[ovs-dev] [PATCH V5] Function tracer to trace all function calls
Daniele Di Proietto
diproiettod at ovn.org
Wed Jun 15 01:58:33 UTC 2016
Hi Nirapada,
When optimizing for the DPDK datapath we have a very similar problem and,
usually, running a simple profiler like perf (
https://perf.wiki.kernel.org/index.php/Main_Page) is enough to highlight
the bottlenecks in terms of CPU usage.
Have you tried perf? Does this infrastructure provide advantages over
sample profiling? I'm not saying that one is better than the other, I'm
just curious!
Thanks,
Daniele
2016-06-14 18:05 GMT-07:00 <nghosh at us.ibm.com>:
> In some circumstances, we might need to figure out where in
> code, the CPU time is being spent most, so as to pinpoint
> the bottleneck and thereby resolve it with proper changes.
> Using '-finstrument-functions' flag, that can be achieved, and
> this patch exactly does that.
>
> There is a python file [generate_ft_report.py] with the patch,
> that may be used to convert this trace output to a human readable
> format with symbol names instead of address and their execution
> times. This tool uses addr2line that expects the executable to
> be built with -g flag.
>
> To enable this feature, ovs needs needs to be configured with
> "--enable-ft" command line argument [i.e. configure --enable-ft]
>
> This instrumentation logs the tracing output in separate log files
> namely func_trace_<pid>.log. It does not use VLOG mechanism for
> logging as that will make the patch very complicated to avoid
> recursion in the trace routine.
>
> This feature starts dumping output, only in debug mode, which means
> ovs-appctl -t <module> vlog/set any:any:dbg should be used to enable
> this logging.
>
> Currently, only ovn-northd, ovn-controller, vswitchd are instrumented.
>
> It is intended to be used for debugging purposes.
> Signed-off-by: Nirapada Ghosh <nghosh at us.ibm.com>
>
> ---
> configure.ac | 10 +++
> include/openvswitch/vlog.h | 1 +
> lib/vlog.c | 23 ++++++-
> ovn/controller/automake.mk | 9 +++
> ovn/controller/ovn-controller.c | 9 +++
> ovn/northd/automake.mk | 9 +++
> ovn/northd/ovn-northd.c | 9 +++
> third-party/function_tracer.c | 126
> ++++++++++++++++++++++++++++++++++++++
> third-party/generate_ft_report.py | 80 ++++++++++++++++++++++++
> utilities/automake.mk | 1 +
> vswitchd/automake.mk | 8 +++
> vswitchd/ovs-vswitchd.c | 8 +++
> 12 files changed, 292 insertions(+), 1 deletion(-)
> create mode 100644 third-party/function_tracer.c
> create mode 100644 third-party/generate_ft_report.py
>
> diff --git a/configure.ac b/configure.ac
> index 05d80d5..4abb2ea 100644
> --- a/configure.ac
> +++ b/configure.ac
> @@ -28,6 +28,16 @@ AC_PROG_MKDIR_P
> AC_PROG_FGREP
> AC_PROG_EGREP
>
> +AC_ARG_ENABLE(ft,
> +[ --enable-ft Turn on function-tracing],
> +[case "${enableval}" in
> + yes) ft=true ;;
> + no) ft=false ;;
> + *) AC_MSG_ERROR(bad value ${enableval} for --enable-ft) ;;
> +esac],[ft=false])
> +AM_CONDITIONAL(ENABLE_FT, test x$ft = xtrue)
> +
> +
> AC_ARG_VAR([PERL], [path to Perl interpreter])
> AC_PATH_PROG([PERL], perl, no)
> if test "$PERL" = no; then
> diff --git a/include/openvswitch/vlog.h b/include/openvswitch/vlog.h
> index de64cbd..2df8796 100644
> --- a/include/openvswitch/vlog.h
> +++ b/include/openvswitch/vlog.h
> @@ -57,6 +57,7 @@ enum vlog_level {
> VLL_N_LEVELS
> };
>
> +void __attribute__ ((no_instrument_function)) vlog_directory(char *, int);
> const char *vlog_get_level_name(enum vlog_level);
> enum vlog_level vlog_get_level_val(const char *name);
>
> diff --git a/lib/vlog.c b/lib/vlog.c
> index 30b5bc2..65fa073 100644
> --- a/lib/vlog.c
> +++ b/lib/vlog.c
> @@ -1137,7 +1137,6 @@ vlog_valist(const struct vlog_module *module, enum
> vlog_level level,
> errno = save_errno;
> }
> }
> -
> void
> vlog(const struct vlog_module *module, enum vlog_level level,
> const char *message, ...)
> @@ -1262,6 +1261,28 @@ vlog_should_drop(const struct vlog_module *module,
> enum vlog_level level,
> return false;
> }
>
> +void __attribute__ ((no_instrument_function))
> +vlog_directory(char *dir,int len)
> +{
> + int dir_len;
> + if (log_file_name == NULL) {
> + dir_len = strlen(ovs_logdir());
> + if (dir_len > len) {
> + *dir = '\0';
> + }
> + snprintf(dir, dir_len, "%s", ovs_logdir());
> + } else {
> + char *fname = strrchr(log_file_name,'/');
> + if (fname) {
> + dir_len = strlen(log_file_name) - strlen(fname)+1;
> + if (dir_len > len) {
> + *dir = '\0';
> + } else {
> + snprintf(dir, dir_len, "%s", log_file_name);
> + }
> + }
> + }
> +}
> void
> vlog_rate_limit(const struct vlog_module *module, enum vlog_level level,
> struct vlog_rate_limit *rl, const char *message, ...)
> diff --git a/ovn/controller/automake.mk b/ovn/controller/automake.mk
> index cf57bbd..61efcf4 100644
> --- a/ovn/controller/automake.mk
> +++ b/ovn/controller/automake.mk
> @@ -1,3 +1,9 @@
> +if ENABLE_FT
> +CFLAGS += -g -finstrument-functions \
> + `pkg-config --cflags glib-2.0` \
> + `pkg-config --libs glib-2.0` -ldl -export-dynamic -lrt
> +endif
> +
> bin_PROGRAMS += ovn/controller/ovn-controller
> ovn_controller_ovn_controller_SOURCES = \
> ovn/controller/binding.c \
> @@ -20,6 +26,9 @@ ovn_controller_ovn_controller_SOURCES = \
> ovn/controller/ovn-controller.h \
> ovn/controller/physical.c \
> ovn/controller/physical.h
> +if ENABLE_FT
> +ovn_controller_ovn_controller_SOURCES += third-party/function_tracer.c
> +endif
> ovn_controller_ovn_controller_LDADD = ovn/lib/libovn.la lib/
> libopenvswitch.la
> man_MANS += ovn/controller/ovn-controller.8
> EXTRA_DIST += ovn/controller/ovn-controller.8.xml
> diff --git a/ovn/controller/ovn-controller.c
> b/ovn/controller/ovn-controller.c
> index 356a94b..4f71b15 100644
> --- a/ovn/controller/ovn-controller.c
> +++ b/ovn/controller/ovn-controller.c
> @@ -61,11 +61,19 @@ static unixctl_cb_func ct_zone_list;
>
> #define DEFAULT_BRIDGE_NAME "br-int"
>
> +static bool g_command_line_args_parsed = false;
> static void parse_options(int argc, char *argv[]);
> +
> OVS_NO_RETURN static void usage(void);
>
> static char *ovs_remote;
>
> +bool
> +is_command_line_args_parsed(void)
> +{
> + return g_command_line_args_parsed;
> +}
> +
> struct local_datapath *
> get_local_datapath(const struct hmap *local_datapaths, uint32_t
> tunnel_key)
> {
> @@ -614,6 +622,7 @@ parse_options(int argc, char *argv[])
> VLOG_FATAL("exactly zero or one non-option argument required; "
> "use --help for usage");
> }
> + g_command_line_args_parsed = true;
> }
>
> static void
> diff --git a/ovn/northd/automake.mk b/ovn/northd/automake.mk
> index 6e713fc..ae8dc3f 100644
> --- a/ovn/northd/automake.mk
> +++ b/ovn/northd/automake.mk
> @@ -1,6 +1,15 @@
> # ovn-northd
> +if ENABLE_FT
> +CFLAGS += -g -finstrument-functions \
> + `pkg-config --cflags glib-2.0` \
> + `pkg-config --libs glib-2.0` -ldl -export-dynamic -lrt
> +endif
> +
> bin_PROGRAMS += ovn/northd/ovn-northd
> ovn_northd_ovn_northd_SOURCES = ovn/northd/ovn-northd.c
> +if ENABLE_FT
> +ovn_northd_ovn_northd_SOURCES += third-party/function_tracer.c
> +endif
> ovn_northd_ovn_northd_LDADD = \
> ovn/lib/libovn.la \
> ovsdb/libovsdb.la \
> diff --git a/ovn/northd/ovn-northd.c b/ovn/northd/ovn-northd.c
> index d53fca9..6ffef96 100644
> --- a/ovn/northd/ovn-northd.c
> +++ b/ovn/northd/ovn-northd.c
> @@ -42,6 +42,8 @@
>
> VLOG_DEFINE_THIS_MODULE(ovn_northd);
>
> +static bool g_command_line_args_parsed = false;
> +
> static unixctl_cb_func ovn_northd_exit;
>
> struct northd_context {
> @@ -119,6 +121,12 @@ enum ovn_stage {
> #undef PIPELINE_STAGE
> };
>
> +bool
> +is_command_line_args_parsed(void)
> +{
> + return g_command_line_args_parsed;
> +}
> +
> /* Due to various hard-coded priorities need to implement ACLs, the
> * northbound database supports a smaller range of ACL priorities than
> * are available to logical flows. This value is added to an ACL
> @@ -2490,6 +2498,7 @@ parse_options(int argc OVS_UNUSED, char *argv[]
> OVS_UNUSED)
> }
>
> free(short_options);
> + g_command_line_args_parsed = true;
> }
>
> static void
> diff --git a/third-party/function_tracer.c b/third-party/function_tracer.c
> new file mode 100644
> index 0000000..422fccd
> --- /dev/null
> +++ b/third-party/function_tracer.c
> @@ -0,0 +1,126 @@
> +/*
> + * This file implements routines needed to log all function calls'
> + * entry and exit timestamps along with it's hex address. With
> + * python tool generate_ft_report.py, this log can be converted with
> + * symbol names for offline analysis.
> + */
> +
> +#include <stdio.h>
> +#include <sys/types.h>
> +#include <unistd.h>
> +#include <time.h>
> +#include <sys/time.h>
> +#include <string.h>
> +#include "openvswitch/vlog.h"
> +
> +VLOG_DEFINE_THIS_MODULE(trace);
> +
> +#define LOG_FILE_NAME_LEN 256
> +#define LOG_DIR_NAME_LEN 128
> +#define LOG_FILENAME_PREFIX "func_trace"
> +#define CURRENT_LOG_LEVEL this_module.min_level
> +
> +/* File pointer for logging the trace output. */
> +static FILE *log_fp;
> +
> +/* External functions used here */
> +extern bool is_command_line_args_parsed();
> +
> +/* Prototypes for the functions declared/used in this file. */
> +void __attribute__ ((constructor,no_instrument_function)) ft_begin(void);
> +void __attribute__ ((destructor,no_instrument_function)) ft_end(void);
> +void __attribute__ ((no_instrument_function)) ft(const char * direction,
> + void *func, void *
> caller);
> +void __attribute__ ((no_instrument_function)) __cyg_profile_func_enter(
> + void *func, void
> *caller);
> +void __attribute__ ((no_instrument_function)) __cyg_profile_func_exit(
> + void *func, void
> *caller);
> +int __attribute__ ((no_instrument_function)) format_time(struct timeval
> *lt,
> + char *buf,
> + size_t size);
> +
> +void __attribute__ ((constructor,no_instrument_function))
> +ft_begin(void)
> +{
> + /* Nothing at this point, but needed */
> +}
> +
> +void __attribute__ ((no_instrument_function))
> +ft_log_open(void)
> +{
> + char log_name[LOG_FILE_NAME_LEN];
> + char dir_name[LOG_DIR_NAME_LEN];
> +
> + vlog_directory(dir_name, LOG_DIR_NAME_LEN);
> + snprintf(log_name, LOG_FILE_NAME_LEN, "%s/%s_%d.log",
> + dir_name, LOG_FILENAME_PREFIX, getpid());
> + if ((log_fp = fopen(log_name, "w")) == NULL) {
> + fprintf(stderr, "Failed to open output trace file: %s\n",
> log_name);
> + }
> +}
> +
> +
> +void __attribute__ ((destructor,no_instrument_function))
> +ft_end(void)
> +{
> + if (log_fp != NULL) {
> + fclose(log_fp);
> + }
> +}
> +
> +/* Gets the current timestamp into the input buffer in ascii format */
> +int __attribute__ ((no_instrument_function))
> +format_time(struct timeval *lt, char *buf, size_t size)
> +{
> + struct tm gm_time;
> + int bytes_written = -1;
> +
> + gmtime_r(<->tv_sec,&gm_time);
> + bytes_written = strftime(buf, size, "%Y-%m-%dT%H:%M:%S", &gm_time);
> + if ((bytes_written > 0) && ((size_t) bytes_written < size)) {
> + int tmp = snprintf(buf + bytes_written,
> + size - (size_t) bytes_written, ".%06d",
> + (int) lt->tv_usec);
> + bytes_written = (tmp > 0) ? bytes_written + tmp : -1;
> + }
> + return bytes_written;
> +}
> +
> +
> +void __attribute__ ((no_instrument_function))
> +ft(const char *direction, void *func, void *caller)
> +{
> + char timestr[64];
> + struct timeval ltime;
> +
> + if (log_fp == NULL && is_command_line_args_parsed()) {
> + ft_log_open();
> + }
> + if ((!is_command_line_args_parsed()) || (log_fp == NULL)) {
> + return;
> + }
> + if (gettimeofday(<ime, NULL) != 0) {
> + return;
> + }
> + if (format_time(<ime, timestr, sizeof(timestr)) <= 0) {
> + return;
> + }
> + /* Trace only if log level is >= DEBUG */
> + if (CURRENT_LOG_LEVEL >= VLL_DBG) {
> + fprintf(log_fp, "%s>%s>%p>%p\n", timestr,
> + direction, func, caller);
> + }
> + fflush(log_fp);
> +}
> +
> +void __attribute__ ((no_instrument_function))
> +__cyg_profile_func_enter(void *func, void *caller)
> +{
> + ft("entry", func, caller);
> +}
> +
> +void __attribute__ ((no_instrument_function))
> +__cyg_profile_func_exit(void *func, void *caller)
> +{
> + ft("exit", func, caller);
> +}
> diff --git a/third-party/generate_ft_report.py
> b/third-party/generate_ft_report.py
> new file mode 100644
> index 0000000..7e49489
> --- /dev/null
> +++ b/third-party/generate_ft_report.py
> @@ -0,0 +1,80 @@
> +#!/usr/bin/env python
> +# Copyright (c) 2016 Red Hat, Inc.
> +#
> +# Licensed under the Apache License, Version 2.0 (the "License");
> +# you may not use this file except in compliance with the License.
> +# You may obtain a copy of the License at:
> +#
> +# http://www.apache.org/licenses/LICENSE-2.0
> +#
> +# Unless required by applicable law or agreed to in writing, software
> +# distributed under the License is distributed on an "AS IS" BASIS,
> +# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
> +# See the License for the specific language governing permissions and
> +# limitations under the License.
> +import sys
> +import subprocess
> +from datetime import datetime
> +
> +# functions hold the details regarding when it was called, when it was
> complete
> +functions = {}
> +
> +def find_symbol_name(func_addr, exe):
> + """Give the hex address of a method, this returns the symbol name
> + """
> + p = subprocess.Popen("addr2line -e " + exe + ' --functions ' +
> + func_addr, stdout=subprocess.PIPE, shell=True)
> + (out,err) = p.communicate()
> + if not err:
> + tokens = out.split()
> + return tokens[0]
> + return func_addr + "(unknown)"
> +
> +def time_diff(time1, time2):
> + """This method finds the delta between two times passed
> + """
> + date_obj1 = datetime.strptime(time1, '%Y-%m-%dT%H:%M:%S.%f')
> + date_obj2 = datetime.strptime(time2, '%Y-%m-%dT%H:%M:%S.%f')
> + delta = date_obj2 - date_obj1
> + return delta
> +
> +def update_and_print(tstamp, direction, called, caller,
> + serial, exe, verbose=False):
> + """This method updates the exit-point of a function in functions map,
> + finds out the execution time of that function and prints in human-
> + readable format.
> + """
> + func_name = find_symbol_name(called, exe)
> + if direction == "exit":
> + ## Find out corresponding entry point,
> + try:
> + entry = functions[func_name]
> + if verbose:
> + print "ENTRY:%s EXIT %s" %(entry['timestamp'], tstamp)
> + diff = time_diff(entry['timestamp'],tstamp)
> + print "%d %s %s %s" %(entry['serial'], func_name,
> + entry['caller'], diff)
> + except Exception, ex:
> + print "Exception %s" %ex
> + else:
> + functions[func_name] = {'timestamp':tstamp, 'caller':caller,
> + 'serial':serial}
> +
> +
> +def main():
> + if len(sys.argv) != 3:
> + print "Usage: %s <exe-file> <log-file>" %sys.argv[0]
> + return
> + exe = sys.argv[1]
> + filename = sys.argv[2]
> + serial = 0
> + with open(filename) as f:
> + for line in f:
> + serial += 1
> + tokens = line.strip().split('>')
> + #arguments (timestamp, dirn, called, caller,serial,exe)
> + update_and_print(tokens[0], tokens[1], tokens[2],
> + tokens[3], serial, exe)
> +
> +if __name__ == "__main__":
> + main()
> diff --git a/utilities/automake.mk b/utilities/automake.mk
> index 1cc66b6..747cb36 100644
> --- a/utilities/automake.mk
> +++ b/utilities/automake.mk
> @@ -57,6 +57,7 @@ EXTRA_DIST += \
> utilities/ovs-vlan-test.in \
> utilities/ovs-vsctl-bashcomp.bash \
> utilities/qemu-wrap.py \
> + third-party/generate_ft_report.py \
> utilities/checkpatch.py
> MAN_ROOTS += \
> utilities/ovs-appctl.8.in \
> diff --git a/vswitchd/automake.mk b/vswitchd/automake.mk
> index 8d7f3ea..bc4cd54 100644
> --- a/vswitchd/automake.mk
> +++ b/vswitchd/automake.mk
> @@ -1,3 +1,8 @@
> +if ENABLE_FT
> +CFLAGS += -g -finstrument-functions \
> + `pkg-config --cflags glib-2.0` \
> + `pkg-config --libs glib-2.0` -ldl -export-dynamic -lrt
> +endif
> sbin_PROGRAMS += vswitchd/ovs-vswitchd
> man_MANS += vswitchd/ovs-vswitchd.8
> DISTCLEANFILES += \
> @@ -11,6 +16,9 @@ vswitchd_ovs_vswitchd_SOURCES = \
> vswitchd/system-stats.h \
> vswitchd/xenserver.c \
> vswitchd/xenserver.h
> +if ENABLE_FT
> +vswitchd_ovs_vswitchd_SOURCES += third-party/function_tracer.c
> +endif
> vswitchd_ovs_vswitchd_LDADD = \
> ofproto/libofproto.la \
> lib/libsflow.la \
> diff --git a/vswitchd/ovs-vswitchd.c b/vswitchd/ovs-vswitchd.c
> index 72448bb..ba985fd 100644
> --- a/vswitchd/ovs-vswitchd.c
> +++ b/vswitchd/ovs-vswitchd.c
> @@ -51,6 +51,7 @@
>
> VLOG_DEFINE_THIS_MODULE(vswitchd);
>
> +static bool g_command_line_args_parsed = false;
> /* --mlockall: If set, locks all process memory into physical RAM,
> preventing
> * the kernel from paging any of its memory to disk. */
> static bool want_mlockall;
> @@ -60,6 +61,12 @@ static unixctl_cb_func ovs_vswitchd_exit;
> static char *parse_options(int argc, char *argv[], char **unixctl_path);
> OVS_NO_RETURN static void usage(void);
>
> +bool
> +is_command_line_args_parsed(void)
> +{
> + return g_command_line_args_parsed;
> +}
> +
> int
> main(int argc, char *argv[])
> {
> @@ -240,6 +247,7 @@ parse_options(int argc, char *argv[], char
> **unixctl_pathp)
> VLOG_FATAL("at most one non-option argument accepted; "
> "use --help for usage");
> }
> + g_command_line_args_parsed = true;
> }
>
> static void
> --
> 1.9.1
>
> _______________________________________________
> dev mailing list
> dev at openvswitch.org
> http://openvswitch.org/mailman/listinfo/dev
>
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