[lttng-dev] [PATCH v3 2/2] Implement base-address-state tracing
Amit Margalit
AMITM at il.ibm.com
Mon Nov 18 02:59:41 EST 2013
Hi,
I understand, and I see two issue with this -
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.
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"...
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
_______________________________________________
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
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