From: Peter Dinda <pdinda@northwestern.edu>
Date: Thu, 18 Jun 2015 21:47:38 +0000 (-0500)
Subject: Subset barrier support (counting barriers)
X-Git-Url: http://v3vee.org/palacios/gitweb/gitweb.cgi?p=palacios.git;a=commitdiff_plain;h=7c0124e75c04de3d51a457f8788cbee61d51fd36

Subset barrier support (counting barriers)
---

diff --git a/palacios/include/palacios/vmm_subset.h b/palacios/include/palacios/vmm_subset.h
new file mode 100644
index 0000000..adc13de
--- /dev/null
+++ b/palacios/include/palacios/vmm_subset.h
@@ -0,0 +1,68 @@
+/*
+ * This file is part of the Palacios Virtual Machine Monitor developed
+ * by the V3VEE Project with funding from the United States National 
+ * Science Foundation and the Department of Energy.  
+ *
+ * The V3VEE Project is a joint project between Northwestern University
+ * and the University of New Mexico.  You can find out more at 
+ * http://www.v3vee.org
+ *
+ * Copyright (c) 2015, Peter Dinda <pdinda@northwestern.edu>
+ * Copyright (c) 2015, The V3VEE Project <http://www.v3vee.org> 
+ * All rights reserved.
+ *
+ * Author: Peter Dinda <pdinda@northwestern.edu>
+ *
+ * This is free software.  You are permitted to use,
+ * redistribute, and modify it as specified in the file "V3VEE_LICENSE".
+ */
+
+#ifndef __VMM_SUBSET_H__
+#define __VMM_SUBSET_H__
+
+#ifdef __V3VEE__
+
+#include <palacios/vmm_types.h>
+
+/* Subset Barriers */
+
+typedef struct v3_counting_barrier {
+    // number of threads that must arrive at the barrier
+    // note that this can only be set when there is no barreir in progress
+    uint64_t      size;
+    uint64_t      count[2];
+    uint64_t      cur;
+} v3_counting_barrier_t;
+
+
+static inline void v3_init_counting_barrier(v3_counting_barrier_t *b, uint64_t size)
+{
+    b->size=size; b->count[0]=b->count[1]=0; b->cur=0;
+}
+
+static inline void v3_counting_barrier(volatile v3_counting_barrier_t *b)
+{
+    uint64_t old;
+    volatile uint64_t *curp = &(b->cur);
+    long mycur = *curp;
+    volatile uint64_t *countp = &(b->count[mycur]);
+ 
+    old = __sync_fetch_and_add(countp,1);
+
+    if (old==(b->size-1)) { 
+	// I'm the last to the party
+	*curp ^= 0x1;
+	*countp = 0;
+    } else {
+	// k1om compiler does not know what "volatile" means
+	// hence this hand-coding.
+	do { 
+	    __asm__ __volatile__( "movq %1, %0" : "=r"(old) : "m"(*countp) : );
+	} while (old);
+    }
+}
+
+
+#endif
+
+#endif