonP)
 	long logChunkSize;
 	long stats;
 	long traceBufSize;
+    long maxcpus;
 	long ltt, ltto;
     long rx_mtu, rx_nojumbo;
 	char rootCellName[256];
@@ -258,6 +259,42 @@ int afsd_InitCM(char **reasonP)
 		osi_panic(buf, __FILE__, __LINE__);
 	}
 
+    dummyLen = sizeof(maxcpus);
+	code = RegQueryValueEx(parmKey, "MaxCPUs", NULL, NULL,
+				(BYTE *) &maxcpus, &dummyLen);
+	if (code == ERROR_SUCCESS) {
+        HANDLE hProcess;
+        DWORD_PTR processAffinityMask, systemAffinityMask;
+
+        hProcess = OpenProcess(PROCESS_QUERY_INFORMATION|PROCESS_SET_INFORMATION,
+                               FALSE, GetCurrentProcessId());
+        if ( hProcess != NULL &&
+             GetProcessAffinityMask(hProcess, &processAffinityMask, &systemAffinityMask) )
+        {
+            int i, n, bits;
+            DWORD_PTR mask, newAffinityMask;
+
+#if defined(_WIN64)
+            bits = 64;
+#else
+            bits = 32;
+#endif
+            for ( i=0, n=0, mask=1, newAffinityMask=0; i<bits && n<maxcpus; i++ ) {
+                if ( processAffinityMask & mask ) {
+                    newAffinityMask |= mask;
+                    n++;
+                }
+                mask *= 2;
+            }
+
+            SetProcessAffinityMask(hProcess, newAffinityMask);
+            CloseHandle(hProcess);
+            afsi_log("CPU Restrictions set to %d cpu(s); %d cpu(s) available", maxcpus, n);
+        } else {
+            afsi_log("CPU Restrictions set to %d cpu(s); unable to access process information", maxcpus);
+        }
+    }
+
 	dummyLen = sizeof(traceBufSize);
 	code = RegQueryValueEx(parmKey, "TraceBufferSize", NULL, NULL,
 				(BYTE *) &traceBufSize, &dummyLen);