lib/libc/upmap/ukp_clock.c

   1 /*
   2  * Copyright (c) 2014 The DragonFly Project.  All rights reserved.
   3  *
   4  * This code is derived from software contributed to The DragonFly Project
   5  * by Matthew Dillon <dillon@backplane.com>
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  *
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in
  15  *    the documentation and/or other materials provided with the
  16  *    distribution.
  17  * 3. Neither the name of The DragonFly Project nor the names of its
  18  *    contributors may be used to endorse or promote products derived
  19  *    from this software without specific, prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  22  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  23  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  24  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
  25  * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
  26  * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
  27  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  28  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
  29  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  30  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
  31  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  32  * SUCH DAMAGE.
  33  */
  34
  35 /*
  36  * UKP-Optimized clock_gettime().  Use the kpmap after the 10th call.
  37  */
  38
  39 #include <sys/cdefs.h>
  40 #include <sys/types.h>
  41 #include <sys/syscall.h>
  42 #include <sys/upmap.h>
  43 #include <sys/time.h>
  44 #include <machine/cpufunc.h>
  45 #include <errno.h>
  46 #include <time.h>
  47 #include <stdio.h>
  48 #include <unistd.h>
  49 /*#include "un-namespace.h"*/
  50 #include "libc_private.h"
  51 #include "upmap.h"
  52
  53 extern int __sys_clock_gettime(clockid_t clock_id, struct timespec *ts);
  54 int __clock_gettime(clockid_t clock_id, struct timespec *ts);
  55
  56 static int fast_clock;
  57 static int fast_count;
  58 static int *upticksp;
  59 static struct timespec *ts_uptime;
  60 static struct timespec *ts_realtime;
  61
  62 int
  63 __clock_gettime(clockid_t clock_id, struct timespec *ts)
  64 {
  65         int res;
  66         int w;
  67
  68         if (fast_clock == 0 && fast_count++ >= 10) {
  69                 __kpmap_map(&upticksp, &fast_clock, KPTYPE_UPTICKS);
  70                 __kpmap_map(&ts_uptime, &fast_clock, KPTYPE_TS_UPTIME);
  71                 __kpmap_map(&ts_realtime, &fast_clock, KPTYPE_TS_REALTIME);
  72                 __kpmap_map(NULL, &fast_clock, 0);
  73         }
  74         if (fast_clock > 0) {
  75                 switch(clock_id) {
  76                 case CLOCK_UPTIME_FAST:
  77                 case CLOCK_MONOTONIC_FAST:
  78                         do {
  79                                 w = *upticksp;
  80                                 cpu_lfence();
  81                                 *ts = ts_uptime[w & 1];
  82                                 cpu_lfence();
  83                                 w = *upticksp - w;
  84                         } while (w > 1);
  85                         res = 0;
  86                         break;
  87                 case CLOCK_REALTIME_FAST:
  88                 case CLOCK_SECOND:
  89                         do {
  90                                 w = *upticksp;
  91                                 cpu_lfence();
  92                                 *ts = ts_realtime[w & 1];
  93                                 cpu_lfence();
  94                                 w = *upticksp - w;
  95                         } while (w > 1);
  96
  97                         if (clock_id == CLOCK_SECOND)
  98                                 ts->tv_nsec = 0;
  99                         res = 0;
 100                         break;
 101                 default:
 102                         res = __sys_clock_gettime(clock_id, ts);
 103                         break;
 104                 }
 105         } else {
 106                 res = __sys_clock_gettime(clock_id, ts);
 107         }
 108         return res;
 109 }
 110
 111 __weak_reference(__clock_gettime, clock_gettime);