From 5cd3d7557aa7a83eab83ed450dbfbd5f92d2a66e Mon Sep 17 00:00:00 2001
From: Stefan Lankes <lankes@lfbs.rwth-aachen.de>
Date: Sat, 2 Jul 2011 03:13:24 -0700
Subject: [PATCH] fine tuning to increase the performance of the mailbox
 example

---
 arch/x86/include/asm/icc.h  | 10 +++---
 arch/x86/kernel/processor.c |  3 ++
 arch/x86/scc/icc.c          | 61 +++++++++++++++++++------------------
 3 files changed, 38 insertions(+), 36 deletions(-)

diff --git a/arch/x86/include/asm/icc.h b/arch/x86/include/asm/icc.h
index cb806761..9cca3390 100644
--- a/arch/x86/include/asm/icc.h
+++ b/arch/x86/include/asm/icc.h
@@ -39,12 +39,10 @@ typedef struct {
 
 extern bootinfo_t* bootinfo;
 
-/*
-#define ICC_TYPE_IP		(1 << 0)
-#define ICC_TYPE_SVM		(1 << 1)
-#define ICC_TYPE_PINGREQUEST	(1 << 2)
-#define ICC_TYPE_PINGRESPONSE	(1 << 3)
-*/
+#define ICC_TAG_IP		0
+#define ICC_TAG_SVM		1
+#define ICC_TAG_PINGREQUEST	2
+#define ICC_TAG_PINGRESPONSE	3
 
 int icc_init(void);
 int icc_halt(void);
diff --git a/arch/x86/kernel/processor.c b/arch/x86/kernel/processor.c
index 4210c38f..93e5f540 100644
--- a/arch/x86/kernel/processor.c
+++ b/arch/x86/kernel/processor.c
@@ -21,6 +21,7 @@
 #include <metalsvm/stdio.h>
 #include <metalsvm/time.h>
 #include <metalsvm/processor.h>
+#include <metalsvm/tasks.h>
 #ifdef CONFIG_ROCKCREEK
 #include <asm/RCCE_lib.h>
 #endif
@@ -104,6 +105,8 @@ void udelay(uint32_t usecs)
 		mb();
 		end = rdtsc();
 		diff = end > start ? end - start : start - end;
+		if ((diff < deadline) && (deadline - diff > 50000))
+			check_workqueues();
 	} while(diff < deadline);
 }
 
diff --git a/arch/x86/scc/icc.c b/arch/x86/scc/icc.c
index b2a517b9..963eabc3 100644
--- a/arch/x86/scc/icc.c
+++ b/arch/x86/scc/icc.c
@@ -203,27 +203,25 @@ int icc_halt(void)
 		icc_mail_check();
 
 		irq_nested_enable(flags);
+
+		NOP1;
 	} while(do_send);
 
-	HALT;
+	//HALT;
 
 	return 0;
 }
 
 #define MAIL_MSG_SIZE 20
+uint64_t timer;
 
 int icc_mail_ping( void )
 {	
 	uint32_t flags;
-	uint64_t timer;
 	int remote_rank = (my_ue+1)%2;
 
-	char send_buffer[MAIL_MSG_SIZE];
-	int length = MAIL_MSG_SIZE;
-
-	if( my_ue ) {
-		return 0;
-	}
+	if (my_ue)
+		return -1;
 	
 	kprintf( "Hello from mail_ping ... \n" );
 	
@@ -233,25 +231,16 @@ int icc_mail_ping( void )
 	// start timer
 	timer = rdtsc();
 
-	// start anylength send
-	iRCCE_isend( send_buffer, -length, remote_rank, NULL );
+	/* send ping request */
+	iRCCE_mail_send(0, ICC_TAG_PINGREQUEST, 0, NULL, remote_rank);
 
-	// wait for response
-	iRCCE_MAIL_HEADER* mail;
-	do {
-		iRCCE_mail_recv( &mail );
-	} while( !mail );
-	
-	// stop timer
-	timer = rdtsc() - timer;
+	NOP8;
+	icc_send_irq(remote_rank);
 
-	if( mail->tag == 2 ) {
-		kprintf( "Response received in %d ticks!\n", timer );	
-	}
-	else {
-		kprintf( "Response didn't arrive!\n" );
-	}
+	/* check for incoming messages */
+	icc_mail_check();
 
+	// enable interrupts
 	irq_nested_enable(flags);
 
 	return 0;
@@ -261,21 +250,33 @@ void icc_mail_check(void)
 {
 	iRCCE_MAIL_HEADER* header = NULL;
 	int res;
-	char* recv_buffer;
+	//char* recv_buffer;
 
 	// empty mailbox and interpret headers
 	while( 	(res = iRCCE_mail_recv( &header )) == iRCCE_SUCCESS ) {
-		if( header->tag == 1 ) {
-			iRCCE_mail_send( 0, 2, 0, NULL, header->source );	
-		}
-		else if( header->tag == iRCCE_ANYLENGTH ) {
+		switch(header->tag)
+		{
+		case ICC_TAG_PINGREQUEST:
+			iRCCE_mail_send( 0, ICC_TAG_PINGRESPONSE, 0, NULL, header->source );
+			NOP8;
+			icc_send_irq( header->source );
+			break;
+		case ICC_TAG_PINGRESPONSE:
+			timer = rdtsc() - timer;
+			kprintf( "Response received in %d ticks!\n", timer );   
+			break;
+		default:
+			kprintf("Invalid mail: tag = %d\n", header->tag);
+			break;
+		} 
+		/*else if( header->tag == iRCCE_ANYLENGTH ) {
 			recv_buffer = (char*)kmalloc( header->size );
 			iRCCE_irecv( recv_buffer, header->size, header->source, NULL );
 			iRCCE_mail_send( 0, 2, 0, NULL, header->source );	
 		}
 		else if( header->tag == iRCCE_ANYLENGTH_PIGGYBACK ) {
 			iRCCE_mail_send( 0, 2, 0, NULL, header->source );
-		}
+		}*/
 
 		iRCCE_mail_release( &header );
 	}