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bh=odDLa6KsxvuskxWO7HBlkhbdU2fzAGQo4bSupCSccbE=; b=Q/TiRBNKQstFkXEyqUc5jNSelBZre33yxt97Mn68SlDSvXJySYcypdE9SNXaBxN+KW5tQW FMkwp5pp3Ne3EnUY1PAL87snAOv/bGdRe3t58PPfkISat0Pv7tRGDx7hDjkA77UsfxyaYA P8hoYCmJ84bIUOtiN8LvkK399KVrNXE= X-MC-Unique: F_6mddp0OV-dtqE56ThLrw-1 From: Christophe de Dinechin To: qemu-devel@nongnu.org Subject: [PATCH v3 1/2] trace: Add support for recorder back-end Date: Mon, 6 Jul 2020 19:02:54 +0200 Message-Id: <20200706170255.1165105-2-dinechin@redhat.com> In-Reply-To: <20200706170255.1165105-1-dinechin@redhat.com> References: <20200706170255.1165105-1-dinechin@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=dinechin@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; 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charset="utf-8" The recorder library provides support for low-cost continuous recording of events, which can then be replayed. This makes it possible to collect data after the fact, for example to show the events that led to a crash or unexpected condition. In this series, minimal recorder support in qemu is implemented using the existing tracing interface. For each trace, a corresponding recorder is created with a generic name and a default size of 8 entries. In addition, it is possible to explicitly enable recorders that are not qemu traces, for example in order to use actually record events rather than trace them, or to use the real-time graphing capabilities. For that reason, a limited set of recorder-related macros are defined as no-ops even if the recorder trace backend is not configured. Recorder-specific features, notably the ability to perform a post-mortem dump and to group traces by topic, are not integrated in this series, as doing so would require modifying the trace infrastructure, which is a non-objective here. This may be the topic of later series if there is any interest for it. HMP COMMAND: The 'recorder' hmp command has been added, which supports two sub-commands: * recorder dump: Dump the current state of the recorder. You can give that command a recorder name, to only dump that recorder. * recorder trace: Set traces using the recorder_trace_set() syntax. You can use "recorder trace help" to list all available recorders. Signed-off-by: Christophe de Dinechin --- configure | 14 ++++++++ hmp-commands.hx | 23 +++++++++++- monitor/misc.c | 27 ++++++++++++++ scripts/tracetool/backend/recorder.py | 52 +++++++++++++++++++++++++++ trace/Makefile.objs | 1 + trace/control.c | 7 ++++ trace/recorder.c | 25 +++++++++++++ trace/recorder.h | 32 +++++++++++++++++ util/module.c | 8 +++++ 9 files changed, 188 insertions(+), 1 deletion(-) create mode 100644 scripts/tracetool/backend/recorder.py create mode 100644 trace/recorder.c create mode 100644 trace/recorder.h diff --git a/configure b/configure index 8a65240d4a..3c30f2defd 100755 --- a/configure +++ b/configure @@ -7727,6 +7727,20 @@ fi if have_backend "log"; then echo "CONFIG_TRACE_LOG=3Dy" >> $config_host_mak fi +if have_backend "recorder"; then + recorder_minver=3D"1.0.10" + if $pkg_config --atleast-version=3D$recorder_minver recorder ; then + recorder_cflags=3D"$($pkg_config --cflags recorder)" + recorder_libs=3D"$($pkg_config --libs recorder)" + LIBS=3D"$recorder_libs $LIBS" + libs_qga=3D"$recorder_libs $libs_qga" + QEMU_CFLAGS=3D"$QEMU_CFLAGS $recorder_cflags" + zstd=3D"yes" + echo "CONFIG_TRACE_RECORDER=3Dy" >> $config_host_mak + else + feature_not_found "recorder" "Install recorder-devel package" + fi +fi if have_backend "ust"; then echo "CONFIG_TRACE_UST=3Dy" >> $config_host_mak fi diff --git a/hmp-commands.hx b/hmp-commands.hx index d548a3ab74..f164ff6d65 100644 --- a/hmp-commands.hx +++ b/hmp-commands.hx @@ -302,6 +302,28 @@ SRST Open, close, or flush the trace file. If no argument is given, the status of the trace file is displayed. ERST +#endif + +#if defined(CONFIG_TRACE_RECORDER) + { + .name =3D "recorder", + .args_type =3D "op:s?,arg:s?", + .params =3D "trace|dump [arg]", + .help =3D "trace selected recorders or print recorder dump", + .cmd =3D hmp_recorder, + }, + +SRST +``trace`` *cmds* + Activate or deactivate tracing for individual recorder traces. + See recorder_trace_set(3) for the syntax of *cmds* + For example, to activate trace ``foo`` and disable alll traces + ending in ``_warning``, use ``foo:.*_warning=3D0``. + Using ``help`` will list available traces and their current setting. +``dump`` [*name*] + Dump the recorder. If *name* is given, only the specific named recorder + will be dumped. +ERST #endif =20 { @@ -1828,4 +1850,3 @@ ERST .sub_table =3D hmp_info_cmds, .flags =3D "p", }, - diff --git a/monitor/misc.c b/monitor/misc.c index 89bb970b00..0094b1860f 100644 --- a/monitor/misc.c +++ b/monitor/misc.c @@ -61,6 +61,9 @@ #ifdef CONFIG_TRACE_SIMPLE #include "trace/simple.h" #endif +#ifdef CONFIG_TRACE_RECORDER +#include "trace/recorder.h" +#endif #include "exec/memory.h" #include "exec/exec-all.h" #include "qemu/option.h" @@ -227,6 +230,30 @@ static void hmp_trace_file(Monitor *mon, const QDict *= qdict) } #endif =20 +#ifdef CONFIG_TRACE_RECORDER +static void hmp_recorder(Monitor *mon, const QDict *qdict) +{ + const char *op =3D qdict_get_try_str(qdict, "op"); + const char *arg =3D qdict_get_try_str(qdict, "arg"); + + if (!op) { + monitor_printf(mon, "missing recorder command\"%s\"\n", op); + help_cmd(mon, "recorder"); + } else if (!strcmp(op, "trace")) { + recorder_trace_set(arg); + } else if (!strcmp(op, "dump")) { + if (!arg || !*arg) { + recorder_dump(); + } else { + recorder_dump_for(arg); + } + } else { + monitor_printf(mon, "unexpected recorder command \"%s\"\n", op); + help_cmd(mon, "recorder"); + } +} +#endif + static void hmp_info_help(Monitor *mon, const QDict *qdict) { help_cmd(mon, "info"); diff --git a/scripts/tracetool/backend/recorder.py b/scripts/tracetool/back= end/recorder.py new file mode 100644 index 0000000000..82d983ff31 --- /dev/null +++ b/scripts/tracetool/backend/recorder.py @@ -0,0 +1,52 @@ +# -*- coding: utf-8 -*- + +""" +Trace back-end for recorder library +""" + +__author__ =3D "Christophe de Dinechin " +__copyright__ =3D "Copyright 2020, Christophe de Dinechin and Red Hat" +__license__ =3D "GPL version 2 or (at your option) any later version" + +__maintainer__ =3D "Christophe de Dinechin" +__email__ =3D "christophe@dinechin.org" + + +from tracetool import out + +PUBLIC =3D True + +def generate_h_begin(events, group): + out('#include ', '') + + for event in events: + out('RECORDER_DECLARE(%(name)s);', name=3Devent.name) + + +def generate_h(event, group): + argnames =3D ", ".join(event.args.names()) + if len(event.args) > 0: + argnames =3D ", " + argnames + + out(' record(%(event)s, %(fmt)s %(argnames)s);', + event=3Devent.name, + fmt=3Devent.fmt.rstrip("\n"), + argnames=3Dargnames) + + +def generate_h_backend_dstate(event, group): + out(' RECORDER_TWEAK(%(event_id)s) || \\', event_id=3Devent.name) + +def generate_c_begin(events, group): + out('#include "qemu/osdep.h"', + '#include "trace/control.h"', + '#include "trace/simple.h"', + '#include ', + '') + + for event in events: + out('RECORDER_DEFINE(%(name)s, 8,', + ' "Tracetool recorder for %(api)s(%(args)s)");', + name=3Devent.name, + api=3Devent.api(), + args=3Devent.args) diff --git a/trace/Makefile.objs b/trace/Makefile.objs index c544509adf..13667e98d5 100644 --- a/trace/Makefile.objs +++ b/trace/Makefile.objs @@ -54,6 +54,7 @@ $(obj)/generated-tcg-tracers.h-timestamp: $(SRC_PATH)/tra= ce-events $(BUILD_DIR)/ =20 util-obj-$(CONFIG_TRACE_SIMPLE) +=3D simple.o util-obj-$(CONFIG_TRACE_FTRACE) +=3D ftrace.o +util-obj-$(CONFIG_TRACE_RECORDER) +=3D recorder.o util-obj-y +=3D control.o obj-y +=3D control-target.o util-obj-y +=3D qmp.o diff --git a/trace/control.c b/trace/control.c index 2ffe000818..15e5293eec 100644 --- a/trace/control.c +++ b/trace/control.c @@ -23,6 +23,9 @@ #ifdef CONFIG_TRACE_SYSLOG #include #endif +#ifdef CONFIG_TRACE_RECORDER +#include "trace/recorder.h" +#endif #include "qapi/error.h" #include "qemu/error-report.h" #include "qemu/config-file.h" @@ -282,6 +285,10 @@ bool trace_init_backends(void) openlog(NULL, LOG_PID, LOG_DAEMON); #endif =20 +#ifdef CONFIG_TRACE_RECORDER + recorder_trace_init(); +#endif + return true; } =20 diff --git a/trace/recorder.c b/trace/recorder.c new file mode 100644 index 0000000000..e1859c2cf2 --- /dev/null +++ b/trace/recorder.c @@ -0,0 +1,25 @@ +/* + * Recorder-based trace backend + * + * Copyright Red Hat 2020 + * + * This work is licensed under the terms of the GNU GPL, version 2. See + * the COPYING file in the top-level directory. + * + */ + +#include "qemu/osdep.h" +#include "trace/recorder.h" + +RECORDER_CONSTRUCTOR +void recorder_trace_init(void) +{ + const char *traces =3D getenv("RECORDER_TRACES"); + recorder_trace_set(traces); + + /* Allow a dump in case we receive some unhandled signal + For example, send USR2 to a hung process to get a dump */ + if (traces) { + recorder_dump_on_common_signals(0, 0); + } +} diff --git a/trace/recorder.h b/trace/recorder.h new file mode 100644 index 0000000000..a531dc284a --- /dev/null +++ b/trace/recorder.h @@ -0,0 +1,32 @@ +/* + * Recorder-based trace backend + * + * Copyright Red Hat 2020 + * + * This work is licensed under the terms of the GNU GPL, version 2. See + * the COPYING file in the top-level directory. + * + */ + +#ifndef TRACE_RECORDER_H +#define TRACE_RECORDER_H + +#ifdef CONFIG_TRACE_RECORDER + +#include + +extern void recorder_trace_init(void); + +#else + +/* Disable recorder macros */ +#define RECORDER(Name, Size, Description) +#define RECORDER_DEFINE(Name, Size, Description) +#define RECORDER_DECLARE(Name) +#define RECORD(Name, ...) +#define record(Name, ...) +#define recorder_trace_init() + +#endif /* CONFIG_TRACE_RECORDER */ + +#endif // TRACE_RECORDER_H diff --git a/util/module.c b/util/module.c index e48d9aacc0..2fa93561fe 100644 --- a/util/module.c +++ b/util/module.c @@ -22,6 +22,10 @@ #ifdef CONFIG_MODULE_UPGRADES #include "qemu-version.h" #endif +#ifdef CONFIG_TRACE_RECORDER +#include "trace/recorder.h" +#endif + =20 typedef struct ModuleEntry { @@ -150,6 +154,10 @@ static int module_load_file(const char *fname) g_module_close(g_module); ret =3D -EINVAL; } else { +#ifdef CONFIG_TRACE_RECORDER + // New recorders may have been pulled in, activate them if necessa= ry + recorder_trace_init(); 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charset="utf-8" This patch is a simple example showing how the recorder can be used to have one "topic" covering multiple entries. Here, the topic is "lock", the idea being to have the latest lock changes for instance in case of a crash or hang. Here are a few use cases: * Tracing lock updates: RECORDER_TRACES=3Dlock qemu * Showing lock changes prior to a hang RECORDER_TRACES=3Dlock qemu & # Wait until hang killall -USR2 qemu # This will trigger a dump * Graphic visualization of lock states: RECORDER_TRACES=3D"lock=3Dstate,id" qemu & recorder_scope state # Hit the 't' key to toggle timing display # Hit the 'c' key to dump the screen data as CSV cat recorder_scope_data-1.csv Signed-off-by: Christophe de Dinechin --- util/qemu-thread-common.h | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/util/qemu-thread-common.h b/util/qemu-thread-common.h index 2af6b12085..0de07a471f 100644 --- a/util/qemu-thread-common.h +++ b/util/qemu-thread-common.h @@ -15,6 +15,9 @@ =20 #include "qemu/thread.h" #include "trace.h" +#include "trace/recorder.h" + +RECORDER_DEFINE(lock, 16, "Lock state"); =20 static inline void qemu_mutex_post_init(QemuMutex *mutex) { @@ -23,12 +26,14 @@ static inline void qemu_mutex_post_init(QemuMutex *mute= x) mutex->line =3D 0; #endif mutex->initialized =3D true; + record(lock, "Init state %d for %p", -1, mutex); } =20 static inline void qemu_mutex_pre_lock(QemuMutex *mutex, const char *file, int line) { trace_qemu_mutex_lock(mutex, file, line); + record(lock, "Locking state %d for %p", 1, mutex); } =20 static inline void qemu_mutex_post_lock(QemuMutex *mutex, @@ -39,6 +44,7 @@ static inline void qemu_mutex_post_lock(QemuMutex *mutex, mutex->line =3D line; #endif trace_qemu_mutex_locked(mutex, file, line); + record(lock, "Locked state %d for %p", 2, mutex); } =20 static inline void qemu_mutex_pre_unlock(QemuMutex *mutex, @@ -49,6 +55,7 @@ static inline void qemu_mutex_pre_unlock(QemuMutex *mutex, mutex->line =3D 0; #endif trace_qemu_mutex_unlock(mutex, file, line); + record(lock, "Unkocked state %d for %p", 0, mutex); } =20 #endif --=20 2.26.2