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Date:      Wed, 5 Dec 2012 18:29:00 GMT
From:      Brooks Davis <brooks@FreeBSD.org>
To:        Perforce Change Reviews <perforce@freebsd.org>
Subject:   PERFORCE change 219886 for review
Message-ID:  <201212051829.qB5IT0Vb078243@skunkworks.freebsd.org>
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http://p4web.freebsd.org/@@219886?ac=10

Change 219886 by brooks@brooks_zenith on 2012/12/05 18:28:12

	Improve the stub malloc to allocated 32-byte aligned chunks with
	size data and red zone padding in front of each allocation.  ~1%
	performance improvement.
	
	Don't verify the readzones for now.  It's slower and there's a bug
	I've not yet tracked down in the case of files smaller than a page.

Affected files ...

.. //depot/projects/ctsrd/cheribsd/src/ctsrd/minifile/cheri/malloc.c#2 edit

Differences ...

==== //depot/projects/ctsrd/cheribsd/src/ctsrd/minifile/cheri/malloc.c#2 (text+ko) ====

@@ -34,6 +34,19 @@
 #include <stdlib.h>
 #include <string.h>
 
+#define CTASSERT(x)     _Static_assert(x, "compile-time assertion failed");
+
+static const uint64_t red0 = 0x0123456789ABCDEF;
+static const uint64_t red1 = 0xFEDCBA9876543210;
+
+struct minfo {
+	uint64_t	red0;
+	size_t		size;
+	size_t		rsize;
+	uint64_t	red1;
+};
+CTASSERT(sizeof(struct minfo) == 32);
+
 void	*_sb_heapbase;
 size_t	 _sb_heaplen;
 
@@ -41,13 +54,22 @@
 malloc(size_t size)
 {
 	size_t rsize;
+	struct minfo *minfo;
 	char *ptr;
 
-	rsize = roundup2(size, 4096);
-	if (_sb_heaplen < rsize)
+	rsize = roundup2(size, sizeof(minfo));
+	if (_sb_heaplen < rsize + sizeof(minfo))
 		return (NULL);
 
-	ptr = _sb_heapbase;
+	minfo = _sb_heapbase;
+	*minfo = (struct minfo) {
+		.red0 = red0,
+		.size = size,
+		.rsize = rsize,
+		.red1 = red1
+	};
+	_sb_heaplen -= sizeof(minfo);
+	ptr = (char *)(minfo + 1);
 	_sb_heaplen -= rsize;
 	_sb_heapbase = ptr + rsize;
 
@@ -67,22 +89,42 @@
 }
 
 void
-free(void *ptr __unused)
+free(void *ptr)
 {
+#ifdef CHECK_RZ
+	struct minfo *minfo;
 
+	minfo = ptr;
+	minfo--;
+	if (minfo->red0 != red0 || minfo->red1 != red1)
+		abort();
+#endif
 }
 
 void *
 realloc(void *ptr, size_t size)
 {
 	char *nptr;
+	struct minfo *minfo;
+
+	if (ptr == NULL)
+		return (malloc(size));
+
+	minfo = ptr;
+	minfo--;
+#ifdef CHECK_RZ
+	if (minfo->red0 != red0 || minfo->red1 != red1)
+		abort();
+#endif
 	
-	if (size <= 4096 && ptr != NULL)
+	if (size <= minfo->rsize) {
+		minfo->size = size;
 		return (ptr);
+	}
 	
 	nptr = malloc(size);
-	if (nptr != NULL && ptr != NULL) {
-		memcpy(nptr, ptr, MIN(size, (size_t)nptr - (size_t)ptr));
+	if (nptr != NULL) {
+		memcpy(nptr, ptr, minfo->size);
 		free(ptr);
 	}

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