The switchrate option was not implemented in the BPF-based DTrace
implementation. And commit 96d4dfeb (" Eliminate obsolete dt_last*")
removed the dtp->dt_lastswitch member from struct dtrace_hdl. This
patch brings dt_lastswitch back and implements the switchrate option
as a way to limit the frequency of buffer polls.
Signed-off-by: Kris Van Hees <kris.van.hees at oracle.com>
---
libdtrace/dt_consume.c | 30 +++++++++++++++++++++---------
libdtrace/dt_impl.h | 1 +
libdtrace/dt_open.c | 5 +++++
libdtrace/dt_work.c | 1 +
4 files changed, 28 insertions(+), 9 deletions(-)
diff --git a/libdtrace/dt_consume.c b/libdtrace/dt_consume.c
index bc2c6285..1c2223be 100644
--- a/libdtrace/dt_consume.c
+++ b/libdtrace/dt_consume.c
@@ -2986,20 +2986,28 @@ dtrace_workstatus_t
dtrace_consume(dtrace_hdl_t *dtp, FILE *fp, dtrace_consume_probe_f *pf,
dtrace_consume_rec_f *rf, void *arg)
{
- dtrace_optval_t timeout = dtp->dt_options[DTRACEOPT_SWITCHRATE];
+ dtrace_optval_t interval = dtp->dt_options[DTRACEOPT_SWITCHRATE];
+ hrtime_t now = gethrtime();
struct epoll_event events[dtp->dt_conf.num_online_cpus];
int drained = 0;
int i, cnt;
dtrace_workstatus_t rval;
- /*
- * Don't try to consume trace data when tracing hasn't even been
- * started yet. This usually means that the consumer didn't call
- * dtrace_go() yet.
- */
+ /* Has tracing started yet? */
if (!dtp->dt_active)
return dt_set_errno(dtp, EINVAL);
+ if (interval > 0) {
+ if (dtp->dt_lastswitch != 0) {
+ if (now - dtp->dt_lastswitch < interval)
+ return DTRACE_WORKSTATUS_OKAY;
+
+ dtp->dt_lastswitch += interval;
+ } else
+ dtp->dt_lastswitch = now;
+ } else
+ interval = NANOSEC;
+
/*
* Ensure that we have callback functions to use (if none we provided,
* we use the default no-op ones).
@@ -3011,13 +3019,13 @@ dtrace_consume(dtrace_hdl_t *dtp, FILE *fp, dtrace_consume_probe_f *pf,
rf = (dtrace_consume_rec_f *)dt_nullrec;
/*
- * The epoll_wait() function expects the timeout to be expressed in
+ * The epoll_wait() function expects the interval to be expressed in
* milliseconds whereas the switch rate is expressed in nanoseconds.
* We therefore need to convert the value.
*/
- timeout /= NANOSEC / MILLISEC;
+ interval /= NANOSEC / MILLISEC;
cnt = epoll_wait(dtp->dt_poll_fd, events, dtp->dt_conf.num_online_cpus,
- timeout);
+ interval);
if (cnt < 0) {
dt_set_errno(dtp, errno);
return DTRACE_WORKSTATUS_ERROR;
@@ -3037,6 +3045,7 @@ dtrace_consume(dtrace_hdl_t *dtp, FILE *fp, dtrace_consume_probe_f *pf,
}
}
+
/*
* If dtp->dt_beganon is not -1, we did not process the BEGIN probe
* data (if any) yet. We do know (since dtp->dt_active is TRUE) that
@@ -3047,6 +3056,9 @@ dtrace_consume(dtrace_hdl_t *dtp, FILE *fp, dtrace_consume_probe_f *pf,
rval = dt_consume_begin(dtp, fp, events, cnt, pf, rf, arg);
if (rval != 0)
return rval;
+
+ /* Force data retrieval since BEGIN was processed. */
+ dtp->dt_lastswitch = 0;
}
/*
diff --git a/libdtrace/dt_impl.h b/libdtrace/dt_impl.h
index 5d09c6e0..e9e4bbcf 100644
--- a/libdtrace/dt_impl.h
+++ b/libdtrace/dt_impl.h
@@ -391,6 +391,7 @@ struct dtrace_hdl {
void *dt_setoptarg; /* setopt handler argument */
dtrace_status_t dt_status[2]; /* status cache */
int dt_statusgen; /* current status generation */
+ hrtime_t dt_lastswitch; /* last switch of buffer data */
dt_list_t dt_spec_bufs_draining; /* List of spec bufs being drained */
dt_htab_t *dt_spec_bufs;/* spec ID -> list of dt_spec_bufs_head_t */
char *dt_sprintf_buf; /* buffer for dtrace_sprintf() */
diff --git a/libdtrace/dt_open.c b/libdtrace/dt_open.c
index 087af51a..f282c900 100644
--- a/libdtrace/dt_open.c
+++ b/libdtrace/dt_open.c
@@ -796,6 +796,11 @@ dt_vopen(int version, int flags, int *errp,
return set_open_errno(dtp, errp, EDT_READMAXSTACK);
fclose(fd);
+ /*
+ * Set the default data rates.
+ */
+ dtp->dt_options[DTRACEOPT_SWITCHRATE] = NANOSEC;
+
dtp->dt_cpp_argv[0] = (char *)strbasename(dtp->dt_cpp_path);
snprintf(isadef, sizeof(isadef), "-D__SUNW_D_%u",
diff --git a/libdtrace/dt_work.c b/libdtrace/dt_work.c
index 145ce47b..f1292761 100644
--- a/libdtrace/dt_work.c
+++ b/libdtrace/dt_work.c
@@ -173,6 +173,7 @@ dtrace_work(dtrace_hdl_t *dtp, FILE *fp, dtrace_consume_probe_f *pfunc,
switch (dtrace_status(dtp)) {
case DTRACE_STATUS_EXITED:
case DTRACE_STATUS_STOPPED:
+ dtp->dt_lastswitch = 0;
rval = DTRACE_WORKSTATUS_DONE;
break;
case DTRACE_STATUS_NONE:
--
2.39.1