[lttng-dev] [PATCH lttng-ust v2] Fix: allocate ts_end in ringbuffer shared memory
Jonathan Rajotte-Julien
jonathan.rajotte-julien at efficios.com
Fri May 10 14:16:26 EDT 2019
On Fri, May 10, 2019 at 02:08:51PM -0400, Jonathan Rajotte-Julien wrote:
> Hi,
>
> On Fri, May 10, 2019 at 12:33:42PM -0400, Sebastien Boisvert 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 ?
>
> No, since we are in userspace this can be done with a root lttng-sessiond
> present. But in real life -> yes.
>
> >
> > > 2. start a traced application
> >
> > I used lttng-ust/doc/examples/demo/.
>
> Make sure that the app is long lived (easy-ust with a while loop for example).
> This is only to force the allocation on lttng start.
>
> >
> > > 3. lttng create "test-sesssion"
> > ^^^
> > There are too many s in session.
>
> Does not matter since it is the session name here and subsequent call are done
> in the context on that session. Still a good catch.
>
> >
> >
> > > 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
>
> Are you sure you are building lttng-tools against lttng-ust
> 6c737d0594cac0d969e1948ea1ed55c15be9cec8 or master?
>
> In any case, this does not seems related to this particular issue. Please start
> a new email thread.
>
> >
> >
> > 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.
>
> Currently on 6c737d0594cac0d969e1948ea1ed55c15be9cec8 (almost master):
>
> 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;
>
> This field was introduced in b2c5f61a9. Suggesting that you lttng-ust tree is
> out of date.
>
> >
> >
> > 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
> >
> > [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
> >
>
> This is probably an artefact but all your path have 2.9 in them. This work is
> done against master of lttng-tools and lttng-ust.
>
> Our CI does not indicate any failure for the master branches. [1]
>
> [1]
A bit quick on the send email on that one.
Our ci currently indicate failure for the master branch but nothing during the
build process (at make check).
[1] https://ci.lttng.org/job/lttng-tools_master_build/
>
> Cheers
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--
Jonathan Rajotte-Julien
EfficiOS
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