[lttng-dev] [PATCH lttng-tools 2/4] Move add data stream to the data thread
David Goulet
dgoulet at efficios.com
Mon Oct 15 13:40:52 EDT 2012
Mathieu Desnoyers:
> * David Goulet (dgoulet at efficios.com) wrote:
>>
>>
>> Mathieu Desnoyers:
>>> * David Goulet (dgoulet at efficios.com) wrote:
>>>> As a second step of refactoring, upon receiving a data stream, we send
>>>> it to the data thread that is now in charge of handling it.
>>>>
>>>> Furthermore, in order for this to behave correctly, we have to make the
>>>> ustctl actions on the stream upon before passing it to the right thread
>>>> (the kernel does not need special actions.). This way, once the sessiond
>>>> thread reply back to the session daemon, the stream is sure to be open
>>>> and ready for data to be recorded on the application side so we avoid a
>>>> race between the application thinking the stream is ready and the stream
>>>> thread still scheduled out.
>>>
>>> Normally, as long as we have a reference on the SHM file descriptor, and
>>> we have the wakeup FD, we should be good to fetch the data of buffers
>>> belonging to an application that has already exited, even if it did so
>>> before the ustctl calls are done.
>>>
>>> So I'm wondering why you do the ustctl calls in the sessiond thread ? It
>>> seems to complexify the implementation needlessly: we could still do the
>>> ustctl calls and output file open at the same location, the
>>> data/metadata threads.
>>
>> Hmmm, it was my understanding that does
>
> does -> those
>
>> ustctl_* calls were needed
>> before the trace could be recording thus making them quickly. Wrong?
>
> Can you rephrase your question ? I don't understand.
>
My understanding was that _those_ ustctl calls need to be done before
the tracer could start recording data. This is why they were moved to
the session daemon thread.
Am I wrong here? When receiving an UST stream< on the consumer side, is
the SHM reference already acquired?
David
> Thanks,
>
> Mathieu
>
>>
>> David
>>
>>>
>>> Thanks,
>>>
>>> Mathieu
>>>
>>>>
>>>> This commit should speed up the add stream process for the session
>>>> daemon. There is still some actions to move out of the session daemon
>>>> poll thread to gain speed significantly, especially for network
>>>> streaming.
>>>>
>>>> Signed-off-by: David Goulet <dgoulet at efficios.com>
>>>> ---
>>>> src/common/consumer.c | 123 +++++++++++---------------
>>>> src/common/consumer.h | 1 +
>>>> src/common/kernel-consumer/kernel-consumer.c | 24 ++---
>>>> src/common/ust-consumer/ust-consumer.c | 40 ++++-----
>>>> 4 files changed, 78 insertions(+), 110 deletions(-)
>>>>
>>>> diff --git a/src/common/consumer.c b/src/common/consumer.c
>>>> index 055de1b..1d2b1f7 100644
>>>> --- a/src/common/consumer.c
>>>> +++ b/src/common/consumer.c
>>>> @@ -89,7 +89,7 @@ static struct lttng_consumer_stream *consumer_find_stream(int key,
>>>> return stream;
>>>> }
>>>>
>>>> -static void consumer_steal_stream_key(int key, struct lttng_ht *ht)
>>>> +void consumer_steal_stream_key(int key, struct lttng_ht *ht)
>>>> {
>>>> struct lttng_consumer_stream *stream;
>>>>
>>>> @@ -409,6 +409,14 @@ struct lttng_consumer_stream *consumer_allocate_stream(
>>>> lttng_ht_node_init_ulong(&stream->waitfd_node, stream->wait_fd);
>>>> lttng_ht_node_init_ulong(&stream->node, stream->key);
>>>>
>>>> + /*
>>>> + * The cpu number is needed before using any ustctl_* actions. Ignored for
>>>> + * the kernel so the value does not matter.
>>>> + */
>>>> + pthread_mutex_lock(&consumer_data.lock);
>>>> + stream->cpu = stream->chan->cpucount++;
>>>> + pthread_mutex_unlock(&consumer_data.lock);
>>>> +
>>>> DBG3("Allocated stream %s (key %d, shm_fd %d, wait_fd %d, mmap_len %llu,"
>>>> " out_fd %d, net_seq_idx %d)", stream->path_name, stream->key,
>>>> stream->shm_fd, stream->wait_fd,
>>>> @@ -437,28 +445,6 @@ int consumer_add_stream(struct lttng_consumer_stream *stream)
>>>> pthread_mutex_lock(&consumer_data.lock);
>>>> rcu_read_lock();
>>>>
>>>> - switch (consumer_data.type) {
>>>> - case LTTNG_CONSUMER_KERNEL:
>>>> - break;
>>>> - case LTTNG_CONSUMER32_UST:
>>>> - case LTTNG_CONSUMER64_UST:
>>>> - stream->cpu = stream->chan->cpucount++;
>>>> - ret = lttng_ustconsumer_add_stream(stream);
>>>> - if (ret) {
>>>> - ret = -EINVAL;
>>>> - goto error;
>>>> - }
>>>> -
>>>> - /* Steal stream identifier only for UST */
>>>> - consumer_steal_stream_key(stream->key, consumer_data.stream_ht);
>>>> - break;
>>>> - default:
>>>> - ERR("Unknown consumer_data type");
>>>> - assert(0);
>>>> - ret = -ENOSYS;
>>>> - goto error;
>>>> - }
>>>> -
>>>> lttng_ht_add_unique_ulong(consumer_data.stream_ht, &stream->node);
>>>>
>>>> /* Check and cleanup relayd */
>>>> @@ -485,7 +471,6 @@ int consumer_add_stream(struct lttng_consumer_stream *stream)
>>>> consumer_data.stream_count++;
>>>> consumer_data.need_update = 1;
>>>>
>>>> -error:
>>>> rcu_read_unlock();
>>>> pthread_mutex_unlock(&consumer_data.lock);
>>>>
>>>> @@ -1582,17 +1567,6 @@ void consumer_del_metadata_stream(struct lttng_consumer_stream *stream,
>>>>
>>>> DBG3("Consumer delete metadata stream %d", stream->wait_fd);
>>>>
>>>> - if (ht == NULL) {
>>>> - /* Means the stream was allocated but not successfully added */
>>>> - goto free_stream;
>>>> - }
>>>> -
>>>> - rcu_read_lock();
>>>> - iter.iter.node = &stream->waitfd_node.node;
>>>> - ret = lttng_ht_del(ht, &iter);
>>>> - assert(!ret);
>>>> - rcu_read_unlock();
>>>> -
>>>> pthread_mutex_lock(&consumer_data.lock);
>>>> switch (consumer_data.type) {
>>>> case LTTNG_CONSUMER_KERNEL:
>>>> @@ -1613,6 +1587,18 @@ void consumer_del_metadata_stream(struct lttng_consumer_stream *stream,
>>>> goto end;
>>>> }
>>>>
>>>> + if (ht == NULL) {
>>>> + pthread_mutex_unlock(&consumer_data.lock);
>>>> + /* Means the stream was allocated but not successfully added */
>>>> + goto free_stream;
>>>> + }
>>>> +
>>>> + rcu_read_lock();
>>>> + iter.iter.node = &stream->waitfd_node.node;
>>>> + ret = lttng_ht_del(ht, &iter);
>>>> + assert(!ret);
>>>> + rcu_read_unlock();
>>>> +
>>>> if (stream->out_fd >= 0) {
>>>> ret = close(stream->out_fd);
>>>> if (ret) {
>>>> @@ -1699,27 +1685,6 @@ static int consumer_add_metadata_stream(struct lttng_consumer_stream *stream,
>>>>
>>>> pthread_mutex_lock(&consumer_data.lock);
>>>>
>>>> - switch (consumer_data.type) {
>>>> - case LTTNG_CONSUMER_KERNEL:
>>>> - break;
>>>> - case LTTNG_CONSUMER32_UST:
>>>> - case LTTNG_CONSUMER64_UST:
>>>> - ret = lttng_ustconsumer_add_stream(stream);
>>>> - if (ret) {
>>>> - ret = -EINVAL;
>>>> - goto error;
>>>> - }
>>>> -
>>>> - /* Steal stream identifier only for UST */
>>>> - consumer_steal_stream_key(stream->wait_fd, ht);
>>>> - break;
>>>> - default:
>>>> - ERR("Unknown consumer_data type");
>>>> - assert(0);
>>>> - ret = -ENOSYS;
>>>> - goto error;
>>>> - }
>>>> -
>>>> /*
>>>> * From here, refcounts are updated so be _careful_ when returning an error
>>>> * after this point.
>>>> @@ -1749,7 +1714,6 @@ static int consumer_add_metadata_stream(struct lttng_consumer_stream *stream,
>>>> lttng_ht_add_unique_ulong(ht, &stream->waitfd_node);
>>>> rcu_read_unlock();
>>>>
>>>> -error:
>>>> pthread_mutex_unlock(&consumer_data.lock);
>>>> return ret;
>>>> }
>>>> @@ -1946,7 +1910,7 @@ void *consumer_thread_data_poll(void *data)
>>>> int num_rdy, num_hup, high_prio, ret, i;
>>>> struct pollfd *pollfd = NULL;
>>>> /* local view of the streams */
>>>> - struct lttng_consumer_stream **local_stream = NULL;
>>>> + struct lttng_consumer_stream **local_stream = NULL, *new_stream = NULL;
>>>> /* local view of consumer_data.fds_count */
>>>> int nb_fd = 0;
>>>> struct lttng_consumer_local_data *ctx = data;
>>>> @@ -2034,13 +1998,35 @@ void *consumer_thread_data_poll(void *data)
>>>> */
>>>> if (pollfd[nb_fd].revents & (POLLIN | POLLPRI)) {
>>>> size_t pipe_readlen;
>>>> - char tmp;
>>>>
>>>> DBG("consumer_poll_pipe wake up");
>>>> /* Consume 1 byte of pipe data */
>>>> do {
>>>> - pipe_readlen = read(ctx->consumer_poll_pipe[0], &tmp, 1);
>>>> + pipe_readlen = read(ctx->consumer_poll_pipe[0], &new_stream,
>>>> + sizeof(new_stream));
>>>> } while (pipe_readlen == -1 && errno == EINTR);
>>>> +
>>>> + /*
>>>> + * If the stream is NULL, just ignore it. It's also possible that
>>>> + * the sessiond poll thread changed the consumer_quit state and is
>>>> + * waking us up to test it.
>>>> + */
>>>> + if (new_stream == NULL) {
>>>> + continue;
>>>> + }
>>>> +
>>>> + ret = consumer_add_stream(new_stream);
>>>> + if (ret) {
>>>> + ERR("Consumer add stream %d failed. Continuing",
>>>> + new_stream->key);
>>>> + /*
>>>> + * At this point, if the add_stream fails, it is not in the
>>>> + * hash table thus passing the NULL value here.
>>>> + */
>>>> + consumer_del_stream(new_stream, NULL);
>>>> + }
>>>> +
>>>> + /* Continue to update the local streams and handle prio ones */
>>>> continue;
>>>> }
>>>>
>>>> @@ -2260,19 +2246,16 @@ end:
>>>> consumer_poll_timeout = LTTNG_CONSUMER_POLL_TIMEOUT;
>>>>
>>>> /*
>>>> - * Wake-up the other end by writing a null byte in the pipe
>>>> - * (non-blocking). Important note: Because writing into the
>>>> - * pipe is non-blocking (and therefore we allow dropping wakeup
>>>> - * data, as long as there is wakeup data present in the pipe
>>>> - * buffer to wake up the other end), the other end should
>>>> - * perform the following sequence for waiting:
>>>> - * 1) empty the pipe (reads).
>>>> - * 2) perform update operation.
>>>> - * 3) wait on the pipe (poll).
>>>> + * Notify the data poll thread to poll back again and test the
>>>> + * consumer_quit state to quit gracefully.
>>>> */
>>>> do {
>>>> - ret = write(ctx->consumer_poll_pipe[1], "", 1);
>>>> + struct lttng_consumer_stream *null_stream = NULL;
>>>> +
>>>> + ret = write(ctx->consumer_poll_pipe[1], &null_stream,
>>>> + sizeof(null_stream));
>>>> } while (ret < 0 && errno == EINTR);
>>>> +
>>>> rcu_unregister_thread();
>>>> return NULL;
>>>> }
>>>> diff --git a/src/common/consumer.h b/src/common/consumer.h
>>>> index 4b225e4..8e5891a 100644
>>>> --- a/src/common/consumer.h
>>>> +++ b/src/common/consumer.h
>>>> @@ -362,6 +362,7 @@ struct consumer_relayd_sock_pair *consumer_allocate_relayd_sock_pair(
>>>> struct consumer_relayd_sock_pair *consumer_find_relayd(int key);
>>>> int consumer_handle_stream_before_relayd(struct lttng_consumer_stream *stream,
>>>> size_t data_size);
>>>> +void consumer_steal_stream_key(int key, struct lttng_ht *ht);
>>>>
>>>> extern struct lttng_consumer_local_data *lttng_consumer_create(
>>>> enum lttng_consumer_type type,
>>>> diff --git a/src/common/kernel-consumer/kernel-consumer.c b/src/common/kernel-consumer/kernel-consumer.c
>>>> index 13cbe21..444f5e0 100644
>>>> --- a/src/common/kernel-consumer/kernel-consumer.c
>>>> +++ b/src/common/kernel-consumer/kernel-consumer.c
>>>> @@ -235,10 +235,12 @@ int lttng_kconsumer_recv_cmd(struct lttng_consumer_local_data *ctx,
>>>> consumer_del_stream(new_stream, NULL);
>>>> }
>>>> } else {
>>>> - ret = consumer_add_stream(new_stream);
>>>> - if (ret) {
>>>> - ERR("Consumer add stream %d failed. Continuing",
>>>> - new_stream->key);
>>>> + do {
>>>> + ret = write(ctx->consumer_poll_pipe[1], &new_stream,
>>>> + sizeof(new_stream));
>>>> + } while (ret < 0 && errno == EINTR);
>>>> + if (ret < 0) {
>>>> + PERROR("write data pipe");
>>>> consumer_del_stream(new_stream, NULL);
>>>> goto end_nosignal;
>>>> }
>>>> @@ -284,20 +286,6 @@ int lttng_kconsumer_recv_cmd(struct lttng_consumer_local_data *ctx,
>>>> goto end_nosignal;
>>>> }
>>>>
>>>> - /*
>>>> - * Wake-up the other end by writing a null byte in the pipe (non-blocking).
>>>> - * Important note: Because writing into the pipe is non-blocking (and
>>>> - * therefore we allow dropping wakeup data, as long as there is wakeup data
>>>> - * present in the pipe buffer to wake up the other end), the other end
>>>> - * should perform the following sequence for waiting:
>>>> - *
>>>> - * 1) empty the pipe (reads).
>>>> - * 2) perform update operation.
>>>> - * 3) wait on the pipe (poll).
>>>> - */
>>>> - do {
>>>> - ret = write(ctx->consumer_poll_pipe[1], "", 1);
>>>> - } while (ret < 0 && errno == EINTR);
>>>> end_nosignal:
>>>> rcu_read_unlock();
>>>>
>>>> diff --git a/src/common/ust-consumer/ust-consumer.c b/src/common/ust-consumer/ust-consumer.c
>>>> index 1170687..4ca4b84 100644
>>>> --- a/src/common/ust-consumer/ust-consumer.c
>>>> +++ b/src/common/ust-consumer/ust-consumer.c
>>>> @@ -224,6 +224,18 @@ int lttng_ustconsumer_recv_cmd(struct lttng_consumer_local_data *ctx,
>>>> goto end_nosignal;
>>>> }
>>>>
>>>> + /*
>>>> + * This needs to be done as soon as we can so we don't block the
>>>> + * application too long.
>>>> + */
>>>> + ret = lttng_ustconsumer_add_stream(new_stream);
>>>> + if (ret) {
>>>> + consumer_del_stream(new_stream, NULL);
>>>> + goto end_nosignal;
>>>> + }
>>>> + /* Steal stream identifier to avoid having streams with the same key */
>>>> + consumer_steal_stream_key(new_stream->key, consumer_data.stream_ht);
>>>> +
>>>> /* The stream is not metadata. Get relayd reference if exists. */
>>>> relayd = consumer_find_relayd(msg.u.stream.net_index);
>>>> if (relayd != NULL) {
>>>> @@ -265,14 +277,12 @@ int lttng_ustconsumer_recv_cmd(struct lttng_consumer_local_data *ctx,
>>>> goto end_nosignal;
>>>> }
>>>> } else {
>>>> - ret = consumer_add_stream(new_stream);
>>>> - if (ret) {
>>>> - ERR("Consumer add stream %d failed. Continuing",
>>>> - new_stream->key);
>>>> - /*
>>>> - * At this point, if the add_stream fails, it is not in the
>>>> - * hash table thus passing the NULL value here.
>>>> - */
>>>> + do {
>>>> + ret = write(ctx->consumer_poll_pipe[1], &new_stream,
>>>> + sizeof(new_stream));
>>>> + } while (ret < 0 && errno == EINTR);
>>>> + if (ret < 0) {
>>>> + PERROR("write data pipe");
>>>> consumer_del_stream(new_stream, NULL);
>>>> goto end_nosignal;
>>>> }
>>>> @@ -334,20 +344,6 @@ int lttng_ustconsumer_recv_cmd(struct lttng_consumer_local_data *ctx,
>>>> break;
>>>> }
>>>>
>>>> - /*
>>>> - * Wake-up the other end by writing a null byte in the pipe (non-blocking).
>>>> - * Important note: Because writing into the pipe is non-blocking (and
>>>> - * therefore we allow dropping wakeup data, as long as there is wakeup data
>>>> - * present in the pipe buffer to wake up the other end), the other end
>>>> - * should perform the following sequence for waiting:
>>>> - *
>>>> - * 1) empty the pipe (reads).
>>>> - * 2) perform update operation.
>>>> - * 3) wait on the pipe (poll).
>>>> - */
>>>> - do {
>>>> - ret = write(ctx->consumer_poll_pipe[1], "", 1);
>>>> - } while (ret < 0 && errno == EINTR);
>>>> end_nosignal:
>>>> rcu_read_unlock();
>>>>
>>>> --
>>>> 1.7.10.4
>>>>
>>>>
>>>> _______________________________________________
>>>> lttng-dev mailing list
>>>> lttng-dev at lists.lttng.org
>>>> http://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev
>>>
>
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