[lttng-dev] [PATCH lttng-ust v2] Fix: allocate ts_end in ringbuffer shared memory
Mathieu Desnoyers
mathieu.desnoyers at efficios.com
Fri May 10 14:00:36 EDT 2019
----- On May 10, 2019, at 12:33 PM, Sebastien Boisvert sboisvert at gydle.com wrote:
> On 2019-05-10 11:26 a.m., Gabriel-Andrew Pollo-Guilbert wrote:
>
> Hello Gabriel-Andrew,
>
>> This patch allocates the memory used by the ts_end field added by commit
>> 6c737d05. When allocating lots of subbuffer for a channel (512 or more),
>> zalloc_shm() will fail to allocate all the objects because the allocated memory
>> map didn't take account the newly added field.
>>
>> lttng-tools version: b14f53d4 (2.12.0-pre)
>>
>> Steps to reproduce the bug:
>>
>> 1. lttng-sessiond -vvv --verbose-consumer
>
> I need to killall existing lttng-sessiond daemon, right ?
>
>> 2. start a traced application
>
> I used lttng-ust/doc/examples/demo/.
>
>> 3. lttng create "test-sesssion"
> ^^^
> There are too many s in session.
oops, already merged.
>
>
>> 4. lttng enable-channel --userspace --num-subbuf 512 --subbuf-size 8k
>> --overwrite channel
>> 5. lttng enable-event -u -a -c channel
>> 6. lttng start
>>
>> After these steps, the following error message show should be thrown:
>>
>> Error: ask_channel_creation consumer command failed
>> Error: Error creating UST channel "channel" on the consumer daemon
>
> When I build lttng-tools b14f53d4
>
> I get this error:
>
> make[3]: Entering directory
> '/home/sboisvert/open-source/lttng.org/Source/lttng-tools/src/common/ust-consumer'
> CC ust-consumer.lo
> ust-consumer.c: In function 'lttng_ustconsumer_recv_cmd':
> ust-consumer.c:1459:7: error: 'struct ustctl_consumer_channel_attr' has no
> member named 'blocking_timeout'
> attr.blocking_timeout= msg.u.ask_channel.blocking_timeout;
> ^
> ust-consumer.c: In function 'lttng_ustconsumer_sample_snapshot_positions':
> ust-consumer.c:2225:9: warning: implicit declaration of function
> 'ustctl_snapshot_sample_positions'; did you mean
> 'ustctl_snapshot_get_produced'? [-Wimplicit-function-declaration]
> return ustctl_snapshot_sample_positions(stream->ustream);
> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> ustctl_snapshot_get_produced
> Makefile:548: recipe for target 'ust-consumer.lo' failed
>
>
> There seems to be 2 declarations of struct ustctl_consumer_channel_attr.
>
> In file lttng-tools/src/bin/lttng-sessiond/lttng-ust-ctl.h,
> struct ustctl_consumer_channel_attr has the attribute blocking_timeout.
>
> In file lttng-ust/include/lttng/ust-ctl.h, struct ustctl_consumer_channel_attr
> does not have the attribute.
>
>
> They are exactly the same, except the missing blocking_timeout attribute.
>
>
> [sboisvert at GT480:Source]$ grep -A 10 "struct ustctl_consumer_channel_attr {"
> lttng-ust/include/lttng/ust-ctl.h
> struct ustctl_consumer_channel_attr {
> enum lttng_ust_chan_type type;
> uint64_t subbuf_size; /* bytes */
> uint64_t num_subbuf; /* power of 2 */
> int overwrite; /* 1: overwrite, 0: discard */
> unsigned int switch_timer_interval; /* usec */
> unsigned int read_timer_interval; /* usec */
> enum lttng_ust_output output; /* splice, mmap */
> uint32_t chan_id; /* channel ID */
> unsigned char uuid[LTTNG_UST_UUID_LEN]; /* Trace session unique ID */
> } LTTNG_PACKED;
>
> [sboisvert at GT480:Source]$ grep -A 11 "struct ustctl_consumer_channel_attr {"
> lttng-tools/src/bin/lttng-sessiond/lttng-ust-ctl.h
> struct ustctl_consumer_channel_attr {
> enum lttng_ust_chan_type type;
> uint64_t subbuf_size; /* bytes */
> uint64_t num_subbuf; /* power of 2 */
> int overwrite; /* 1: overwrite, 0: discard */
> unsigned int switch_timer_interval; /* usec */
> unsigned int read_timer_interval; /* usec */
> enum lttng_ust_output output; /* splice, mmap */
> uint32_t chan_id; /* channel ID */
> unsigned char uuid[LTTNG_UST_UUID_LEN]; /* Trace session unique ID */
> int64_t blocking_timeout; /* Blocking timeout (usec) */
> } LTTNG_PACKED;
>
> [sboisvert at GT480:Source]$ diff -u <(grep -A 11 "struct
> ustctl_consumer_channel_attr {"
> lttng-tools/src/bin/lttng-sessiond/lttng-ust-ctl.h) <(grep -A 10 "struct
> ustctl_consumer_channel_attr {" lttng-ust/include/lttng/ust-ctl.h)
> --- /dev/fd/63 2019-05-10 12:32:23.562246820 -0400
> +++ /dev/fd/62 2019-05-10 12:32:23.562246820 -0400
> @@ -8,5 +8,4 @@
> enum lttng_ust_output output; /* splice, mmap */
> uint32_t chan_id; /* channel ID */
> unsigned char uuid[LTTNG_UST_UUID_LEN]; /* Trace session unique ID */
> - int64_t blocking_timeout; /* Blocking timeout (usec) */
> } LTTNG_PACKED;
>
>
> My configure commands (followed by "make install"):
>
> [sboisvert at GT480:userspace-rcu]$ ./configure
> --prefix=/home/sboisvert/open-source/lttng.org/Build/userspace-rcu/v0.11.0
>
> [sboisvert at GT480:lttng-ust]$ ./configure
> --prefix=/home/sboisvert/open-source/lttng.org/Build/lttng-ust/v2.9.4
> LDFLAGS=-L/home/sboisvert/open-source/lttng.org/Build/userspace-rcu/v0.11.0/lib
I think you need a lttng-ust which is more recent than 2.9.4.
Thanks,
Mathieu
>
> [sboisvert at GT480:lttng-tools]$ ./configure
> --prefix=/home/sboisvert/open-source/lttng.org/Build/lttng-tools/b14f53d4
> LDFLAGS=-L/home/sboisvert/open-source/lttng.org/Build/lttng-ust/v2.9.4/lib
> CPPFLAGS=-I/home/sboisvert/open-source/lttng.org/Build/lttng-ust/v2.9.4/include
>
>
> Thanks
>
>>
>> Signed-off-by: Gabriel-Andrew Pollo-Guilbert
>> <gabriel.pollo-guilbert at efficios.com>
>> ---
>> libringbuffer/ring_buffer_backend.c | 3 +++
>> 1 file changed, 3 insertions(+)
>>
>> diff --git a/libringbuffer/ring_buffer_backend.c
>> b/libringbuffer/ring_buffer_backend.c
>> index a0ef7446..431b8eae 100644
>> --- a/libringbuffer/ring_buffer_backend.c
>> +++ b/libringbuffer/ring_buffer_backend.c
>> @@ -341,6 +341,9 @@ int channel_backend_init(struct channel_backend *chanb,
>> shmsize += sizeof(struct commit_counters_hot) * num_subbuf;
>> shmsize += offset_align(shmsize, __alignof__(struct commit_counters_cold));
>> shmsize += sizeof(struct commit_counters_cold) * num_subbuf;
>> + /* Sampled timestamp end */
>> + shmsize += offset_align(shmsize, __alignof__(uint64_t));
>> + shmsize += sizeof(uint64_t) * num_subbuf;
>>
>> if (config->alloc == RING_BUFFER_ALLOC_PER_CPU) {
>> struct lttng_ust_lib_ring_buffer *buf;
>>
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--
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com
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