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Tue, 30 Jun 2020 09:05:58 +0000 (UTC) Date: Tue, 30 Jun 2020 10:05:56 +0100 From: "Dr. David Alan Gilbert" To: Christophe de Dinechin Subject: Re: [PATCH v2 2/3] trace: Add support for recorder back-end Message-ID: <20200630090556.GA2673@work-vm> References: <20200626162706.3304357-1-dinechin@redhat.com> <20200626162706.3304357-3-dinechin@redhat.com> MIME-Version: 1.0 In-Reply-To: <20200626162706.3304357-3-dinechin@redhat.com> User-Agent: Mutt/1.14.3 (2020-06-14) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=dgilbert@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Received-SPF: pass client-ip=205.139.110.61; envelope-from=dgilbert@redhat.com; helo=us-smtp-delivery-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/06/30 01:11:03 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -30 X-Spam_score: -3.1 X-Spam_bar: --- X-Spam_report: (-3.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H3=-0.01, RCVD_IN_MSPIKE_WL=-0.01, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, URIBL_BLOCKED=0.001 autolearn=_AUTOLEARN X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Markus Armbruster , Michael Tokarev , qemu-devel@nongnu.org, Stefan Hajnoczi , Laurent Vivier Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" * Christophe de Dinechin (dinechin@redhat.com) wrote: > 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. > > Recorder support in qemu is implemented using the existing tracing > interface. In addition, it is possible to individually enable > recorders that are not traces, although this is probably not > recommended. > > 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 ^^^^^^^^ is that intended? > - 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 | 5 +++ > hmp-commands.hx | 19 ++++++++-- > monitor/misc.c | 27 ++++++++++++++ > scripts/tracetool/backend/recorder.py | 51 +++++++++++++++++++++++++++ > trace/Makefile.objs | 2 ++ > trace/control.c | 7 ++++ > trace/recorder.c | 22 ++++++++++++ > trace/recorder.h | 34 ++++++++++++++++++ > util/module.c | 8 +++++ > 9 files changed, 173 insertions(+), 2 deletions(-) > 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 ae8737d5a2..130630b98f 100755 > --- a/configure > +++ b/configure > @@ -7702,6 +7702,11 @@ fi > if have_backend "log"; then > echo "CONFIG_TRACE_LOG=y" >> $config_host_mak > fi > +if have_backend "recorder"; then > + echo "CONFIG_TRACE_RECORDER=y" >> $config_host_mak > + # This is a bit brutal, but there is currently a bug in the makefiles > + LIBS="$LIBS -lrecorder" > +fi > if have_backend "ust"; then > echo "CONFIG_TRACE_UST=y" >> $config_host_mak > fi > diff --git a/hmp-commands.hx b/hmp-commands.hx > index 60f395c276..565f518d4b 100644 > --- a/hmp-commands.hx > +++ b/hmp-commands.hx > @@ -297,6 +297,22 @@ ERST > .cmd = hmp_trace_file, > }, > > +SRST > +``trace-file on|off|flush`` > + 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 = "recorder", > + .args_type = "op:s?,arg:F?", Having 'arg' as a filename is a bit odd; using op/arg is very generic for adding extra commands; but it suddenly becomes less generic if arg is always a filename. > + .params = "trace|dump [arg]", > + .help = "trace selected recorders or print recorder dump", > + .cmd = hmp_recorder, > + }, > + > SRST > ``trace-file on|off|flush`` > Open, close, or flush the trace file. If no argument is given, the I think this SRST chunk is the one that needs updating for recorder. (The diff has made a bit of a mess, but I think you've copy pasted the trace-file chunk, but forgotten to update the SRST section). > @@ -1120,7 +1136,7 @@ ERST > > SRST > ``dump-guest-memory [-p]`` *filename* *begin* *length* > - \ > + \ > ``dump-guest-memory [-z|-l|-s|-w]`` *filename* > Dump guest memory to *protocol*. The file can be processed with crash or > gdb. Without ``-z|-l|-s|-w``, the dump format is ELF. > @@ -1828,4 +1844,3 @@ ERST > .sub_table = hmp_info_cmds, > .flags = "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 > > +#ifdef CONFIG_TRACE_RECORDER > +static void hmp_recorder(Monitor *mon, const QDict *qdict) > +{ > + const char *op = qdict_get_try_str(qdict, "op"); > + const char *arg = 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"); > + } > +} Consider whether just doing two separate commands would be easier; a recorder-trace and recorder-dump for example; that's fine from a HMP point of view and I think you'll find it's less code. Dave > +#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/backend/recorder.py > new file mode 100644 > index 0000000000..79cc6f5b03 > --- /dev/null > +++ b/scripts/tracetool/backend/recorder.py > @@ -0,0 +1,51 @@ > +# -*- coding: utf-8 -*- > + > +""" > +Trace back-end for recorder library > +""" > + > +__author__ = "Christophe de Dinechin " > +__copyright__ = "Copyright 2020, Christophe de Dinechin and Red Hat" > +__license__ = "GPL version 2 or (at your option) any later version" > + > +__maintainer__ = "Christophe de Dinechin" > +__email__ = "christophe@dinechin.org" > + > + > +from tracetool import out > + > +PUBLIC = True > + > +def generate_h_begin(events, group): > + out('#include ', '') > + > + for event in events: > + out('RECORDER_DECLARE(%(name)s);', name=event.name) > + > + > +def generate_h(event, group): > + argnames = ", ".join(event.args.names()) > + if len(event.args) > 0: > + argnames = ", " + argnames > + > + out(' record(%(event)s, %(fmt)s %(argnames)s);', > + event=event.name, > + fmt=event.fmt.rstrip("\n"), > + argnames=argnames) > + > + > +def generate_h_backend_dstate(event, group): > + out(' RECORDER_TWEAK(%(event_id)s) || \\', event_id=event.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=event.name, > + api=event.api(), > + args=event.args) > diff --git a/trace/Makefile.objs b/trace/Makefile.objs > index c544509adf..9e347640c2 100644 > --- a/trace/Makefile.objs > +++ b/trace/Makefile.objs > @@ -54,6 +54,8 @@ $(obj)/generated-tcg-tracers.h-timestamp: $(SRC_PATH)/trace-events $(BUILD_DIR)/ > > util-obj-$(CONFIG_TRACE_SIMPLE) += simple.o > util-obj-$(CONFIG_TRACE_FTRACE) += ftrace.o > +util-obj-$(CONFIG_TRACE_RECORDER) += recorder.o > +recorder.o-libs = -lrecorder > util-obj-y += control.o > obj-y += control-target.o > util-obj-y += 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 > > +#ifdef CONFIG_TRACE_RECORDER > + recorder_trace_init(); > +#endif > + > return true; > } > > diff --git a/trace/recorder.c b/trace/recorder.c > new file mode 100644 > index 0000000000..cbc22ee2d5 > --- /dev/null > +++ b/trace/recorder.c > @@ -0,0 +1,22 @@ > +/* > + * 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 "trace/recorder.h" > + > +RECORDER_CONSTRUCTOR > +void recorder_trace_init(void) > +{ > + recorder_trace_set(getenv("RECORDER_TRACES")); > + > + // Allow a dump in case we receive some unhandled signal > + // For example, send USR2 to a hung process to get a dump > + if (getenv("RECORDER_TRACES")) > + recorder_dump_on_common_signals(0,0); > +} > diff --git a/trace/recorder.h b/trace/recorder.h > new file mode 100644 > index 0000000000..00b11a2d2f > --- /dev/null > +++ b/trace/recorder.h > @@ -0,0 +1,34 @@ > +/* > + * 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 > + > +#include "qemu/osdep.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 > + > > typedef struct ModuleEntry > { > @@ -150,6 +154,10 @@ static int module_load_file(const char *fname) > g_module_close(g_module); > ret = -EINVAL; > } else { > +#ifdef CONFIG_TRACE_RECORDER > + // New recorders may have been pulled in, activate them if necessary > + recorder_trace_init(); > +#endif > QTAILQ_FOREACH(e, &dso_init_list, node) { > e->init(); > register_module_init(e->init, e->type); > -- > 2.26.2 > -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK