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Date: Sat, 23 Feb 2002 14:43:35 -0800 (PST)
From: Matthew Dillon <dillon@apollo.backplane.com>
Message-Id: <200202232243.g1NMhZP49110@apollo.backplane.com>
Cc: Alfred Perlstein <alfred@FreeBSD.ORG>,
	Bosko Milekic <bmilekic@unixdaemons.com>,
	Seigo Tanimura <tanimura@r.dl.itc.u-tokyo.ac.jp>,
	current@FreeBSD.ORG, John Baldwin <jhb@FreeBSD.ORG>
Subject: malloc_bucket() idea (was Re: How to fix malloc.)
References: <200201051752.g05Hq3gG074525@silver.carrots.uucp.r.dl.itc.u-tokyo.ac.jp> <XFMail.020114020307.jhb@FreeBSD.org> <200201241022.g0OAMISM093913@faber.r.dl.itc.u-tokyo.ac.jp> <20020124024534.V13686@elvis.mu.org> <200202131739.g1DHdZT5023794@rina.r.dl.itc.u-tokyo.ac.jp> <200202190945.g1J9j9kg076110@rina.r.dl.itc.u-tokyo.ac.jp> <200202232051.g1NKpE741310@apollo.backplane.com> <20020223211449.GJ80761@elvis.mu.org>  
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    This is approximately what I am thinking.  Note that this gives us the
    flexibility to create a larger infrastructure around the bucket cache,
    such as implement per-cpu caches and so on and so forth.  What I have
    here is the minimal implementation.

						-Matt

Index: kern/kern_malloc.c
===================================================================
RCS file: /home/ncvs/src/sys/kern/kern_malloc.c,v
retrieving revision 1.93
diff -u -r1.93 kern_malloc.c
--- kern/kern_malloc.c	12 Sep 2001 08:37:44 -0000	1.93
+++ kern/kern_malloc.c	23 Feb 2002 22:41:56 -0000
@@ -116,6 +116,63 @@
 #endif /* INVARIANTS */
 
 /*
+ *	init_malloc_bucket:
+ *
+ *	Initialize a malloc bucket
+ */
+void
+init_malloc_bucket(struct malloc_bucket *bucket, struct malloc_type *type, int size)
+{
+    bzero(bucket, sizeof(struct malloc_bucket));
+    bucket->b_size = size;
+    bucket->b_type = type;
+    bucket->b_mtx = mtx_pool_find(bucket);
+}
+
+/*
+ *	malloc_bucket:
+ *
+ *	Allocate a structure from the supplied low-latency cache.  NULL is
+ *	returned if the cache is empty.
+ */
+void *
+malloc_bucket(struct malloc_bucket *bucket)
+{
+	void *ptr = NULL;
+
+	if (bucket->b_next) {
+		mtx_lock(bucket->b_mtx);
+		if ((ptr = bucket->b_next) != NULL) {
+			bucket->b_next = *(caddr_t *)ptr;
+			KASSERT(bucket->b_count > 0, ("bucket count mismatch"));
+			--bucket->b_count;
+			*(caddr_t *)ptr = WEIRD_ADDR;
+		} else {
+			KASSERT(bucket->b_count == 0, ("bucket count mismatch"));
+		}
+		mtx_unlock(bucket->b_mtx);
+	}
+	return(ptr);
+}
+
+/*
+ *	free_bucket:
+ *
+ *	Free a structure to the low latency cache.
+ *
+ */
+void
+free_bucket(struct malloc_bucket *bucket, void *ptr)
+{
+	mtx_lock(bucket->b_mtx);
+	*(caddr_t *)ptr = bucket->b_next;
+	bucket->b_next = (caddr_t)ptr;
+	++bucket->b_count;
+	mtx_unlock(bucket->b_mtx);
+	/* XXX if b_count > something, wakeup our cleaner? */
+}
+
+/*
  *	malloc:
  *
  *	Allocate a block of memory.
Index: sys/malloc.h
===================================================================
RCS file: /home/ncvs/src/sys/sys/malloc.h,v
retrieving revision 1.54
diff -u -r1.54 malloc.h
--- sys/malloc.h	10 Aug 2001 06:37:04 -0000	1.54
+++ sys/malloc.h	23 Feb 2002 22:36:09 -0000
@@ -109,6 +109,18 @@
 	long	kb_couldfree;	/* over high water mark and could free */
 };
 
+/*
+ * malloc_bucket holder for fast low-latency malloc_bucket() and free_bucket()
+ * calls.
+ */
+struct malloc_bucket {
+	caddr_t b_next;
+	int	b_count;
+	int	b_size;
+	struct mtx *b_mtx;
+	struct malloc_type *b_type;
+};
+
 #ifdef _KERNEL
 #define	MINALLOCSIZE	(1 << MINBUCKET)
 #define BUCKETINDX(size) \

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