Date: Sat, 23 Feb 2002 14:43:35 -0800 (PST) From: Matthew Dillon <dillon@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.) Message-ID: <200202232243.g1NMhZP49110@apollo.backplane.com> 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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