])
_AC_DEFINE_AND_SUBST([LTTNG_UST_DEFAULT_CONSTRUCTOR_TIMEOUT_MS], [3000])
+# By default, do not retry on buffer full condition.
+_AC_DEFINE_AND_SUBST([LTTNG_UST_DEFAULT_BLOCKING_RETRY_TIMEOUT_MS], [0])
AC_CONFIG_FILES([
Makefile
# Tools to execute:
ADOC = $(ASCIIDOC) -f $(ASCIIDOC_CONF) -d manpage \
-a lttng_version="$(PACKAGE_VERSION)" \
- -a lttng_ust_register_timeout="@LTTNG_UST_DEFAULT_CONSTRUCTOR_TIMEOUT_MS@"
+ -a lttng_ust_register_timeout="@LTTNG_UST_DEFAULT_CONSTRUCTOR_TIMEOUT_MS@" \
+ -a lttng_ust_blocking_retry_timeout="@LTTNG_UST_DEFAULT_BLOCKING_RETRY_TIMEOUT_MS@"
+
ADOC_DOCBOOK = $(ADOC) -b docbook
XTO = $(XMLTO) -m $(firstword $(XSL_SRC_FILES)) man
are located in a specific directory under `$LTTNG_HOME` (or `$HOME` if
`$LTTNG_HOME` is not set).
+`LTTNG_UST_BLOCKING_RETRY_TIMEOUT`::
+ Maximum duration (milliseconds) to retry event tracing when
+ there's no space left for the event record in the sub-buffer.
++
+--
+`0` (default)::
+ Never block the application.
+
+Positive value::
+ Block the application for the specified number of milliseconds. If
+ there's no space left after this duration, discard the event
+ record.
+
+Negative value::
+ Block the application until there's space left for the event record.
+--
++
+This option can be useful in workloads generating very large trace data
+throughput, where blocking the application is an acceptable trade-off to
+prevent discarding event records.
++
+WARNING: Setting this environment variable to a non-zero value may
+significantly affect application timings.
+
`LTTNG_UST_CLOCK_PLUGIN`::
Path to the shared object which acts as the clock override plugin.
An example of such a plugin can be found in the LTTng-UST
+
Default: {lttng_ust_register_timeout}.
+`LTTNG_UST_BLOCKING_RETRY_TIMEOUT`::
+ Maximum time during which event tracing retry is attempted on buffer
+ full condition (millliseconds). Setting this environment to non-zero
+ value effectively blocks the application on buffer full condition.
+ Setting this environment variable to non-zero values may
+ significantly affect application timings. Setting this to a negative
+ value may block the application indefinitely if there is no consumer
+ emptying the ring buffer. The delay between retry attempts is the
+ minimum between the specified timeout value and 100ms. This option
+ can be useful in workloads generating very large trace data
+ throughput, where blocking the application is an acceptable
+ trade-off to not discard events. _Use with caution_.
++
+The value `0` means _do not retry_. The value `-1` means _retry forever_.
+Value > `0` means a maximum timeout of the given value.
++
+Default: {lttng_ust_blocking_retry_timeout}.
+
`LTTNG_UST_WITHOUT_BADDR_STATEDUMP`::
Prevents `liblttng-ust` from performing a base address state dump
(see the <<state-dump,LTTng-UST state dump>> section above) if
#include <time.h>
#include <assert.h>
#include <signal.h>
+#include <limits.h>
#include <urcu/uatomic.h>
#include <urcu/futex.h>
#include <urcu/compiler.h>
#include "tracepoint-internal.h"
#include "lttng-tracer-core.h"
#include "compat.h"
-#include "../libringbuffer/tlsfixup.h"
+#include "../libringbuffer/rb-init.h"
#include "lttng-ust-statedump.h"
#include "clock.h"
#include "../libringbuffer/getcpu.h"
return 1;
}
+static
+void get_blocking_retry_timeout(void)
+{
+ const char *str_blocking_retry_timeout =
+ lttng_secure_getenv("LTTNG_UST_BLOCKING_RETRY_TIMEOUT");
+
+ if (str_blocking_retry_timeout) {
+ long timeout = strtol(str_blocking_retry_timeout, NULL, 10);
+
+ if (timeout < 0)
+ timeout = -1;
+ if (timeout > INT_MAX) {
+ WARN("Saturating %s value from %ld to %d\n",
+ "LTTNG_UST_BLOCKING_RETRY_TIMEOUT",
+ timeout, INT_MAX);
+ timeout = INT_MAX;
+ }
+ DBG("%s environment variable value is %ld",
+ "LTTNG_UST_BLOCKING_RETRY_TIMEOUT",
+ timeout);
+ lttng_ust_ringbuffer_set_retry_timeout(timeout);
+ }
+}
+
static
int register_to_sessiond(int socket, enum ustctl_socket_type type)
{
timeout_mode = get_constructor_timeout(&constructor_timeout);
+ get_blocking_retry_timeout();
+
ret = sem_init(&constructor_wait, 0, 0);
if (ret) {
PERROR("sem_init");
api.h \
backend.h backend_internal.h backend_types.h \
frontend_api.h frontend.h frontend_internal.h frontend_types.h \
- nohz.h vatomic.h tlsfixup.h
+ nohz.h vatomic.h rb-init.h
libringbuffer_la_LIBADD = \
-lpthread \
--- /dev/null
+#ifndef _LTTNG_UST_LIB_RINGBUFFER_RB_INIT_H
+#define _LTTNG_UST_LIB_RINGBUFFER_RB_INIT_H
+
+/*
+ * libringbuffer/rb-init.h
+ *
+ * Copyright (C) 2012-2016 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; only
+ * version 2.1 of the License.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+void lttng_fixup_ringbuffer_tls(void);
+void lttng_ust_ringbuffer_set_retry_timeout(int timeout);
+
+#endif /* _LTTNG_UST_LIB_RINGBUFFER_RB_INIT_H */
#include "backend.h"
#include "frontend.h"
#include "shm.h"
-#include "tlsfixup.h"
+#include "rb-init.h"
#include "../liblttng-ust/compat.h" /* For ENODATA */
/* Print DBG() messages about events lost only every 1048576 hits */
#define CLOCKID CLOCK_MONOTONIC
#define LTTNG_UST_RING_BUFFER_GET_RETRY 10
#define LTTNG_UST_RING_BUFFER_RETRY_DELAY_MS 10
+#define RETRY_DELAY_MS 100 /* 100 ms. */
/*
* Non-static to ensure the compiler does not optimize away the xor.
.lock = PTHREAD_MUTEX_INITIALIZER,
};
+int lttng_ust_blocking_retry_timeout =
+ CONFIG_LTTNG_UST_DEFAULT_BLOCKING_RETRY_TIMEOUT_MS;
+
+void lttng_ust_ringbuffer_set_retry_timeout(int timeout)
+{
+ lttng_ust_blocking_retry_timeout = timeout;
+}
+
/**
* lib_ring_buffer_reset - Reset ring buffer to initial values.
* @buf: Ring buffer.
lib_ring_buffer_switch_old_end(buf, chan, &offsets, tsc, handle);
}
+static
+bool handle_blocking_retry(int *timeout_left_ms)
+{
+ int timeout = *timeout_left_ms, delay;
+
+ if (caa_likely(!timeout))
+ return false; /* Do not retry, discard event. */
+ if (timeout < 0) /* Wait forever. */
+ delay = RETRY_DELAY_MS;
+ else
+ delay = min_t(int, timeout, RETRY_DELAY_MS);
+ (void) poll(NULL, 0, delay);
+ if (timeout > 0)
+ *timeout_left_ms -= delay;
+ return true; /* Retry. */
+}
+
/*
* Returns :
* 0 if ok
const struct lttng_ust_lib_ring_buffer_config *config = &chan->backend.config;
struct lttng_ust_shm_handle *handle = ctx->handle;
unsigned long reserve_commit_diff, offset_cmp;
+ int timeout_left_ms = lttng_ust_blocking_retry_timeout;
retry:
offsets->begin = offset_cmp = v_read(config, &buf->offset);
>= chan->backend.buf_size)) {
unsigned long nr_lost;
+ if (handle_blocking_retry(&timeout_left_ms))
+ goto retry;
+
/*
* We do not overwrite non consumed buffers
* and we are full : record is lost.
+++ /dev/null
-#ifndef _LTTNG_UST_LIB_RINGBUFFER_TLS_FIXUP_H
-#define _LTTNG_UST_LIB_RINGBUFFER_TLS_FIXUP_H
-
-/*
- * libringbuffer/tlsfixup.h
- *
- * Copyright (C) 2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
- *
- * This library is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Lesser General Public
- * License as published by the Free Software Foundation; only
- * version 2.1 of the License.
- *
- * This library is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- * Lesser General Public License for more details.
- *
- * You should have received a copy of the GNU Lesser General Public
- * License along with this library; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
- */
-
-void lttng_fixup_ringbuffer_tls(void);
-
-#endif /* _LTTNG_UST_LIB_RINGBUFFER_TLS_FIXUP_H */
projects / lttng-ust.git / commitdiff
