From 4c61e37fca3bd85a813449f019705e002a4e8a50 Mon Sep 17 00:00:00 2001
From: Stefan Lankes <lankes@lfbs.rwth-aachen.de>
Date: Tue, 8 Nov 2011 01:03:27 -0800
Subject: [PATCH] first steps to realize a Lubachevsky barrier with flag

---
 arch/x86/mm/svm.c | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/arch/x86/mm/svm.c b/arch/x86/mm/svm.c
index 3b1afe81..ef29d687 100644
--- a/arch/x86/mm/svm.c
+++ b/arch/x86/mm/svm.c
@@ -37,8 +37,19 @@
 #define SHARED_PAGES		((4*RCCE_SHM_SIZE_MAX) >> PAGE_SHIFT)
 #define OWNER_SIZE		((SHARED_PAGES * sizeof(uint8_t) + PAGE_SIZE - 1) & ~(PAGE_SIZE - 1))
 
+#define AIREG1 0
+#define AIREG2 (AIREG1 + 1)
+
 t_vcharp RC_SHM_BUFFER_START();
 
+typedef struct {
+	int counter;
+	int initializer;
+} atomic_increg_t;
+
+static volatile atomic_increg_t *incregs = NULL;
+static RCCE_FLAG release;
+
 /*
  * This array describes the owner of a specific page.
  * Only the owner of a page is able to change the possession.
@@ -343,12 +354,26 @@ void svm_flush(void)
 
 int svm_barrier(uint32_t type)
 {
+	int i;
+	RCCE_COMM *comm = &RCCE_COMM_WORLD;
+	static int index = 0;
+
 	if (type == SVM_LAZYRELEASE) {
 		svm_flush();
 		svm_invalidate();
 	}
 
+#if 0
+	index = !index;
+	if (incregs[AIREG1].counter > (comm->size - 2)) {
+		incregs[AIREG1].initializer = 0;
+		while(incregs[AIREG1].initializer);
+		for (i = 0; i < comm->size; i++)
+			RCCE_flag_write(&release, index, comm->member[i]);
+	} else RCCE_wait_until(release, index);
+#else
 	RCCE_barrier(&RCCE_COMM_WORLD);
+#endif
 
 	return 0;
 }