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Date:      Fri, 5 May 2006 05:22:52 GMT
From:      Kip Macy <kmacy@FreeBSD.org>
To:        Perforce Change Reviews <perforce@freebsd.org>
Subject:   PERFORCE change 96686 for review
Message-ID:  <200605050522.k455MqpW009676@repoman.freebsd.org>

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http://perforce.freebsd.org/chv.cgi?CH=96686

Change 96686 by kmacy@kmacy_storage:sun4v_rwbuf on 2006/05/05 05:22:22

	switch over to using hash field reference in preparation for handling an arbitrary number of collisions

Affected files ...

.. //depot/projects/kmacy_sun4v/src/sys/sun4v/sun4v/tte_hash.c#19 edit

Differences ...

==== //depot/projects/kmacy_sun4v/src/sys/sun4v/sun4v/tte_hash.c#19 (text+ko) ====

@@ -224,9 +224,15 @@
 	free_tte_hash(th);
 }
 
+static __inline void
+tte_hash_set_field(tte_hash_field_t field, uint64_t tag, tte_t tte)
+{
+	field->tte.tag = tag;
+	field->tte.data = tte | (field->tte.data & VTD_LOCK);
+}
 
 static __inline tte_t 
-tte_hash_lookup_inline(tte_hash_t th, vm_offset_t va, int *index)
+tte_hash_lookup_inline(tte_hash_t th, vm_offset_t va, tte_hash_field_t *field)
 {
 	uint64_t hash_shift, hash_index;
 	tte_hash_field_t fields;
@@ -245,8 +251,8 @@
 			break;
 		}
 	}
-	if (index)
-		*index = i;
+	if (field && i < 4)
+		*field = &fields[i];
         /* 
 	 * XXX handle the case of collisions > 3
 	 */
@@ -258,8 +264,8 @@
 tte_hash_delete(tte_hash_t th, vm_offset_t va)
 {
 	uint64_t hash_shift, hash_index;
-	tte_hash_field_t fields;
-	int i, vaindex, lastindex;
+	tte_hash_field_t fields, lookup_field, last_field;
+	int i;
 	tte_t tte_data;
 	
 	/* XXX - only handle 8K pages for now */
@@ -270,7 +276,7 @@
 
 	hash_bucket_lock(fields);
 	
-	tte_data = tte_hash_lookup_inline(th, va, &vaindex);
+	tte_data = tte_hash_lookup_inline(th, va, &lookup_field);
 
 	if (tte_data == 0)
 		goto done;
@@ -279,16 +285,12 @@
 
 	for (i = 0; (i < 4) && (fields[i + 1].tte.tag != 0); i++) 
 		;
-	lastindex = i;
+	last_field = &fields[i];
 
-	if (vaindex != lastindex) {
-		fields[vaindex].tte.tag = fields[lastindex].tte.tag;
-		fields[vaindex].tte.data = fields[lastindex].tte.data | 
-			(fields[vaindex].tte.data & VTD_LOCK);
-	} 
-	fields[lastindex].tte.tag = 0;
-	fields[lastindex].tte.data = 0 | (fields[lastindex].tte.data & VTD_LOCK);
-
+	if (lookup_field != last_field) 
+		tte_hash_set_field(lookup_field, last_field->tte.tag, last_field->tte.data);
+	
+	tte_hash_set_field(last_field, 0, 0);
 done:	
 	hash_bucket_unlock_inline(fields);
 
@@ -300,8 +302,7 @@
 {
 
 	uint64_t hash_shift, hash_index, tte_tag;
-	tte_hash_field_t fields;
-	int cookie;
+	tte_hash_field_t fields, lookup_field;
 	tte_t otte_data;
 	
 
@@ -313,17 +314,13 @@
 	tte_tag = (((uint64_t)th->th_context << TTARGET_CTX_SHIFT)|(va >> TTARGET_VA_SHIFT));
 
 	hash_bucket_lock(fields);
-	otte_data = tte_hash_lookup_inline(th, va, &cookie);
+	otte_data = tte_hash_lookup_inline(th, va, &lookup_field);
 #ifdef DEBUG
 	if (otte_data)
 		panic("mapping for va=0x%lx already exists tte_data=0x%lx\n", va, otte_data);
 #endif
-	fields[cookie].tte.data = tte_data | (fields[cookie].tte.data & VTD_LOCK);
-	fields[cookie].tte.tag = tte_tag;
-		
-	if (cookie == 3)
-		panic("collision handling unimplemented - please re-consider");
-	
+	tte_hash_set_field(lookup_field, tte_tag, tte_data);
+
 	hash_bucket_unlock_inline(fields);
 	th->th_entries++;
 }
@@ -397,25 +394,25 @@
 tte_hash_update(tte_hash_t th, vm_offset_t va, tte_t tte_data)
 {
 	uint64_t hash_shift, hash_index;
-	tte_hash_field_t fields;
-	int cookie;
+	tte_hash_field_t fields, lookup_field;
 	tte_t otte_data;
-	
+	uint64_t tag;
+
 	/* XXX - only handle 8K pages for now */
 	hash_shift = PAGE_SHIFT;
 	hash_index = (va >> hash_shift) & HASH_MASK(th);
 	fields = (th->th_hashtable[hash_index].the_fields);
 
 	hash_bucket_lock(fields);
-	otte_data = tte_hash_lookup_inline(th, va, &cookie);
+	otte_data = tte_hash_lookup_inline(th, va, &lookup_field);
 #ifdef TTE_DEBUG
 	printf("tte_hash_update(va=0x%lx, tte_data=0x%lx, index=%d)\n", va, tte_data, cookie);
 #endif
-	if (cookie == 3)
-		panic("collision handling unimplemented - please re-consider");
+	
+	tag = (((uint64_t)th->th_context << TTARGET_CTX_SHIFT)|(va >> TTARGET_VA_SHIFT));
+	
+	tte_hash_set_field(lookup_field, tag, tte_data);
 
-	fields[cookie].tte.tag = (((uint64_t)th->th_context << TTARGET_CTX_SHIFT)|(va >> TTARGET_VA_SHIFT));
-	fields[cookie].tte.data = tte_data | (fields[cookie].tte.data & VTD_LOCK);
 	hash_bucket_unlock_inline(fields);
 
 	if (otte_data == 0)



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