This patch implements a scalable bitmask specifically
for tracking CPUs. It consists of two architecture-independent
files, cpumap.h and cpumap.c. These files add a new datatype and
supporting functions which allow for future expansion to a CPU count
which is not confined to the bit-size of (unsigned long). The new
datatype (cpumap_t) and supporting interfaces are optimized at
compile-time according to the definition of NR_CPUS.
These interfaces provide a path for gradual code migration to
prepare for the support of systems with larger than 32 processors.
One of the primary goals is to provide current functionality without
affecting performance. The following is a list of bitmasks that could
be converted to the new datatype.
cpu_initialized
wait_init_idle
cpu_online_map/cpu_present_mask
cpu_callin_map
cpu_callout_map
NOTE: The cpumap_to_ulong() and cpumap_ulong_to_cpumap() interfaces
are provided specifically for migration. If these interfaces are
used when NR_CPUS is greater than the bitsize of (unsigned long),
they will cause a link-time failure.
diff -Nru a/include/linux/cpumap.h b/include/linux/cpumap.h
--- /dev/null Wed Dec 31 16:00:00 1969
+++ b/include/linux/cpumap.h Wed Jul 10 11:23:30 2002
@@ -0,0 +1,110 @@
+/*
+ * cpumap_t data type and supporting functions
+ *
+ * Copyright (c) 2002 IBM Corp.
+ *
+ * 01/25/02 Initial Version Russ Weight <[email protected]>
+ * 03/20/02 Move larger functions to cpumap.c Russ Weight
+ *
+ * All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or (at
+ * your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
+ * NON INFRINGEMENT. See the GNU General Public License for more
+ * details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ *
+ */
+#ifndef __LINUX_CPUMAP_H
+#define __LINUX_CPUMAP_H
+
+#include <linux/config.h>
+#include <linux/threads.h>
+#include <asm/types.h>
+
+#define CPUMAP_SIZE ((NR_CPUS + BITS_PER_LONG - 1) / BITS_PER_LONG)
+
+#ifndef __ASSEMBLY__
+#include <linux/bitops.h>
+typedef unsigned long cpumap_t[CPUMAP_SIZE];
+
+/*
+ * The following interfaces are the same regardless of CPUMAP_SIZE
+ */
+#define cpumap_clear_bit clear_bit
+#define cpumap_set_bit set_bit
+#define cpumap_test_and_set_bit test_and_set_bit
+#define cpumap_test_bit test_bit
+
+#if (NR_CPUS % BITS_PER_LONG)
+#define CPUMAP_FILLMASK ((1 << (NR_CPUS % BITS_PER_LONG)) -1)
+#else
+#define CPUMAP_FILLMASK (~0UL)
+#endif
+
+/*
+ * The following macros and prototype are used to format
+ * a cpumap_t object for display. This function knows the
+ * minimum size required, which is provided as CPUMAP_BUFSIZE.
+ *
+ * The CPUMAP_BUFSIZE is an exact calcuation of the byte count
+ * required to display a cpumap_t object.
+ */
+
+#define CPUMAP_BUFSIZE (((sizeof(long) * 2) + 1) * CPUMAP_SIZE + 2)
+
+#if BITS_PER_LONG > 32
+#define CPUMAP_FORMAT_STR "%016lx"
+#else
+#define CPUMAP_FORMAT_STR "%08lx"
+#endif
+extern char *cpumap_format(cpumap_t map, char *buf, int size);
+
+#if CPUMAP_SIZE == 1
+/*
+ * The following interfaces are optimized for the case where
+ * CPUMAP_SIZE==1 (i.e. a single unsigned long). The single
+ * CPU case falls into the CPUMAP_SIZE==1 case.
+ */
+#define cpumap_to_ulong(cpumap) (cpumap[0])
+#define cpumap_ulong_to_cpumap(bitmap, cpumap) (cpumap[0] = bitmap)
+#define cpumap_is_empty(cpumap) (cpumap[0] == 0)
+#define cpumap_cmp_mask(map1, map2) (map1[0] == map2[0])
+#define cpumap_clear_mask(cpumap) (cpumap[0] = 0)
+#define cpumap_fill(cpumap) (cpumap[0] = CPUMAP_FILLMASK)
+#define cpumap_copy_mask(srcmap, destmap) (destmap[0] = srcmap[0])
+#define cpumap_and_mask(map1, map2, result) (result[0] = map1[0] & map2[0])
+
+#else
+
+/*
+ * The cpumap_to_ulong() and cpumap_ulong_to_cpumap() functions
+ * are provided to facilitate migration to the cpumap_t datatype.
+ * As currently defined, they are only valid for CPUMAP_SIZE==1.
+ * If they are referenced when CPUMAP_SIZE > 1, then we call a
+ * bogus function name in order to trigger a link-time error.
+ */
+extern unsigned long __bad_cpumap_to_ulong(void);
+extern void __bad_cpumap_ulong_to_cpumap(void);
+#define cpumap_to_ulong(cpumap) __bad_cpumap_to_ulong()
+#define cpumap_ulong_to_cpumap(bitmap, cpumap) __bad_cpumap_ulong_to_cpumap()
+
+extern int cpumap_is_empty(cpumap_t map);
+extern int cpumap_cmp_mask(cpumap_t map1, cpumap_t map2);
+extern void cpumap_clear_mask(cpumap_t cpumap);
+extern void cpumap_fill(cpumap_t cpumap);
+extern void cpumap_copy_mask(cpumap_t srcmap, cpumap_t destmap);
+extern void cpumap_and_mask(cpumap_t map1, cpumap_t map2, cpumap_t result);
+
+#endif
+#endif
+#endif
diff -Nru a/lib/Makefile b/lib/Makefile
--- a/lib/Makefile Wed Jul 10 11:23:30 2002
+++ b/lib/Makefile Wed Jul 10 11:23:30 2002
@@ -9,10 +9,10 @@
L_TARGET := lib.a
export-objs := cmdline.o dec_and_lock.o rwsem-spinlock.o rwsem.o \
- crc32.o rbtree.o radix-tree.o
+ crc32.o rbtree.o radix-tree.o cpumap.o
obj-y := errno.o ctype.o string.o vsprintf.o brlock.o cmdline.o \
- bust_spinlocks.o rbtree.o radix-tree.o
+ bust_spinlocks.o rbtree.o radix-tree.o cpumap.o
obj-$(CONFIG_RWSEM_GENERIC_SPINLOCK) += rwsem-spinlock.o
obj-$(CONFIG_RWSEM_XCHGADD_ALGORITHM) += rwsem.o
diff -Nru a/lib/cpumap.c b/lib/cpumap.c
--- /dev/null Wed Dec 31 16:00:00 1969
+++ b/lib/cpumap.c Wed Jul 10 11:23:30 2002
@@ -0,0 +1,132 @@
+/*
+ * Supporting functions for cpumap_t data type
+ *
+ * Copyright (c) 2002 IBM Corp.
+ *
+ * 03/20/02 Initial Version Russ Weight <[email protected]>
+ *
+ * All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or (at
+ * your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
+ * NON INFRINGEMENT. See the GNU General Public License for more
+ * details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ *
+ */
+#include <linux/kernel.h>
+#include <linux/cpumap.h>
+#include <asm/string.h>
+
+/* Not all architectures define BUG() */
+#ifndef BUG
+ #define BUG() do { \
+ printk("kernel BUG at %s:%d!\n", __FILE__, __LINE__); \
+ * ((char *) 0) = 0; \
+ } while (0)
+#endif /* BUG */
+
+/*
+ * The cpumap_format() function is used to format a cpumap_t
+ * object for display. This function knows the minimum size
+ * required, which is provided as CPUMAP_BUFSIZE.
+ */
+char *cpumap_format(cpumap_t map, char *buf, int size)
+{
+ if (size < CPUMAP_BUFSIZE) {
+ BUG();
+ }
+
+#if CPUMAP_SIZE > 1
+ sprintf(buf, "0x" CPUMAP_FORMAT_STR, map[CPUMAP_SIZE-1]);
+ {
+ int i;
+ char *p = buf + strlen(buf);
+ for (i = CPUMAP_SIZE-2; i >= 0; i--, p += (sizeof(long) + 1)) {
+ sprintf(p, " " CPUMAP_FORMAT_STR, map[i]);
+ }
+ }
+#else
+ sprintf(buf, "0x" CPUMAP_FORMAT_STR, map[0]);
+#endif
+ return(buf);
+}
+
+#if CPUMAP_SIZE > 1
+/*
+ * The following interfaces are provided for (CPUMAP_SIZE > 1).
+ * For the case of (CPUMAP_SIZE==1) (i.e. a single unsigned long),
+ * the same interfaces are provided as inline functions in cpumap.h.
+ */
+int cpumap_is_empty(cpumap_t cpumap)
+{
+ int i;
+ for (i = 0; i < CPUMAP_SIZE; i++) {
+ if (cpumap[i] != 0) {
+ return 0;
+ }
+ }
+ return 1;
+}
+
+/*
+ * Return 1 (non-zero) if they are equal, 0 if not equal
+ */
+int cpumap_cmp_mask(cpumap_t map1, cpumap_t map2)
+{
+ int i;
+ for (i = 0; i < CPUMAP_SIZE; i++) {
+ if (map1[i] != map2[i]) {
+ return 0;
+ }
+ }
+ return 1;
+}
+
+void cpumap_clear_mask(cpumap_t cpumap)
+{
+ int i;
+ for (i = 0; i < CPUMAP_SIZE; i++) {
+ cpumap[i] = 0UL;
+ }
+}
+
+void cpumap_fill(cpumap_t cpumap)
+{
+ int i;
+ for (i = 0; i < (CPUMAP_SIZE - 1); i++) {
+ cpumap[i] = ~0UL;
+ }
+ cpumap[CPUMAP_SIZE - 1] = CPUMAP_FILLMASK;
+}
+
+/*
+ * The following interfaces are optimized for the case where
+ * CPUMAP_SIZE==1 (i.e. a single unsigned long).
+ */
+void cpumap_copy_mask(cpumap_t srcmap, cpumap_t destmap)
+{
+ int i;
+ for (i = 0; i < CPUMAP_SIZE; i++) {
+ destmap[i] = srcmap[i];
+ }
+}
+
+void cpumap_and_mask(cpumap_t map1, cpumap_t map2, cpumap_t result)
+{
+ int i;
+ for (i = 0; i < CPUMAP_SIZE; i++) {
+ result[i] = map1[i] & map2[i];
+ }
+}
+
+#endif
--
Russ Weight