[lttng-dev] [PATCH v3 2/2] Implement base-address-state tracing
Woegerer, Paul
Paul_Woegerer at mentor.com
Tue Nov 19 09:41:37 EST 2013
On 11/18/2013 08:59 AM, Amit Margalit wrote:
> Hi,
>
> I understand, and I see two issue with this -
>
> 1. The application will still perform all the tracking, but when the
> event is to be generated, it will be checked and since it is
> disabled, will not be emitted.
> While the overhead of checking whether the event is enabled is
> indeed minimal, the overhead of tracking existing state, is not
> negligible - it includes code, data and CPU cycles.
> 2. I believe that the average user will simply want to use
> "enable-event -u -a" or similar, and should not care about later
> disabling these specific events.
>
>
> I believe this ought to be a compile-time option, and I don't mind if
> it defaults to "Enabled"...
How about an environment variable (e.g.
LTTNG_UST_WITHOUT_BADDR_STATEDUMP) that suppresses base address state
tracing.
Would that be of value to you ?
--
Best,
Paul
>
> What do you think?
>
> Amit Margalit
> IBM XIV - /Storage Reinvented/
> XIV-NAS Development Team
> Tel. 03-689-7774
> Fax. 03-689-7230
>
>
>
> From: Mathieu Desnoyers <mathieu.desnoyers at efficios.com>
> To: Amit Margalit/Israel/IBM at IBMIL
> Cc: lttng-dev at lists.lttng.org, Paul Woegerer
> <paul_woegerer at mentor.com>
> Date: 11/17/2013 04:02 PM
> Subject: Re: [lttng-dev] [PATCH v3 2/2] Implement
> base-address-state tracing
> ------------------------------------------------------------------------
>
>
>
> ------------------------------------------------------------------------
>
> *From: *"Amit Margalit" <AMITM at il.ibm.com>*
> To: *"Mathieu Desnoyers" <mathieu.desnoyers at efficios.com>*
> Cc: *lttng-dev at lists.lttng.org, "Paul Woegerer"
> <paul_woegerer at mentor.com>*
> Sent: *Sunday, November 17, 2013 4:36:19 AM*
> Subject: *Re: [lttng-dev] [PATCH v3 2/2] Implement base-address-state
> tracing
>
> I guess I missed something in the discussion - is this going to be
> active all the time, or can I disable it somehow?
>
> Maybe a command-line switch to turn this off?
>
> For me this is overhead that I don't need and don't want.
>
> You just have to not enable those new events if you don't care about
> them.
>
> Thanks,
>
> Mathieu
>
>
> Thanks,
>
> Amit Margalit
> IBM XIV - /Storage Reinvented/
> XIV-NAS Development Team
> Tel. 03-689-7774
> Fax. 03-689-7230
>
>
>
> From: Mathieu Desnoyers <mathieu.desnoyers at efficios.com>
> To: Paul Woegerer <paul_woegerer at mentor.com>
> Cc: lttng-dev at lists.lttng.org
> Date: 11/14/2013 09:30 PM
> Subject: Re: [lttng-dev] [PATCH v3 2/2] Implement
> base-address-state tracing
> ------------------------------------------------------------------------
>
>
>
> ----- Original Message -----
> > From: "Paul Woegerer" <paul_woegerer at mentor.com>
> > To: lttng-dev at lists.lttng.org, "mathieu desnoyers"
> <mathieu.desnoyers at efficios.com>
> > Sent: Thursday, November 14, 2013 1:39:49 PM
> > Subject: [PATCH v3 2/2] Implement base-address-state tracing
> >
> > Dump the base-address state (executable and shared objects) into session
> > on session-enable (per-session events).
>
> Merged, thanks !
>
> Mathieu
>
> >
> > Signed-off-by: Paul Woegerer <paul_woegerer at mentor.com>
> > ---
> > include/lttng/ust-tracepoint-event.h | 14 +++++++
> > liblttng-ust-baddr/Makefile.am | 4 +-
> > liblttng-ust-baddr/lttng-ust-baddr.c | 72
> > ++++++++++++++++++++++++++++++++
> > liblttng-ust-baddr/ust_baddr_statedump.c | 21 ++++++++++
> > liblttng-ust-baddr/ust_baddr_statedump.h | 60
> ++++++++++++++++++++++++++
> > liblttng-ust/lttng-events.c | 2 +
> > liblttng-ust/lttng-tracer-core.h | 3 ++
> > liblttng-ust/lttng-ust-comm.c | 60
> ++++++++++++++++++++++++++
> > 8 files changed, 235 insertions(+), 1 deletion(-)
> > create mode 100644 liblttng-ust-baddr/ust_baddr_statedump.c
> > create mode 100644 liblttng-ust-baddr/ust_baddr_statedump.h
> >
> > diff --git a/include/lttng/ust-tracepoint-event.h
> > b/include/lttng/ust-tracepoint-event.h
> > index bb3a05d..be58030 100644
> > --- a/include/lttng/ust-tracepoint-event.h
> > +++ b/include/lttng/ust-tracepoint-event.h
> > @@ -480,6 +480,18 @@ size_t
> > __event_get_align__##_provider##___##_name(_TP_ARGS_PROTO(_args)) \
> > #define TP_FIELDS(...) __VA_ARGS__
> >
> > /*
> > + * For state dump, check that "session" argument (mandatory)
> matches the
> > + * session this event belongs to. Ensures that we write state dump
> data only
> > + * into the started session, not into all sessions.
> > + */
> > +#undef _TP_SESSION_CHECK
> > +#ifdef TP_SESSION_CHECK
> > +#define _TP_SESSION_CHECK(session, csession) (session == csession)
> > +#else /* TP_SESSION_CHECK */
> > +#define _TP_SESSION_CHECK(session, csession) 1
> > +#endif /* TP_SESSION_CHECK */
> > +
> > +/*
> > * Using twice size for filter stack data to hold size and pointer for
> > * each field (worse case). For integers, max size required is 64-bit.
> > * Same for double-precision floats. Those fit within
> > @@ -506,6 +518,8 @@ void
> > __event_probe__##_provider##___##_name(_TP_ARGS_DATA_PROTO(_args))
> \
> >
>
> \
> > if (0)
>
> \
> > (void) __dynamic_len_idx;
> /* don't warn if unused */ \
> > + if (!_TP_SESSION_CHECK(session, __chan->session))
> \
> > + return;
>
> \
> > if
> (caa_unlikely(!CMM_ACCESS_ONCE(__chan->session->active)))
> \
> > return;
>
> \
> > if
> (caa_unlikely(!CMM_ACCESS_ONCE(__chan->enabled)))
> \
> > diff --git a/liblttng-ust-baddr/Makefile.am
> b/liblttng-ust-baddr/Makefile.am
> > index afa9489..0d3cf28 100644
> > --- a/liblttng-ust-baddr/Makefile.am
> > +++ b/liblttng-ust-baddr/Makefile.am
> > @@ -5,7 +5,9 @@ lib_LTLIBRARIES = liblttng-ust-baddr.la
> > liblttng_ust_baddr_la_SOURCES = \
> > lttng-ust-baddr.c \
> > ust_baddr.c \
> > - ust_baddr.h
> > + ust_baddr.h \
> > + ust_baddr_statedump.c \
> > + ust_baddr_statedump.h
> > liblttng_ust_baddr_la_LIBADD = \
> > -L$(top_builddir)/liblttng-ust/.libs \
> > -llttng-ust
> > diff --git a/liblttng-ust-baddr/lttng-ust-baddr.c
> > b/liblttng-ust-baddr/lttng-ust-baddr.c
> > index f24a171..a856965 100644
> > --- a/liblttng-ust-baddr/lttng-ust-baddr.c
> > +++ b/liblttng-ust-baddr/lttng-ust-baddr.c
> > @@ -34,6 +34,7 @@
> >
> > #define TRACEPOINT_DEFINE
> > #include "ust_baddr.h"
> > +#include "ust_baddr_statedump.h"
> >
> > int
> > lttng_ust_push_baddr(void *so_base, const char *so_name)
> > @@ -62,3 +63,74 @@ lttng_ust_pop_baddr(void *so_base)
> > tracepoint(ust_baddr, pop, so_base);
> > return 0;
> > }
> > +
> > +static int
> > +extract_soinfo_events(struct dl_phdr_info *info, size_t size, void
> *data)
> > +{
> > + int j;
> > + int num_loadable_segment = 0;
> > +
> > + for (j = 0; j < info->dlpi_phnum; j++) {
> > + char resolved_path[PATH_MAX];
> > + struct stat sostat;
> > + void *base_addr_ptr;
> > +
> > + if (info->dlpi_phdr[j].p_type !=
> PT_LOAD)
> > + continue;
> > +
> > + /* Calculate virtual memory
> address of the loadable segment */
> > + base_addr_ptr = (void *)
> info->dlpi_addr
> > + +
> info->dlpi_phdr[j].p_vaddr;
> > +
> > + num_loadable_segment += 1;
> > + if ((info->dlpi_name == NULL ||
> info->dlpi_name[0] == 0)
> > +
> && num_loadable_segment == 1) {
> > + /*
> > + * If the
> iterated element is the executable itself we
> > + * have to use
> Dl_info to determine its full path
> > + */
> > + Dl_info dl_info
> = { 0 };
> > + if
> (!dladdr(base_addr_ptr, &dl_info))
> > +
> return 0;
> > + if
> (!realpath(dl_info.dli_fname, resolved_path))
> > +
> return 0;
> > + } else {
> > + /*
> > + * For regular
> dl_phdr_info entries we have to check if
> > + * the path to
> the shared object really exists
> > + */
> > + if
> (!realpath(info->dlpi_name, resolved_path)) {
> > +
> /* Found vDSO, put the 'path' into brackets */
> > +
> snprintf(resolved_path, PATH_MAX - 1, "[%s]",
> > +
> info->dlpi_name);
> > + }
> > + }
> > +
> > + if (stat(resolved_path, &sostat)) {
> > + sostat.st_size = 0;
> > + sostat.st_mtime
> = -1;
> > + }
> > +
> > + tracepoint(ust_baddr_statedump,
> soinfo,
> > +
> (struct lttng_session *) data, base_addr_ptr,
> > +
> resolved_path, sostat.st_size, sostat.st_mtime);
> > +
> > + /*
> > + * We are only interested in the
> base address (lowest virtual
> > + * address associated with the
> memory image), skip the rest
> > + */
> > + break;
> > + }
> > + return 0;
> > +}
> > +
> > +int
> > +lttng_ust_baddr_statedump(struct lttng_session *session)
> > +{
> > + /*
> > + * Iterate through the list of currently loaded
> shared objects and
> > + * generate events for loadable segments using
> extract_soinfo_events
> > + */
> > + dl_iterate_phdr(extract_soinfo_events, session);
> > + return 0;
> > +}
> > diff --git a/liblttng-ust-baddr/ust_baddr_statedump.c
> > b/liblttng-ust-baddr/ust_baddr_statedump.c
> > new file mode 100644
> > index 0000000..75f74ca
> > --- /dev/null
> > +++ b/liblttng-ust-baddr/ust_baddr_statedump.c
> > @@ -0,0 +1,21 @@
> > +/*
> > + * Copyright (C) 2013 Paul Woegerer <paul_woegerer at mentor.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; either
> > + * version 2.1 of the License, or (at your option) any later version.
> > + *
> > + * 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
> > + */
> > +
> > +#define TRACEPOINT_CREATE_PROBES
> > +#define TP_SESSION_CHECK
> > +#include "ust_baddr_statedump.h"
> > diff --git a/liblttng-ust-baddr/ust_baddr_statedump.h
> > b/liblttng-ust-baddr/ust_baddr_statedump.h
> > new file mode 100644
> > index 0000000..77a9af4
> > --- /dev/null
> > +++ b/liblttng-ust-baddr/ust_baddr_statedump.h
> > @@ -0,0 +1,60 @@
> > +#undef TRACEPOINT_PROVIDER
> > +#define TRACEPOINT_PROVIDER ust_baddr_statedump
> > +
> > +#if !defined(_TRACEPOINT_UST_BADDR_STATEDUMP_H) ||
> > defined(TRACEPOINT_HEADER_MULTI_READ)
> > +#define _TRACEPOINT_UST_BADDR_STATEDUMP_H
> > +
> > +#ifdef __cplusplus
> > +extern "C" {
> > +#endif
> > +
> > +/*
> > + * Copyright (C) 2013 Paul Woegerer <paul_woegerer at mentor.com>
> > + *
> > + * Permission is hereby granted, free of charge, to any person
> obtaining a
> > copy
> > + * of this software and associated documentation files (the
> "Software"), to
> > deal
> > + * in the Software without restriction, including without
> limitation the
> > rights
> > + * to use, copy, modify, merge, publish, distribute, sublicense,
> and/or sell
> > + * copies of the Software, and to permit persons to whom the
> Software is
> > + * furnished to do so, subject to the following conditions:
> > + *
> > + * The above copyright notice and this permission notice shall be
> included
> > in
> > + * all copies or substantial portions of the Software.
> > + *
> > + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
> EXPRESS
> > OR
> > + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
> MERCHANTABILITY,
> > + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO
> EVENT SHALL
> > THE
> > + * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
> OTHER
> > + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
> ARISING
> > FROM,
> > + * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
> DEALINGS IN
> > THE
> > + * SOFTWARE.
> > + */
> > +
> > +#include <stdint.h>
> > +#include <unistd.h>
> > +#include <lttng/ust-events.h>
> > +
> > +#define LTTNG_UST_BADDR_STATEDUMP_PROVIDER
> > +#include <lttng/tracepoint.h>
> > +
> > +TRACEPOINT_EVENT(ust_baddr_statedump, soinfo,
> > + TP_ARGS(struct lttng_session *, session, void *,
> baddr, const char*,
> > sopath, int64_t, size, int64_t, mtime),
> > + TP_FIELDS(
> > + ctf_integer_hex(void *, baddr, baddr)
> > + ctf_string(sopath, sopath)
> > + ctf_integer(int64_t, size, size)
> > + ctf_integer(int64_t, mtime, mtime)
> > + )
> > +)
> > +
> > +#endif /* _TRACEPOINT_UST_BADDR_STATEDUMP_H */
> > +
> > +#undef TRACEPOINT_INCLUDE
> > +#define TRACEPOINT_INCLUDE "./ust_baddr_statedump.h"
> > +
> > +/* This part must be outside ifdef protection */
> > +#include <lttng/tracepoint-event.h>
> > +
> > +#ifdef __cplusplus
> > +}
> > +#endif
> > diff --git a/liblttng-ust/lttng-events.c b/liblttng-ust/lttng-events.c
> > index 26601a6..21e3639 100644
> > --- a/liblttng-ust/lttng-events.c
> > +++ b/liblttng-ust/lttng-events.c
> > @@ -293,6 +293,8 @@ int lttng_session_enable(struct lttng_session
> *session)
> > /* Set atomically the state to "active" */
> > CMM_ACCESS_ONCE(session->active) = 1;
> > CMM_ACCESS_ONCE(session->been_active) = 1;
> > +
> > + lttng_ust_sockinfo_session_enabled(session->owner,
> session);
> > end:
> > return ret;
> > }
> > diff --git a/liblttng-ust/lttng-tracer-core.h
> > b/liblttng-ust/lttng-tracer-core.h
> > index f643a7e..e7f549e 100644
> > --- a/liblttng-ust/lttng-tracer-core.h
> > +++ b/liblttng-ust/lttng-tracer-core.h
> > @@ -45,4 +45,7 @@ const char *lttng_ust_obj_get_name(int id);
> >
> > int lttng_get_notify_socket(void *owner);
> >
> > +void lttng_ust_sockinfo_session_enabled(void *owner,
> > + struct lttng_session
> *session_enabled);
> > +
> > #endif /* _LTTNG_TRACER_CORE_H */
> > diff --git a/liblttng-ust/lttng-ust-comm.c
> b/liblttng-ust/lttng-ust-comm.c
> > index a6e4ba3..6ef3006 100644
> > --- a/liblttng-ust/lttng-ust-comm.c
> > +++ b/liblttng-ust/lttng-ust-comm.c
> > @@ -34,6 +34,7 @@
> > #include <time.h>
> > #include <assert.h>
> > #include <signal.h>
> > +#include <dlfcn.h>
> > #include <urcu/uatomic.h>
> > #include <urcu/futex.h>
> > #include <urcu/compiler.h>
> > @@ -106,6 +107,7 @@ struct sock_info {
> >
> > char wait_shm_path[PATH_MAX];
> > char *wait_shm_mmap;
> > + struct lttng_session *session_enabled;
> > };
> >
> > /* Socket from app (connect) to session daemon (listen) for
> communication */
> > @@ -122,6 +124,8 @@ struct sock_info global_apps = {
> > .notify_socket = -1,
> >
> > .wait_shm_path = "/" LTTNG_UST_WAIT_FILENAME,
> > +
> > + .session_enabled = NULL,
> > };
> >
> > /* TODO: allow global_apps_sock_path override */
> > @@ -135,6 +139,8 @@ struct sock_info local_apps = {
> >
> > .socket = -1,
> > .notify_socket = -1,
> > +
> > + .session_enabled = NULL,
> > };
> >
> > static int wait_poll_fallback;
> > @@ -176,6 +182,7 @@ static const char *cmd_name_mapping[] = {
> >
> > static const char *str_timeout;
> > static int got_timeout_env;
> > +static void *ust_baddr_handle;
> >
> > extern void lttng_ring_buffer_client_overwrite_init(void);
> > extern void lttng_ring_buffer_client_overwrite_rt_init(void);
> > @@ -235,6 +242,39 @@ void print_cmd(int cmd, int handle)
> > }
> >
> > static
> > +void *lttng_ust_baddr_handle(void)
> > +{
> > + if (!ust_baddr_handle) {
> > + ust_baddr_handle = dlopen(
> > +
> "liblttng-ust-baddr.so.0", RTLD_NOW | RTLD_GLOBAL);
> > + if (ust_baddr_handle == NULL)
> > + ERR("%s",
> dlerror());
> > + }
> > + return ust_baddr_handle;
> > +}
> > +
> > +static
> > +int lttng_ust_baddr_statedump(struct lttng_session *session)
> > +{
> > + static
> > + int (*lttng_ust_baddr_init_fn)(struct
> lttng_session *);
> > +
> > + if (!lttng_ust_baddr_init_fn) {
> > + void *baddr_handle =
> lttng_ust_baddr_handle();
> > + if (baddr_handle) {
> > +
> lttng_ust_baddr_init_fn = dlsym(baddr_handle,
> > +
> "lttng_ust_baddr_statedump");
> > + if
> (lttng_ust_baddr_init_fn == NULL)
> > +
> ERR("%s", dlerror());
> > + }
> > + if (!lttng_ust_baddr_init_fn)
> > + return -1;
> > + }
> > +
> > + return lttng_ust_baddr_init_fn(session);
> > +}
> > +
> > +static
> > int setup_local_apps(void)
> > {
> > const char *home_dir;
> > @@ -1143,6 +1183,13 @@ restart:
> > ret =
> handle_message(sock_info, sock, &lum);
> > if (ret) {
> >
> ERR("Error handling message for %s socket", sock_info->name);
> > + } else {
> > +
> struct lttng_session *session =
> > +
> sock_info->session_enabled;
> > +
> if (session) {
> > +
> sock_info->session_enabled = NULL;
> > +
> lttng_ust_baddr_statedump(session);
> > + }
> > }
> > continue;
> > default:
> > @@ -1379,6 +1426,12 @@ void __attribute__((destructor))
> lttng_ust_exit(void)
> > * cleanup the threads if there are stalled in a
> syscall.
> > */
> > lttng_ust_cleanup(1);
> > +
> > + if (ust_baddr_handle) {
> > + int ret = dlclose(ust_baddr_handle);
> > + if (ret)
> > + ERR("%s",
> dlerror());
> > + }
> > }
> >
> > /*
> > @@ -1456,3 +1509,10 @@ void ust_after_fork_child(sigset_t
> *restore_sigset)
> > ust_after_fork_common(restore_sigset);
> > lttng_ust_init();
> > }
> > +
> > +void lttng_ust_sockinfo_session_enabled(void *owner,
> > + struct lttng_session
> *session_enabled)
> > +{
> > + struct sock_info *sock_info = owner;
> > + sock_info->session_enabled = session_enabled;
> > +}
> > --
> > 1.8.4.2
> >
> >
>
> --
> Mathieu Desnoyers
> EfficiOS Inc._
> __http://www.efficios.com_ <http://www.efficios.com/>
>
> _______________________________________________
> lttng-dev mailing list
> lttng-dev at lists.lttng.org_
> __http://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev_
>
>
>
>
>
> --
> Mathieu Desnoyers
> EfficiOS Inc.
> http://www.efficios.com <http://www.efficios.com/>
--
Paul Woegerer, SW Development Engineer
Sourcery Analyzer <http://go.mentor.com/sourceryanalyzer>
Mentor Graphics, Embedded Software Division
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