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/*-
* Copyright (c) 2017 Colin Percival
* 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.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/param.h>
#include <sys/sbuf.h>
#include <sys/sysctl.h>
#include <sys/systm.h>
#include <sys/tslog.h>
#include <machine/atomic.h>
#include <machine/cpu.h>
#ifndef TSLOGSIZE
#define TSLOGSIZE 262144
#endif
static volatile long nrecs = 0;
static struct timestamp {
void * td;
int type;
const char * f;
const char * s;
uint64_t tsc;
} timestamps[TSLOGSIZE];
void
tslog(void * td, int type, const char * f, const char * s)
{
uint64_t tsc = get_cyclecount();
long pos;
/* Grab a slot. */
pos = atomic_fetchadd_long(&nrecs, 1);
/* Store record. */
if (pos < nitems(timestamps)) {
timestamps[pos].td = td;
timestamps[pos].type = type;
timestamps[pos].f = f;
timestamps[pos].s = s;
timestamps[pos].tsc = tsc;
}
}
static int
sysctl_debug_tslog(SYSCTL_HANDLER_ARGS)
{
int error;
struct sbuf *sb;
size_t i, limit;
/*
* This code can race against the code in tslog() which stores
* records: Theoretically we could end up reading a record after
* its slots have been reserved but before it has been written.
* Since this code takes orders of magnitude longer to run than
* tslog() takes to write a record, it is highly unlikely that
* anyone will ever experience this race.
*/
sb = sbuf_new_for_sysctl(NULL, NULL, 1024, req);
limit = MIN(nrecs, nitems(timestamps));
for (i = 0; i < limit; i++) {
sbuf_printf(sb, "%p", timestamps[i].td);
sbuf_printf(sb, " %llu",
(unsigned long long)timestamps[i].tsc);
switch (timestamps[i].type) {
case TS_ENTER:
sbuf_printf(sb, " ENTER");
break;
case TS_EXIT:
sbuf_printf(sb, " EXIT");
break;
case TS_THREAD:
sbuf_printf(sb, " THREAD");
break;
case TS_EVENT:
sbuf_printf(sb, " EVENT");
break;
}
sbuf_printf(sb, " %s", timestamps[i].f ? timestamps[i].f : "(null)");
if (timestamps[i].s)
sbuf_printf(sb, " %s\n", timestamps[i].s);
else
sbuf_printf(sb, "\n");
}
error = sbuf_finish(sb);
sbuf_delete(sb);
return (error);
}
SYSCTL_PROC(_debug, OID_AUTO, tslog, CTLTYPE_STRING|CTLFLAG_RD|CTLFLAG_MPSAFE,
0, 0, sysctl_debug_tslog, "", "Dump recorded event timestamps");
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