latencytop/common/dwrapper.c

	dwrapper.c revision de3d2ce46fc25c7b67ccbae4afe5f15e5357568f
/*
 * 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) 2008-2009, Intel Corporation.
 * All Rights Reserved.
 */

#include <unistd.h>
#include <stdio.h>
#include <dtrace.h>
#include <string.h>
#include <stdlib.h>
#include <memory.h>
#include <limits.h>

#include "latencytop.h"

static dtrace_hdl_t *g_dtp = NULL;  /* The dtrace handle */
static pid_t pid_self = -1;     /* PID of our own process */

/*
 * Checks if the process is latencytop itself or sched (if we are not tracing
 * sched), we should ignore them.
 */
#define SHOULD_IGNORE(pid)      \
    ((!g_config.trace_sched && 0 == (pid)) || pid_self == (pid))

/*
 * Get an integer value from dtrace record.
 */
static uint64_t
rec_get_value(void *a, size_t b)
{
    uint64_t ret = 0;

    switch (b) {
    case sizeof (uint64_t):
        ret = *((uint64_t *)(a));
        break;
    case sizeof (uint32_t):
        ret = *((uint32_t *)(a));
        break;
    case sizeof (uint16_t):
        ret = *((uint16_t *)(a));
        break;
    case sizeof (uint8_t):
        ret = *((uint8_t *)(a));
        break;
    default:
        break;
    }

    return (ret);
}

/*
 * Callback to process each aggregation in the snapshot.
 * This one processes lt_call_*, which contains on/off cpu activites.
 */
static int
aggwalk_call(const dtrace_aggdata_t *data, lt_stat_type_t stat_type)
{
    const int REC_PID = 1;
    const int REC_TID = 2;
    const int REC_STACK = 3;
    const int REC_AGG = 4;
    const int NREC = 5;

    dtrace_aggdesc_t *aggdesc = data->dtada_desc;
    dtrace_syminfo_t dts;
    GElf_Sym sym;
    caddr_t addr;
    pid_t pid;
    id_t tid;
    unsigned int stack_depth;
    unsigned int pc_size;
    uint64_t pc;
    uint64_t agg_value;
    char *ptr = NULL;
    char *buffer = NULL;
    int ptrsize;
    unsigned int buffersize;

    if (aggdesc->dtagd_nrecs < NREC) {
        /* Not enough records */
        goto err;
    }

    if (aggdesc->dtagd_rec[REC_PID].dtrd_action != DTRACEACT_DIFEXPR) {
        /* Record is not PID, this is an error. */
        goto err;
    }
    pid = rec_get_value(
        data->dtada_data + aggdesc->dtagd_rec[REC_PID].dtrd_offset,
        aggdesc->dtagd_rec[REC_PID].dtrd_size);
    if (SHOULD_IGNORE(pid)) {
        goto done;
    }

    if (aggdesc->dtagd_rec[REC_TID].dtrd_action != DTRACEACT_DIFEXPR) {
        /* Record is not TID, this is an error. */
        goto err;
    }
    tid = rec_get_value(
        data->dtada_data + aggdesc->dtagd_rec[REC_TID].dtrd_offset,
        aggdesc->dtagd_rec[REC_TID].dtrd_size);

    if (aggdesc->dtagd_rec[REC_STACK].dtrd_action != DTRACEACT_STACK) {
        /* Record is not stack(), this is an error. */
        goto err;
    }

    /* Parse stack array from dtagd_rec */
    stack_depth = aggdesc->dtagd_rec[REC_STACK].dtrd_arg;
    pc_size = aggdesc->dtagd_rec[REC_STACK].dtrd_size / stack_depth;
    addr = data->dtada_data + aggdesc->dtagd_rec[REC_STACK].dtrd_offset;
    buffersize = (stack_depth * (2 * PATH_MAX + 2) + 1) * sizeof (char);
    buffer = (char *)lt_malloc(buffersize);
    ptr = buffer;
    ptrsize = buffersize;

    /* Print the stack */
    while (stack_depth > 0) {
        pc = rec_get_value(addr, pc_size);
        if (pc == 0) {
            break;
        }
        addr += pc_size;
        if (dtrace_lookup_by_addr(g_dtp, pc, &sym, &dts) == 0) {
            int len;
            len = snprintf(ptr, ptrsize,
                "%s`%s ", dts.dts_object, dts.dts_name);
            ptrsize -= len;
            if (ptrsize <= 0) {
                /*
                 * Snprintf returns "desired" length, so
                 * reaching here means our buffer is full.
                 * Move ptr to last byte in the buffer and
                 * break early.
                 */
                ptr = &buffer[buffersize-1];
                break;
            } else  {
                ptr += len;
            }
        }
    }

    if (ptr != buffer) {
        /*
         * We have printed something,
         * so it is safe to remove last ' '.
         */
        *(ptr-1) = 0;
    }

    /* Parsing aggregation data */
    if (!DTRACEACT_ISAGG(aggdesc->dtagd_rec[REC_AGG].dtrd_action)) {
        /* Record is not aggregation, this is an error. */
        goto err;
    }
    agg_value = rec_get_value(
        data->dtada_data + aggdesc->dtagd_rec[REC_AGG].dtrd_offset,
        aggdesc->dtagd_rec[REC_AGG].dtrd_size);

    lt_stat_update(pid, tid, buffer, stat_type, agg_value);

done:
    if (buffer != NULL) {
        free(buffer);
    }
    return (0);

err:
    if (buffer != NULL) {
        free(buffer);
    }
    return (-1);
}

/*
 * Callback to process each aggregation in the snapshot.
 * This one processes lt_named_*, which contains data such as lock spinning.
 */
static int
aggwalk_named(const dtrace_aggdata_t *data, lt_stat_type_t stat_type)
{
    const int REC_PID = 1;
    const int REC_TID = 2;
    const int REC_TYPE = 3;
    const int REC_AGG = 4;
    const int NREC = 5;

    dtrace_aggdesc_t *aggdesc = data->dtada_desc;
    pid_t pid;
    id_t tid;
    uint64_t agg_value;
    int cause_id;
    char *type = NULL;

    if (aggdesc->dtagd_nrecs < NREC) {
        /* Not enough records */
        return (-1);
    }

    if (aggdesc->dtagd_rec[REC_PID].dtrd_action != DTRACEACT_DIFEXPR) {
        /* Record is not PID, this is an error. */
        return (-1);
    }
    pid = rec_get_value(
        data->dtada_data + aggdesc->dtagd_rec[REC_PID].dtrd_offset,
        aggdesc->dtagd_rec[REC_PID].dtrd_size);
    if (SHOULD_IGNORE(pid)) {
        return (0);
    }
    if (aggdesc->dtagd_rec[REC_TID].dtrd_action != DTRACEACT_DIFEXPR) {
        /* Record is not TID, this is an error. */
        return (-1);
    }
    tid = rec_get_value(
        data->dtada_data + aggdesc->dtagd_rec[REC_TID].dtrd_offset,
        aggdesc->dtagd_rec[REC_TID].dtrd_size);

    if (aggdesc->dtagd_rec[REC_TYPE].dtrd_action != DTRACEACT_DIFEXPR) {
        /* Record is not type, this is an error. */
        return (-1);
    }
    type = (char *)data->dtada_data
        + aggdesc->dtagd_rec[REC_TYPE].dtrd_offset;
    cause_id = lt_table_lookup_named_cause(type, 1);

    /* Parsing aggregation data */
    if (!DTRACEACT_ISAGG(aggdesc->dtagd_rec[REC_AGG].dtrd_action)) {
        /* Record is not aggregation, this is an error. */
        return (-1);
    }
    agg_value = rec_get_value(
        data->dtada_data + aggdesc->dtagd_rec[REC_AGG].dtrd_offset,
        aggdesc->dtagd_rec[REC_AGG].dtrd_size);

    lt_stat_update_cause(pid, tid, cause_id, stat_type, agg_value);

    return (0);

}

/*
 * Callback to process each aggregation in the snapshot.
 * This one processes lt_sync_*, which traces synchronization objects.
 */
static int
aggwalk_sync(const dtrace_aggdata_t *data, lt_stat_type_t stat_type)
{
    const int REC_PID = 1;
    const int REC_TID = 2;
    const int REC_STYPE = 3;
    const int REC_WCHAN = 4;
    const int REC_AGG = 5;
    const int NREC = 6;

    dtrace_aggdesc_t *aggdesc = data->dtada_desc;
    pid_t pid;
    id_t tid;
    uint64_t agg_value;
    int stype;
    unsigned long long wchan;

    if (aggdesc->dtagd_nrecs < NREC) {
        /* Not enough records */
        return (-1);
    }

    if (aggdesc->dtagd_rec[REC_PID].dtrd_action != DTRACEACT_DIFEXPR) {
        /* Record is not PID, this is an error. */
        return (-1);
    }
    pid = rec_get_value(
        data->dtada_data + aggdesc->dtagd_rec[REC_PID].dtrd_offset,
        aggdesc->dtagd_rec[REC_PID].dtrd_size);
    if (SHOULD_IGNORE(pid)) {
        return (0);
    }

    if (aggdesc->dtagd_rec[REC_TID].dtrd_action != DTRACEACT_DIFEXPR) {
        /* Record is not TID, this is an error. */
        return (-1);
    }
    tid = rec_get_value(
        data->dtada_data + aggdesc->dtagd_rec[REC_TID].dtrd_offset,
        aggdesc->dtagd_rec[REC_TID].dtrd_size);

    if (aggdesc->dtagd_rec[REC_STYPE].dtrd_action != DTRACEACT_DIFEXPR) {
        /* Record is not stype, this is an error. */
        return (-1);
    }
    stype = rec_get_value(
        data->dtada_data + aggdesc->dtagd_rec[REC_STYPE].dtrd_offset,
        aggdesc->dtagd_rec[REC_STYPE].dtrd_size);

    if (aggdesc->dtagd_rec[REC_WCHAN].dtrd_action != DTRACEACT_DIFEXPR) {
        /* Record is not wchan, this is an error. */
        return (-1);
    }
    wchan = rec_get_value(
        data->dtada_data + aggdesc->dtagd_rec[REC_WCHAN].dtrd_offset,
        aggdesc->dtagd_rec[REC_WCHAN].dtrd_size);

    /* Parsing aggregation data */
    if (!DTRACEACT_ISAGG(aggdesc->dtagd_rec[REC_AGG].dtrd_action)) {
        /* Record is not aggregation, this is an error. */
        return (-1);
    }
    agg_value = rec_get_value(
        data->dtada_data + aggdesc->dtagd_rec[REC_AGG].dtrd_offset,
        aggdesc->dtagd_rec[REC_AGG].dtrd_size);

    lt_stat_update_sobj(pid, tid, stype, wchan, stat_type, agg_value);

    return (0);
}

/*
 * Callback to process each aggregation in the snapshot.
 * This one dispatches to different aggwalk_*().
 */
/* ARGSUSED */
static int
aggwalk(const dtrace_aggdata_t *data, void *arg)
{
    char *tmp;
    char buffer[32];
    lt_stat_type_t stat_type = LT_STAT_COUNT;
    int (*func)(const dtrace_aggdata_t *, lt_stat_type_t);

    (void) strncpy(buffer, data->dtada_desc->dtagd_name, sizeof (buffer));
    buffer[sizeof (buffer) - 1] = 0;

    tmp = strtok(buffer, "_");
    if (strcmp(tmp, "lt") != 0) {
        goto done;
    }

    tmp = strtok(NULL, "_");
    if (strcmp(tmp, "call") == 0) {
        func = aggwalk_call;
    } else if (strcmp(tmp, "named") == 0) {
        func = aggwalk_named;
    } else if (strcmp(tmp, "sync") == 0) {
        func = aggwalk_sync;
    } else {
        goto done;
    }

    tmp = strtok(NULL, "_");
    if (strcmp(tmp, "count") == 0) {
        stat_type = LT_STAT_COUNT;
    } else if (strcmp(tmp, "sum") == 0) {
        stat_type = LT_STAT_SUM;
    } else if (strcmp(tmp, "max") == 0) {
        stat_type = LT_STAT_MAX;
    } else {
        goto done;
    }

    (void) func(data, stat_type);

done:
    /* We have our data, remove it from DTrace. */
    return (DTRACE_AGGWALK_REMOVE);
}

/*
 * Callback to handle DTrace drop data events.
 */
/*ARGSUSED*/
static int
drop_handler(const dtrace_dropdata_t *data, void *user)
{
    lt_display_error("Drop: %s\n", data->dtdda_msg);
    /*
     * Pretend nothing happened. So our program can continue.
     */
    return (DTRACE_HANDLE_OK);
}

/*
 * DTrace initialization. The D script is running when this function returns.
 */
int
lt_dtrace_init(void)
{
    dtrace_prog_t *prog;
    dtrace_proginfo_t info;
    int err;
    FILE *fp_script = NULL;

    pid_self = getpid();
    /* Open dtrace, set up handler */
    g_dtp = dtrace_open(DTRACE_VERSION, 0, &err);
    if (g_dtp == NULL) {
        lt_display_error("Cannot open dtrace library: %s\n",
            dtrace_errmsg(NULL, err));
        return (-1);
    }

    if (dtrace_handle_drop(g_dtp, &drop_handler, NULL) == -1) {
        lt_display_error("Cannot install DTrace handle: %s\n",
            dtrace_errmsg(NULL, err));
        return (-1);
    }

    /* Load D script, set up macro and compile */
#ifdef EMBED_CONFIGS
    /* Create a temp file because libdtrace use cpp(1) on files only. */
    fp_script = tmpfile();
    if (fp_script == NULL) {
        lt_display_error("Cannot create tmp file\n");
        return (-1);
    }
    (void) fwrite(latencytop_d, latencytop_d_len, 1, fp_script);
    (void) fseek(fp_script, 0, SEEK_SET);
#else
    fp_script = fopen(DEFAULT_D_SCRIPT_NAME, "r");
    if (fp_script == NULL) {
        lt_display_error("Cannot open script file %s\n",
            DEFAULT_D_SCRIPT_NAME);
        return (-1);
    }
#endif  /* EMBED_CONFIGS */

    if (g_config.enable_filter) {
        (void) dtrace_setopt(g_dtp, "define", "ENABLE_FILTER");
    }
    if (g_config.trace_syncobj) {
        (void) dtrace_setopt(g_dtp, "define", "ENABLE_SYNCOBJ");
    }
    if (g_config.trace_sched) {
        (void) dtrace_setopt(g_dtp, "define", "ENABLE_SCHED");
    }
    if (g_config.low_overhead_mode) {
        (void) dtrace_setopt(g_dtp, "define", "ENABLE_LOW_OVERHEAD");
    }

    prog = dtrace_program_fcompile(g_dtp, fp_script,
        DTRACE_C_CPP, 0, NULL);
    (void) fclose(fp_script);
    if (prog == NULL) {
        lt_display_error("Failed to compile D script.\n");
        return (dtrace_errno(g_dtp));
    }

    /* Execute the D script */
    if (dtrace_program_exec(g_dtp, prog, &info) == -1) {
        lt_display_error("Failed to enable probes.\n");
        return (dtrace_errno(g_dtp));
    }
    if (dtrace_go(g_dtp) != 0) {
        lt_display_error("Failed to run D script.\n");
        return (dtrace_errno(g_dtp));
    }
    return (0);
}

/*
 * Worker function to move aggregator data to user space.
 * Needs to be called periodically to prevent running out of kernel memory.
 */
int
lt_dtrace_work(int force)
{
    static uint64_t last_snap = 0;
    uint64_t now = lt_millisecond();

    if (!force && now - last_snap < g_config.snap_interval) {
        return (last_snap + g_config.snap_interval - now);
    }

    if (dtrace_status(g_dtp) == -1) {
        lt_display_error("Failed when getting status: %s\n",
            dtrace_errmsg(g_dtp, dtrace_errno(g_dtp)));
        return (-1);
    }

    if (dtrace_aggregate_snap(g_dtp) != 0) {
        lt_display_error("Failed to snap aggregate: %s\n",
            dtrace_errmsg(g_dtp, dtrace_errno(g_dtp)));
        return (-1);
    }

    last_snap = now;
    return (0);
}

/*
 * Walk through aggregator and collect data to LatencyTOP.
 * Different from lt_dtrace_work, this one moves data from libdtrace
 * to latencytop.
 * This needs to be called immediately before update UI.
 */
int
lt_dtrace_collect(void)
{
    if (lt_dtrace_work(1) != 0) {
        return (-1);
    }

    if (dtrace_aggregate_walk(g_dtp, aggwalk, NULL) != 0) {
        lt_display_error("Failed to sort aggregate: %s\n",
            dtrace_errmsg(g_dtp, dtrace_errno(g_dtp)));
        return (-1);
    }

    /*
     * Probably no need to clear again, because we removed everything.
     * Paranoid.
     */
    dtrace_aggregate_clear(g_dtp);

    return (0);
}

/*
 * Clean up and close DTrace.
 */
void
lt_dtrace_deinit(void)
{
    (void) dtrace_stop(g_dtp);
    dtrace_close(g_dtp);
}