Re: [Qemu-devel] [PATCH 1/2] Add a DTrace tracing backend targetted for SystemTAP compatability

[Anthony Liguori <anthony@codemonkey.ws>]

On 11/08/2010 01:33 PM, Daniel P. Berrange wrote:
> This introduces a new tracing backend that targets the SystemTAP
> implementation of DTrace userspace tracing. The core functionality
> should be applicable and standard across any DTrace implementation
> on Solaris, OS-X, *BSD, but the Makefile rules will likely need
> some small additional changes to cope with OS specific build
> requirements.
>
> This backend builds a little differently from the other tracing
> backends. Specifically there is no 'trace.c' file, because the
> 'dtrace' command line tool generates a '.o' file directly from
> the dtrace probe definition file. The probe definition is usually
> named with a '.d' extension but QEMU uses '.d' files for its
> external makefile dependancy tracking, so this uses '.dtrace' as
> the extension for the probe definition file.
>
> The 'tracetool' program gains the ability to generate a trace.h
> file for DTrace, and also to generate the trace.d file containing
> the dtrace probe definition.
>
> Example usage of a dtrace probe in systemtap looks like:
>
>    probe process("qemu").mark("qemu_malloc") {
>      printf("Malloc %d %p\n", $arg1, $arg2);
>    }
>
> * .gitignore: Ignore trace-dtrace.*
> * Makefile: Extra rules for generating DTrace files
> * Makefile.obj: Don't build trace.o for DTrace, use
>    trace-dtrace.o generated by 'dtrace' instead
> * tracetool: Support for generating DTrace data files
>
> Signed-off-by: Daniel P. Berrange<berrange@redhat.com>
>    

Applied both.  Thanks.

Regards,

Anthony Liguori

> ---
>   .gitignore    |    2 +
>   Makefile      |   23 +++++++++++
>   Makefile.objs |    4 ++
>   configure     |   14 ++++++-
>   tracetool     |  116 ++++++++++++++++++++++++++++++++++++++++++++++++++++-----
>   5 files changed, 148 insertions(+), 11 deletions(-)
>
> diff --git a/.gitignore b/.gitignore
> index a43e4d1..3efb4ec 100644
> --- a/.gitignore
> +++ b/.gitignore
> @@ -4,6 +4,8 @@ config-host.*
>   config-target.*
>   trace.h
>   trace.c
> +trace-dtrace.h
> +trace-dtrace.dtrace
>   *-timestamp
>   *-softmmu
>   *-darwin-user
> diff --git a/Makefile b/Makefile
> index 02698e9..554ad97 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -1,6 +1,9 @@
>   # Makefile for QEMU.
>
>   GENERATED_HEADERS = config-host.h trace.h qemu-options.def
> +ifeq ($(TRACE_BACKEND),dtrace)
> +GENERATED_HEADERS += trace-dtrace.h
> +endif
>
>   ifneq ($(wildcard config-host.mak),)
>   # Put the all: rule here so that config-host.mak can contain dependencies.
> @@ -108,7 +111,11 @@ ui/vnc.o: QEMU_CFLAGS += $(VNC_TLS_CFLAGS)
>
>   bt-host.o: QEMU_CFLAGS += $(BLUEZ_CFLAGS)
>
> +ifeq ($(TRACE_BACKEND),dtrace)
> +trace.h: trace.h-timestamp trace-dtrace.h
> +else
>   trace.h: trace.h-timestamp
> +endif
>   trace.h-timestamp: $(SRC_PATH)/trace-events config-host.mak
>   	$(call quiet-command,sh $(SRC_PATH)/tracetool --$(TRACE_BACKEND) -h<  $<  >  $@,"  GEN   trace.h")
>   	@cmp -s $@ trace.h || cp $@ trace.h
> @@ -120,6 +127,20 @@ trace.c-timestamp: $(SRC_PATH)/trace-events config-host.mak
>
>   trace.o: trace.c $(GENERATED_HEADERS)
>
> +trace-dtrace.h: trace-dtrace.dtrace
> +	$(call quiet-command,dtrace -o $@ -h -s $<, "  GEN   trace-dtrace.h")
> +
> +# Normal practice is to name DTrace probe file with a '.d' extension
> +# but that gets picked up by QEMU's Makefile as an external dependancy
> +# rule file. So we use '.dtrace' instead
> +trace-dtrace.dtrace: trace-dtrace.dtrace-timestamp
> +trace-dtrace.dtrace-timestamp: $(SRC_PATH)/trace-events config-host.mak
> +	$(call quiet-command,sh $(SRC_PATH)/tracetool --$(TRACE_BACKEND) -d<  $<  >  $@,"  GEN   trace-dtrace.dtrace")
> +	@cmp -s $@ trace-dtrace.dtrace || cp $@ trace-dtrace.dtrace
> +
> +trace-dtrace.o: trace-dtrace.dtrace $(GENERATED_HEADERS)
> +	$(call quiet-command,dtrace -o $@ -G -s $<, "  GEN trace-dtrace.o")
> +
>   simpletrace.o: simpletrace.c $(GENERATED_HEADERS)
>
>   version.o: $(SRC_PATH)/version.rc config-host.mak
> @@ -157,6 +178,8 @@ clean:
>   	rm -f slirp/*.o slirp/*.d audio/*.o audio/*.d block/*.o block/*.d net/*.o net/*.d fsdev/*.o fsdev/*.d ui/*.o ui/*.d
>   	rm -f qemu-img-cmds.h
>   	rm -f trace.c trace.h trace.c-timestamp trace.h-timestamp
> +	rm -f trace-dtrace.dtrace trace-dtrace.dtrace-timestamp
> +	rm -f trace-dtrace.h trace-dtrace.h-timestamp
>   	$(MAKE) -C tests clean
>   	for d in $(ALL_SUBDIRS) libhw32 libhw64 libuser libdis libdis-user; do \
>   	if test -d $$d; then $(MAKE) -C $$d $@ || exit 1; fi; \
> diff --git a/Makefile.objs b/Makefile.objs
> index faf485e..84fc80e 100644
> --- a/Makefile.objs
> +++ b/Makefile.objs
> @@ -285,11 +285,15 @@ libdis-$(CONFIG_SPARC_DIS) += sparc-dis.o
>   ######################################################################
>   # trace
>
> +ifeq ($(TRACE_BACKEND),dtrace)
> +trace-obj-y = trace-dtrace.o
> +else
>   trace-obj-y = trace.o
>   ifeq ($(TRACE_BACKEND),simple)
>   trace-obj-y += simpletrace.o
>   user-obj-y += qemu-timer-common.o
>   endif
> +endif
>
>   vl.o: QEMU_CFLAGS+=$(GPROF_CFLAGS)
>
> diff --git a/configure b/configure
> index 7025d2b..f8dad3e 100755
> --- a/configure
> +++ b/configure
> @@ -929,7 +929,7 @@ echo "  --enable-docs            enable documentation build"
>   echo "  --disable-docs           disable documentation build"
>   echo "  --disable-vhost-net      disable vhost-net acceleration support"
>   echo "  --enable-vhost-net       enable vhost-net acceleration support"
> -echo "  --trace-backend=B        Trace backend nop simple ust"
> +echo "  --trace-backend=B        Trace backend nop simple ust dtrace"
>   echo "  --trace-file=NAME        Full PATH,NAME of file to store traces"
>   echo "                           Default:trace-<pid>"
>   echo "  --disable-spice          disable spice"
> @@ -2193,6 +2193,18 @@ EOF
>       exit 1
>     fi
>   fi
> +
> +##########################################
> +# For 'dtrace' backend, test if 'dtrace' command is present
> +if test "$trace_backend" = "dtrace"; then
> +  if ! has 'dtrace' ; then
> +    echo
> +    echo "Error: dtrace command is not found in PATH $PATH"
> +    echo
> +    exit 1
> +  fi
> +fi
> +
>   ##########################################
>   # End of CC checks
>   # After here, no more $cc or $ld runs
> diff --git a/tracetool b/tracetool
> index 7010858..5b6636a 100755
> --- a/tracetool
> +++ b/tracetool
> @@ -20,10 +20,12 @@ Backends:
>     --nop     Tracing disabled
>     --simple  Simple built-in backend
>     --ust     LTTng User Space Tracing backend
> +  --dtrace  DTrace/SystemTAP backend
>
>   Output formats:
>     -h    Generate .h file
>     -c    Generate .c file
> +  -d    Generate .d file (DTrace only)
>   EOF
>       exit 1
>   }
> @@ -46,8 +48,9 @@ get_args()
>   # Get the argument name list of a trace event
>   get_argnames()
>   {
> -    local nfields field name
> +    local nfields field name sep
>       nfields=0
> +    sep="$2"
>       for field in $(get_args "$1"); do
>           nfields=$((nfields + 1))
>
> @@ -58,7 +61,7 @@ get_argnames()
>           name=${field%,}
>           test "$field" = "$name"&&  continue
>
> -        printf "%s" "$name, "
> +        printf "%s%s " $name $sep
>       done
>
>       # Last argument name
> @@ -73,7 +76,7 @@ get_argc()
>   {
>       local name argc
>       argc=0
> -    for name in $(get_argnames "$1"); do
> +    for name in $(get_argnames "$1", ","); do
>           argc=$((argc + 1))
>       done
>       echo $argc
> @@ -154,7 +157,7 @@ EOF
>   cast_args_to_uint64_t()
>   {
>       local arg
> -    for arg in $(get_argnames "$1"); do
> +    for arg in $(get_argnames "$1", ","); do
>           printf "%s" "(uint64_t)(uintptr_t)$arg"
>       done
>   }
> @@ -247,7 +250,7 @@ linetoh_ust()
>       local name args argnames
>       name=$(get_name "$1")
>       args=$(get_args "$1")
> -    argnames=$(get_argnames "$1")
> +    argnames=$(get_argnames "$1", ",")
>
>       cat<<EOF
>   DECLARE_TRACE(ust_$name, TP_PROTO($args), TP_ARGS($argnames));
> @@ -274,7 +277,7 @@ linetoc_ust()
>       local name args argnames fmt
>       name=$(get_name "$1")
>       args=$(get_args "$1")
> -    argnames=$(get_argnames "$1")
> +    argnames=$(get_argnames "$1", ",")
>       fmt=$(get_fmt "$1")
>
>       cat<<EOF
> @@ -306,6 +309,87 @@ EOF
>       echo "}"
>   }
>
> +linetoh_begin_dtrace()
> +{
> +    cat<<EOF
> +#include "trace-dtrace.h"
> +EOF
> +}
> +
> +linetoh_dtrace()
> +{
> +    local name args argnames state nameupper
> +    name=$(get_name "$1")
> +    args=$(get_args "$1")
> +    argnames=$(get_argnames "$1", ",")
> +    state=$(get_state "$1")
> +    if [ "$state" = "0" ] ; then
> +        name=${name##disable }
> +    fi
> +
> +    nameupper=`echo $name | tr '[:lower:]' '[:upper:]'`
> +
> +    # Define an empty function for the trace event
> +    cat<<EOF
> +static inline void trace_$name($args) {
> +    if (QEMU_${nameupper}_ENABLED()) {
> +        QEMU_${nameupper}($argnames);
> +    }
> +}
> +EOF
> +}
> +
> +linetoh_end_dtrace()
> +{
> +    return
> +}
> +
> +linetoc_begin_dtrace()
> +{
> +    return
> +}
> +
> +linetoc_dtrace()
> +{
> +    # No need for function definitions in dtrace backend
> +    return
> +}
> +
> +linetoc_end_dtrace()
> +{
> +    return
> +}
> +
> +linetod_begin_dtrace()
> +{
> +    cat<<EOF
> +provider qemu {
> +EOF
> +}
> +
> +linetod_dtrace()
> +{
> +    local name args state
> +    name=$(get_name "$1")
> +    args=$(get_args "$1")
> +    state=$(get_state "$1")
> +    if [ "$state" = "0" ] ; then
> +        name=${name##disable }
> +    fi
> +
> +    # Define prototype for probe arguments
> +    cat<<EOF
> +        probe $name($args);
> +EOF
> +}
> +
> +linetod_end_dtrace()
> +{
> +    cat<<EOF
> +};
> +EOF
> +}
> +
>   # Process stdin by calling begin, line, and end functions for the backend
>   convert()
>   {
> @@ -324,9 +408,10 @@ convert()
>           disable=${str%%disable *}
>           echo
>           if test -z "$disable"; then
> -            # Pass the disabled state as an arg to lineto$1_simple().
> -            # For all other cases, call lineto$1_nop()
> -            if [ $backend = "simple" ]; then
> +            # Pass the disabled state as an arg for the simple
> +            # or DTrace backends which handle it dynamically.
> +            # For all other backends, call lineto$1_nop()
> +            if [ $backend = "simple" -o "$backend" = "dtrace" ]; then
>                   "$process_line" "$str"
>               else
>                   "lineto$1_nop" "${str##disable }"
> @@ -360,9 +445,19 @@ tracetoc()
>       convert c
>   }
>
> +tracetod()
> +{
> +    if [ $backend != "dtrace" ]; then
> +       echo "DTrace probe generator not applicable to $backend backend"
> +       exit 1
> +    fi
> +    echo "/* This file is autogenerated by tracetool, do not edit. */"
> +    convert d
> +}
> +
>   # Choose backend
>   case "$1" in
> -"--nop" | "--simple" | "--ust") backend="${1#--}" ;;
> +"--nop" | "--simple" | "--ust" | "--dtrace") backend="${1#--}" ;;
>   *) usage ;;
>   esac
>   shift
> @@ -370,6 +465,7 @@ shift
>   case "$1" in
>   "-h") tracetoh ;;
>   "-c") tracetoc ;;
> +"-d") tracetod ;;
>   "--check-backend") exit 0 ;; # used by ./configure to test for backend
>   *) usage ;;
>   esac
>