common/sys/clock_impl.h

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*
 * Copyright (c) 2009, 2010, Oracle and/or its affiliates. All rights reserved.
 */

#ifndef _SYS_CLOCK_IMPL_H
#define _SYS_CLOCK_IMPL_H

#ifdef  __cplusplus
extern "C" {
#endif

#if (defined(_KERNEL) || defined(_KMEMUSER))
#include <sys/types.h>
#include <sys/cpuvar.h>
#include <sys/cyclic.h>
#include <sys/time.h>

/*
 * Default clock rate in Hz.
 */
#define HZ_DEFAULT          (100)

/*
 * Thresholds over which we switch between event and cyclic driven lbolt. The
 * current default values were derived experimentally and will keep the
 * system on event driven mode when idle and respond to activity around the
 * lbolt DDI functions by switching to cyclic mode.
 */
#define LBOLT_THRESH_CALLS      (75)
#define LBOLT_THRESH_INTERVAL       (1)

/*
 * Both lbolt_cpu_t and lbolt_info_t are cache line sized and aligned,
 * please take that in consideration if modifying these.
 */
typedef struct lbolt_cpu {
    int64_t lbc_counter;    /* number of calls to the DDI lbolt routines */
    int64_t lbc_cnt_start;  /* beggining of the cnt interval (in ticks) */
    char lbc_pad[CPU_CACHE_COHERENCE_SIZE - (2 * sizeof (int64_t))];
} lbolt_cpu_t;

typedef struct lbolt_info {
    union {
        cyclic_id_t lbi_cyclic_id;  /* lbolt's cyclic id */
        int64_t lbi_id_pad;     /* 64bit padding */
    } id;
    int64_t lbi_thresh_calls;   /* max calls per interval */
    int64_t lbi_thresh_interval;    /* interval window for the # of calls */
    int64_t lbi_debug_ts;       /* last time we dropped into kmdb */
    int64_t lbi_debug_time;     /* time spent in the debugger */
    int64_t lbi_internal;       /* lbolt source when on cyclic mode */
    uint32_t lbi_token;     /* synchronize cyclic mode switch */
    boolean_t lbi_cyc_deactivate;   /* lbolt_cyclic self deactivation */
    int64_t lbi_cyc_deac_start; /* deactivation interval */
} lbolt_info_t;

extern int64_t lbolt_bootstrap(void);
extern int64_t lbolt_event_driven(void);
extern int64_t lbolt_cyclic_driven(void);
extern int64_t (*lbolt_hybrid)(void);
extern uint_t lbolt_ev_to_cyclic(caddr_t, caddr_t);

extern void lbolt_softint_add(void);
extern void lbolt_softint_post(void);

extern void lbolt_debug_entry(void);
extern void lbolt_debug_return(void);

extern lbolt_info_t *lb_info;

/*
 * LBOLT_WAITFREE{,64} provide a non-waiting version of lbolt.
 */
#define LBOLT_WAITFREE64                        \
    (lbolt_hybrid == lbolt_bootstrap ? 0 :              \
    (lbolt_hybrid == lbolt_event_driven ?                           \
        ((gethrtime_waitfree()/nsec_per_tick) -         \
        lb_info->lbi_debug_time) :                  \
        (lb_info->lbi_internal - lb_info->lbi_debug_time)))

#define LBOLT_WAITFREE      (clock_t)LBOLT_WAITFREE64

/*
 * LBOLT_FASTPATH{,64} should *only* be used where the cost of calling the
 * DDI lbolt routines affects performance. This is currently only used by
 * the TCP/IP code and will be removed once it's no longer required.
 */
#define LBOLT_FASTPATH64                        \
    (lbolt_hybrid == lbolt_cyclic_driven ?              \
        (lb_info->lbi_internal - lb_info->lbi_debug_time) :     \
        lbolt_event_driven())

#define LBOLT_FASTPATH      (clock_t)LBOLT_FASTPATH64

/*
 * LBOLT_NO_ACCOUNT{,64} is used by lbolt consumers who fire at a periodic
 * rate, such as clock(), for which the lbolt usage statistics are not updated.
 * This is especially important for consumers whose rate may be modified by
 * the user, resulting in an unaccounted for increase in activity around the
 * lbolt routines that could cause a mode switch.
 */
#define LBOLT_NO_ACCOUNT64                      \
    (lbolt_hybrid == lbolt_bootstrap ? 0 :              \
    (lbolt_hybrid == lbolt_event_driven ?               \
        ((gethrtime()/nsec_per_tick) - lb_info->lbi_debug_time) :   \
        (lb_info->lbi_internal - lb_info->lbi_debug_time)))

#define LBOLT_NO_ACCOUNT    (clock_t)LBOLT_NO_ACCOUNT64

#endif  /* _KERNEL || _KMEMUSER */

#ifdef  __cplusplus
}
#endif

#endif /* _SYS_CLOCK_IMPL_H */