FreeBSD/Linux Kernel Cross Reference
sys/sys/gmon.h

     /*-
      * SPDX-License-Identifier: BSD-3-Clause
      *
      * Copyright (c) 1982, 1986, 1992, 1993
      *      The Regents of the University of California.  All rights reserved.
      *
      * Redistribution and use in source and binary forms, with or without
      * modification, are permitted provided that the following conditions
      * are met:
     * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     * 3. Neither the name of the University nor the names of its contributors
     *    may be used to endorse or promote products derived from this software
     *    without specific prior written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     *
     *      @(#)gmon.h      8.2 (Berkeley) 1/4/94
     * $FreeBSD$
     */
    
    #ifndef _SYS_GMON_H_
    #define _SYS_GMON_H_
    
    #include <machine/profile.h>
    
    /*
     * Structure prepended to gmon.out profiling data file.
     */
    struct gmonhdr {
            u_long  lpc;            /* base pc address of sample buffer */
            u_long  hpc;            /* max pc address of sampled buffer */
            int     ncnt;           /* size of sample buffer (plus this header) */
            int     version;        /* version number */
            int     profrate;       /* profiling clock rate */
            int     histcounter_type; /* size (in bits) and sign of HISTCOUNTER */
            int     spare[2];       /* reserved */
    };
    #define GMONVERSION     0x00051879
    
    /*
     * Type of histogram counters used in the kernel.
     */
    #ifdef GPROF4
    #define HISTCOUNTER     int64_t
    #else
    #define HISTCOUNTER     unsigned short
    #endif
    
    /*
     * Fraction of text space to allocate for histogram counters.
     * We allocate counters at the same or higher density as function
     * addresses, so that each counter belongs to a unique function.
     * A lower density of counters would give less resolution but a
     * higher density would be wasted.
     */
    #define HISTFRACTION    (FUNCTION_ALIGNMENT / sizeof(HISTCOUNTER) == 0 \
                             ? 1 : FUNCTION_ALIGNMENT / sizeof(HISTCOUNTER))
    
    /*
     * Fraction of text space to allocate for from hash buckets.
     * The value of HASHFRACTION is based on the minimum number of bytes
     * of separation between two subroutine call points in the object code.
     * Given MIN_SUBR_SEPARATION bytes of separation the value of
     * HASHFRACTION is calculated as:
     *
     *      HASHFRACTION = MIN_SUBR_SEPARATION / (2 * sizeof(short) - 1);
     *
     * For example, on the VAX, the shortest two call sequence is:
     *
     *      calls   $0,(r0)
     *      calls   $0,(r0)
     *
     * which is separated by only three bytes, thus HASHFRACTION is
     * calculated as:
     *
     *      HASHFRACTION = 3 / (2 * 2 - 1) = 1
     *
     * Note that the division above rounds down, thus if MIN_SUBR_FRACTION
     * is less than three, this algorithm will not work!
     *
     * In practice, however, call instructions are rarely at a minimal
     * distance.  Hence, we will define HASHFRACTION to be 2 across all
     * architectures.  This saves a reasonable amount of space for
     * profiling data structures without (in practice) sacrificing
     * any granularity.
    */
   /*
    * XXX I think the above analysis completely misses the point.  I think
    * the point is that addresses in different functions must hash to
    * different values.  Since the hash is essentially division by
    * sizeof(unsigned short), the correct formula is:
    *
    *      HASHFRACTION = MIN_FUNCTION_ALIGNMENT / sizeof(unsigned short)
    *
    * Note that he unsigned short here has nothing to do with the one for
    * HISTFRACTION.
    *
    * Hash collisions from a two call sequence don't matter.  They get
    * handled like collisions for calls to different addresses from the
    * same address through a function pointer.
    */
   #define HASHFRACTION    (FUNCTION_ALIGNMENT / sizeof(unsigned short) == 0 \
                            ? 1 : FUNCTION_ALIGNMENT / sizeof(unsigned short))
   
   /*
    * percent of text space to allocate for tostructs with a minimum.
    */
   #define ARCDENSITY      2
   #define MINARCS         50
   
   /*
    * Limit on the number of arcs to so that arc numbers can be stored in
    * `*froms' and stored and incremented without overflow in links.
    */
   #define MAXARCS         (((u_long)1 << (8 * sizeof(u_short))) - 2)
   
   struct tostruct {
           u_long  selfpc;
           long    count;
           u_short link;
           u_short pad;
   };
   
   /*
    * a raw arc, with pointers to the calling site and
    * the called site and a count.
    */
   struct rawarc {
           u_long  raw_frompc;
           u_long  raw_selfpc;
           long    raw_count;
   };
   
   /*
    * general rounding functions.
    */
   #define ROUNDDOWN(x,y)  rounddown(x,y)
   #define ROUNDUP(x,y)    roundup(x,y)
   
   /*
    * The profiling data structures are housed in this structure.
    */
   struct gmonparam {
           int             state;
           HISTCOUNTER     *kcount;
           u_long          kcountsize;
           u_short         *froms;
           u_long          fromssize;
           struct tostruct *tos;
           u_long          tossize;
           long            tolimit;
           uintfptr_t      lowpc;
           uintfptr_t      highpc;
           u_long          textsize;
           u_long          hashfraction;
           int             profrate;       /* XXX wrong type to match gmonhdr */
           HISTCOUNTER     *cputime_count;
           int             cputime_overhead;
           HISTCOUNTER     *mcount_count;
           int             mcount_overhead;
           int             mcount_post_overhead;
           int             mcount_pre_overhead;
           HISTCOUNTER     *mexitcount_count;
           int             mexitcount_overhead;
           int             mexitcount_post_overhead;
           int             mexitcount_pre_overhead;
           int             histcounter_type;
   };
   extern struct gmonparam _gmonparam;
   
   /*
    * Possible states of profiling.
    */
   #define GMON_PROF_ON    0
   #define GMON_PROF_BUSY  1
   #define GMON_PROF_ERROR 2
   #define GMON_PROF_OFF   3
   #define GMON_PROF_HIRES 4
   
   /*
    * Sysctl definitions for extracting profiling information from the kernel.
    */
   #define GPROF_STATE     0       /* int: profiling enabling variable */
   #define GPROF_COUNT     1       /* struct: profile tick count buffer */
   #define GPROF_FROMS     2       /* struct: from location hash bucket */
   #define GPROF_TOS       3       /* struct: destination/count structure */
   #define GPROF_GMONPARAM 4       /* struct: profiling parameters (see above) */
   
   #ifdef _KERNEL
   
   #define KCOUNT(p,index) \
           ((p)->kcount[(index) / (HISTFRACTION * sizeof(HISTCOUNTER))])
   #define PC_TO_I(p, pc)  ((uintfptr_t)(pc) - (uintfptr_t)(p)->lowpc)
   
   #ifdef GUPROF
   
   #define CALIB_SCALE     1000
   
   extern int      cputime_bias;
   
   int     cputime(void);
   void    nullfunc_loop_profiled(void);
   void    nullfunc_profiled(void);
   void    startguprof(struct gmonparam *p);
   void    stopguprof(struct gmonparam *p);
   
   #else /* !GUPROF */
   
   #define startguprof(p)
   #define stopguprof(p)
   
   #endif /* GUPROF */
   
   void    empty_loop(void);
   void    kmupetext(uintfptr_t nhighpc);
   void    mexitcount(uintfptr_t selfpc);
   void    nullfunc(void);
   void    nullfunc_loop(void);
   
   #else /* !_KERNEL */
   
   #include <sys/cdefs.h>
   
   __BEGIN_DECLS
   void    moncontrol(int);
   void    monstartup(u_long, u_long);
   __END_DECLS
   
   #endif /* _KERNEL */
   
   #endif /* !_SYS_GMON_H_ */

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