[lttng-dev] [PATCH lttng-tools] Fix: Fail to add several perf_thread context

Mon Nov 3 16:30:16 EST 2014

Hi Jérémie,

"lttng add-context" should not fail when several unique performance
counters added after start program with tracepoints. Now "lttng add-context"
 fail when several unique perf_tread context added after start program with
tracepoints.

I wrote about this problem:

---------- Forwarded message ----------
From: Alexander Grigoriev <alexgri at tbricks.com>
Date: Tue, Sep 30, 2014 at 4:23 PM
Subject: Problem with perf:thread in 2.5
To: lttng-dev at lists.lttng.org

Hello,

I use lttng-2.5 and linux-3.8.13. When I try to add context with several
performance counters after start program with tracepoints, I get the
following error:

> app_with_lttng &  // { tracepoint(test, test, 1); sleep(1000); }
[1] 19297

> lttng destroy -a
No session found, nothing to do.

> lttng -vvv create test
DEBUG3 - 14:54:42.713573 [19313/19313]: URI string:
file:///home/alexgri/lttng-traces/test-20140930-145442 (in uri_parse() at
uri.c:293)
DEBUG3 - 14:54:42.713607 [19313/19313]: URI file destination:
/home/alexgri/lttng-traces/test-20140930-145442 (in uri_parse() at
uri.c:330)
DEBUG3 - 14:54:42.713616 [19313/19313]: URI dtype: 3, proto: 0, host: ,
subdir: , ctrl: 0, data: 0 (in uri_parse() at uri.c:507)
DEBUG1 - 14:54:42.713667 [19313/19313]: LSM cmd type : 8 (in
send_session_msg() at lttng-ctl.c:131)
Session test created.
Traces will be written in /home/alexgri/lttng-traces/test-20140930-145442
DEBUG1 - 14:54:42.715819 [19313/19313]: Init config session in
/home/alexgri (in config_init() at conf.c:295)

> lttng -vvv add-context -u -t vpid -t perf:thread:cpu-cycles -t
perf:thread:instructions -t perf:thread:cache-misses -s test
DEBUG1 - 14:54:52.124745 [19316/19316]: Adding context... (in add_context()
at commands/add_context.c:600)
DEBUG1 - 14:54:52.133393 [19316/19316]: LSM cmd type : 0 (in
send_session_msg() at lttng-ctl.c:131)
UST context vpid added to all channels
DEBUG1 - 14:54:52.153445 [19316/19316]: Adding context... (in add_context()
at commands/add_context.c:600)
DEBUG1 - 14:54:52.153499 [19316/19316]: LSM cmd type : 0 (in
send_session_msg() at lttng-ctl.c:131)
UST context perf:thread:cpu-cycles added to all channels
DEBUG1 - 14:54:52.154356 [19316/19316]: Adding context... (in add_context()
at commands/add_context.c:600)
DEBUG1 - 14:54:52.154392 [19316/19316]: LSM cmd type : 0 (in
send_session_msg() at lttng-ctl.c:131)
Error: perf:thread:instructions: UST context already exist
DEBUG1 - 14:54:52.154469 [19316/19316]: Adding context... (in add_context()
at commands/add_context.c:600)
DEBUG1 - 14:54:52.154525 [19316/19316]: LSM cmd type : 0 (in
send_session_msg() at lttng-ctl.c:131)
Error: perf:thread:cache-misses: UST context already exist
Warning: Some command(s) went wrong
DEBUG1 - 14:54:52.154620 [19316/19316]: Clean exit (in clean_exit() at
lttng.c:167)

'lttng-sessiond -vvv' logs in attachment

Thanks,
Alexander
---------------------------------------------------

Thanks,
Alexander

On Mon, Nov 3, 2014 at 11:28 PM, Jérémie Galarneau <
jeremie.galarneau at efficios.com> wrote:

> Hi Alexander,
>
> Just to make sure I understand the problem, is your point that "lttng
> add-context" should not fail when multiple contexts are added just
> because one of them was already present? If not, could you provide a
> log demonstrating the issue?
>
> Thanks!
> Jérémie
>
> On Sat, Nov 1, 2014 at 7:14 PM, Alexander Grigoriev <alexgri at tbricks.com>
> wrote:
> > In commit aa3514e96f12c13f681a81ea275dc51dd63473c8 not removed old check
> > for duplicate context type in create_ust_app_channel_context() function.
> If
> > the one of perf_tread contexts was already added, in the next
> > similar operation function returns error code EEXIST "UST context
> > already exist".
> >
> > Signed-off-by: Alexander Grigoriev <alexgri at tbricks.com>
> > ---
> >  src/bin/lttng-sessiond/ust-app.c | 7 -------
> >  1 file changed, 7 deletions(-)
> >
> > diff --git a/src/bin/lttng-sessiond/ust-app.c
> b/src/bin/lttng-sessiond/ust-app.c
> > index f8e9693..7f1594b 100644
> > --- a/src/bin/lttng-sessiond/ust-app.c
> > +++ b/src/bin/lttng-sessiond/ust-app.c
> > @@ -1940,13 +1940,6 @@ int create_ust_app_channel_context(struct
> ust_app_session *ua_sess,
> >
> >         DBG2("UST app adding context to channel %s", ua_chan->name);
> >
> > -       lttng_ht_lookup(ua_chan->ctx, (void *)((unsigned
> long)uctx->ctx), &iter);
> > -       node = lttng_ht_iter_get_node_ulong(&iter);
> > -       if (node != NULL) {
> > -               ret = -EEXIST;
> > -               goto error;
> > -       }
> > -
> >         ua_ctx = alloc_ust_app_ctx(uctx);
> >         if (ua_ctx == NULL) {
> >                 /* malloc failed */
> > --
> > 1.9.1
> >
> >
> > _______________________________________________
> > lttng-dev mailing list
> > lttng-dev at lists.lttng.org
> > http://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev
>
>
>
> --
> Jérémie Galarneau
> EfficiOS Inc.
> http://www.efficios.com
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.lttng.org/pipermail/lttng-dev/attachments/20141104/c42c5b68/attachment-0001.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: lttng-sessiond-vvv.log
Type: application/octet-stream
Size: 45327 bytes
Desc: not available
URL: <http://lists.lttng.org/pipermail/lttng-dev/attachments/20141104/c42c5b68/attachment-0001.obj>