From 4c2525c0b36200139ee7ad3f957cf285a0b23de6 Mon Sep 17 00:00:00 2001
From: Stefan Lankes <lankes@lfbs.rwth-aachen.de>
Date: Mon, 7 Nov 2011 11:28:44 -0800
Subject: [PATCH] add code to evaluate the performance of our SVM system

---
 arch/x86/mm/svm.c | 61 ++++++++++++++++++++++++++++++++++-------------
 1 file changed, 44 insertions(+), 17 deletions(-)

diff --git a/arch/x86/mm/svm.c b/arch/x86/mm/svm.c
index 6a0449b2..a1085287 100644
--- a/arch/x86/mm/svm.c
+++ b/arch/x86/mm/svm.c
@@ -34,7 +34,7 @@
 #include <asm/icc.h>
 #include <asm/svm.h>
 
-#define SHARED_PAGES		(RCCE_SHM_SIZE_MAX >> PAGE_SHIFT)
+#define SHARED_PAGES		((4*RCCE_SHM_SIZE_MAX) >> PAGE_SHIFT)
 #define OWNER_SIZE		((SHARED_PAGES * sizeof(uint8_t) + PAGE_SIZE - 1) & ~(PAGE_SIZE - 1))
 
 t_vcharp RC_SHM_BUFFER_START();
@@ -52,6 +52,11 @@ static size_t shmbegin = 0;
 static uint32_t emit[RCCE_MAXNP] = {[0 ... RCCE_MAXNP-1] = 0};
 static uint32_t request[RCCE_MAXNP] = {[0 ... RCCE_MAXNP-1] = 0};
 static uint32_t forward[RCCE_MAXNP] = {[0 ... RCCE_MAXNP-1] = 0};
+static uint64_t request_ticks = 0;
+static uint64_t emit_ticks = 0;
+static uint64_t wait_ticks = 0;
+static uint64_t max_wait = 0;
+static uint64_t min_wait = (uint64_t) -1;
 
 int svm_init(void)
 {
@@ -99,10 +104,12 @@ int svm_init(void)
  */
 int svm_access_request(size_t addr)
 {
+	uint64_t start = rdtsc();
 	size_t phyaddr = virt_to_phys(addr);
 	uint32_t pageid;
 	int remote_rank;
 	uint8_t payload[iRCCE_MAIL_HEADER_PAYLOAD];
+	int ret;
 
 	if (phyaddr < shmbegin)
 		return -EINVAL;
@@ -110,25 +117,33 @@ int svm_access_request(size_t addr)
 		return -EINVAL;
 	pageid = (phyaddr-shmbegin) >> PAGE_SHIFT;
 
-	if (page_owner[pageid] == RCCE_IAM)
+	remote_rank = page_owner[pageid];
+	if (remote_rank == RCCE_IAM)
 		return 0;
 
-	remote_rank = page_owner[pageid];
 	((size_t*) payload)[0] = RCCE_IAM;
 	((size_t*) payload)[1] = phyaddr;
 
 	/* send ping request */
 	iRCCE_mail_send(2*sizeof(size_t), SVM_REQUEST, 0, payload, remote_rank);
-
+	icc_send_gic_irq(remote_rank);	
 	request[remote_rank]++;
-	icc_send_gic_irq(remote_rank);
 
-	while (page_owner[pageid] != RCCE_IAM) {
-		icc_mail_check();
-		NOP8;
-	}
+	uint64_t wait_start = rdtsc();
+	// wait for response
+	icc_wait(SVM_RESP);
+	uint64_t res = rdtsc() - wait_start;
+	wait_ticks += res;
+	if (min_wait > res)
+		min_wait = res;
+	if (max_wait < res)
+		max_wait = res;
 
-	return change_page_permissions(addr, addr+PAGE_SIZE, VMA_READ|VMA_WRITE|VMA_CACHEABLE);
+	ret = change_page_permissions(addr, addr+PAGE_SIZE, VMA_READ|VMA_WRITE|VMA_CACHEABLE);
+
+	request_ticks += rdtsc() - start;
+
+	return ret;
 }
 
 static atomic_int32_t size_counter = ATOMIC_INIT(0);
@@ -148,7 +163,7 @@ void* svmmalloc(size_t size, uint32_t consistency)
 	// currently, we allocate memory in page size granulation
 	size = (size + PAGE_SIZE - 1) & ~(PAGE_SIZE - 1);
 
-#if 0 	// Workaround for our MARC paper
+#if 1 	// Workaround for our MARC paper
 	// iRCCE is not thread save => disable interrupts
 	flags = irq_nested_disable();
 
@@ -253,8 +268,10 @@ void svmfree(void* addr, size_t size)
  * => Interrupt flag is alread cleared.
  */
 int svm_emit_page(size_t phyaddr, int ue)
-{	
+{
+	uint64_t start = rdtsc();	
 	uint32_t pageid;
+	int remote_rank;
 
 	//kprintf("Try to emit page 0x%x to %d\n", phyaddr, ue);
 
@@ -264,14 +281,13 @@ int svm_emit_page(size_t phyaddr, int ue)
 		return -EINVAL;
 	pageid = (phyaddr-shmbegin) >> PAGE_SHIFT;
 
-	if (page_owner[pageid] != RCCE_IAM) {
+	remote_rank = page_owner[pageid];	
+	if (remote_rank != RCCE_IAM) {
 		// Core is nor owner => forward request to new owner
-		int remote_rank;
 		uint8_t payload[iRCCE_MAIL_HEADER_PAYLOAD];
 
 		kprintf("Ups, core %d is not owner of page 0x%x\n", RCCE_IAM, phyaddr);
 
-		remote_rank = page_owner[pageid];
 		((size_t*) payload)[0] = ue;
 		((size_t*) payload)[1] = phyaddr;
 
@@ -285,13 +301,19 @@ int svm_emit_page(size_t phyaddr, int ue)
 		size_t viraddr;
 
 		svm_flush();
-		page_owner[pageid] = ue;
+
+		// send response back to ue
+		// ue is polling for the response => no irq is needed
+		iRCCE_mail_send(0, SVM_RESP, 0, NULL, ue);
 
 		emit[ue]++;
-		viraddr = phys2virt[(phyaddr - shmbegin) >> PAGE_SHIFT];
+		viraddr = phys2virt[pageid];
+		page_owner[pageid] = ue;
 		change_page_permissions(viraddr, viraddr+PAGE_SIZE, VMA_NOACCESS|VMA_READ|VMA_CACHEABLE);
 	}
 
+	emit_ticks += rdtsc() - start;
+
 	return 0;
 }
 
@@ -333,6 +355,11 @@ int svm_statistics(void)
 	for(i=0; i<RCCE_MAXNP; i++)
 		kprintf("\t%u", forward[i]);
 	kputs("\n");
+	kprintf("request ticks: %llu\n", request_ticks);
+	kprintf("wait ticks: %llu\n", wait_ticks);
+	kprintf("emit ticks: %llu\n", emit_ticks);
+	kprintf("max wait: %llu\n", max_wait);
+	kprintf("min wait: %llu\n", min_wait);
 
 	return 0;
 }