Hi,
This patch applies to the 2.5.2 kernel.
This patch implements a scalable bitmask specifically
for tracking CPUs. It consists of a single file which simply
adds a new datatype and supporting functions. It allows 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 functions are optimized at compile-time according to
the definition of NR_CPUS.
While systems with more than 32 processors are still
out in the future, these interfaces provide a path for gradual
code migration. One of the primary goals is to provide current
functionality without affecting performance.
A preliminary list of global CPU bitmasks which _could_
migrate to this new datatype are listed below.
phys_cpu_present_map
cpu_initialized
wait_init_idle
cpu_online_map/cpu_present_mask
cpu_callin_map
cpu_callout_map
*** I have been working on patches for some of these bitmasks,
*** and will send out the one for phys_cpu_present_map as an
*** example.
One question that has arisen is whether or not a more
generic datatype and interface set could be provided for bitmasks
in general. I considered this, but could not find sufficient
justification for doing so. However, it would be very easy to
break out the generic portions of these functions into lower-level
primitives that could be more generally used.
NOTE: The cpumap_to_ulong() and cpumap_ulong_to_cpumap() interfaces
are provided specifically for migration. In their current form,
they call BUG() if NR_CPUS is defined to be greater than the
bit-size of (unsigned long).
Your comments are welcome! Please let me know what you think...
-- Russ Weight (rweight@us.ibm.com) Linux Technology Centerdiff -u lx252.pure/include/linux/cpumap.h linux/include/linux/cpumap.h --- lx252.pure/include/linux/cpumap.h Thu Jan 24 16:17:32 2002 +++ linux/include/linux/cpumap.h Fri Jan 25 16:40:44 2002 @@ -0,0 +1,246 @@ +/* + * cpumap_t data type and supporting functions + * + * Copyright (c) 2001 IBM Corp. + * + * 01/25/02 Initial Version Russ Weight <rweight@us.ibm.com> + * + * 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 + +#ifdef CONFIG_SMP + #include <asm/types.h> + #define CPUMAP_SIZE ((NR_CPUS + BITS_PER_LONG - 1) / BITS_PER_LONG) +#else + #define CPUMAP_SIZE 1 +#endif + +#ifndef __ASSEMBLY__ +#include <linux/bitops.h> +typedef unsigned long cpumap_t[CPUMAP_SIZE]; + +/* + * The cpumap_to_ulong() and cpumap_ulong_to_cpumap() functions + * are provided primarily for migration to the cpumap_t datatype. + * As currently defined, they are only valid for CPUMAP_SIZE==1. + */ +static inline unsigned long cpumap_to_ulong(cpumap_t cpumap) +{ +#if CPUMAP_SIZE > 1 + BUG(); /* Not supported */ + return 0; +#else + return cpumap[0]; +#endif +} + +static inline void cpumap_ulong_to_cpumap(unsigned long bitmap, cpumap_t cpumap) +{ +#if CPUMAP_SIZE > 1 + BUG(); /* Not supported */ +#else + cpumap[0] = bitmap; +#endif +} + + +/* + * The first set of interfaces are the same for SMP and UP. + */ +static inline void cpumap_clear_bit(int nr, cpumap_t cpumap) +{ + if (nr < NR_CPUS) { + clear_bit(nr, cpumap); + } else { + BUG(); + } +} + +static inline void cpumap_set_bit(int nr, cpumap_t cpumap) +{ + if (nr < NR_CPUS) { + set_bit(nr, cpumap); + } else { + BUG(); + } +} + +static inline int cpumap_test_and_set_bit(int nr, cpumap_t cpumap) +{ + if (nr < NR_CPUS) { + return test_and_set_bit(nr, cpumap); + } else { + BUG(); + return -1; + } +} + +/* + * Return 1 (non-zero) if they are equal, 0 if not equal + */ +static inline int cpumap_test_bit(int nr, cpumap_t cpumap) +{ + if (nr < NR_CPUS) { + return test_bit(nr, cpumap); + } else { + return 0; + } +} + +/* + * 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. + */ +static inline void cpumap_clear_mask(cpumap_t cpumap) +{ +#if CPUMAP_SIZE > 1 + int i; + + for (i = 0; i < CPUMAP_SIZE; i++) { + cpumap[i] = 0UL; + } +#else + cpumap[0] = 0; +#endif +} + +static inline int cpumap_is_empty(cpumap_t map) +{ +#if CPUMAP_SIZE > 1 + int i; + for (i = 0; i < CPUMAP_SIZE; i++) { + if (map[i] != 0) { + return 0; + } + } + return 1; +#else + return (map[0] == 0); +#endif +} + +/* + * Return 1 (non-zero) if they are equal, 0 if not equal + */ +static inline int cpumap_cmp_mask(cpumap_t map1, cpumap_t map2) +{ +#if CPUMAP_SIZE > 1 + int i; + for (i = 0; i < CPUMAP_SIZE; i++) { + if (map1[i] != map2[i]) { + return 0; + } + } + return 1; +#else + return (map1[0] == map2[0]); +#endif +} + +#if (NR_CPUS % BITS_PER_LONG) +#define CPUMAP_FILLMASK ((1 << (NR_CPUS % BITS_PER_LONG)) -1) +#else +#define CPUMAP_FILLMASK (~0UL) +#endif + +static inline void cpumap_fill(cpumap_t cpumap) +{ +#if CPUMAP_SIZE > 1 + int i; + + for (i = 0; i < (CPUMAP_SIZE - 1); i++) { + cpumap[i] = ~0UL; + } + cpumap[CPUMAP_SIZE - 1] = CPUMAP_FILLMASK; +#else + cpumap[0] = CPUMAP_FILLMASK; +#endif +} + +/* + * The following interfaces are optimized for the case where + * CPUMAP_SIZE==1 (i.e. a single unsigned long). + */ +static inline void cpumap_copy_mask(cpumap_t srcmap, cpumap_t destmap) +{ +#if CPUMAP_SIZE > 1 + int i; + for (i = 0; i < CPUMAP_SIZE; i++) { + destmap[i] = srcmap[i]; + } +#else + destmap[0] = srcmap[0]; +#endif +} + +static inline void cpumap_and_mask(cpumap_t map1, cpumap_t map2, cpumap_t result) +{ +#if CPUMAP_SIZE > 1 + int i; + for (i = 0; i < CPUMAP_SIZE; i++) { + result[i] = map1[i] & map2[i]; + } +#else + result[0] = map1[0] & map2[0]; +#endif +} + +/* + * The following macros and functions 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 + +static inline 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); +} + +#endif /* __ASSEMBLY__ */ +#endif /* __LINUX_CPUMAP_H */ - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
This archive was generated by hypermail 2b29 : Thu Jan 31 2002 - 21:00:56 EST