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trace: Support disabled events in trace-events

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Sometimes it is useful to disable a trace event.  Removing the event
from trace-events is not enough since source code will call the
trace_*() function for the event.

This patch makes it easy to build without specific trace events by
marking them disabled in trace-events:

disable multiwrite_cb(void *mcb, int ret) "mcb %p ret %d"

This builds without the multiwrite_cb trace event.

Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>

trace: Allow bulk enabling/disabling of trace events at compile time

For 'simple' trace backend, allow bulk enabling/disabling of trace
events at compile time.  Trace events that are preceded by 'disable'
keyword are compiled in, but turned off by default. These can
individually be turned on using the monitor.  All other trace events are
enabled by default.

TODO :
This could be enhanced when the trace-event namespace is partitioned into a
group and an ID within that group. In such a case, marking a group as enabled
would automatically enable all trace-events listed under it.

Signed-off-by: Prerna Saxena <prerna@linux.vnet.ibm.com>
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
This commit is contained in:
Stefan Hajnoczi 2010-05-24 11:32:09 +01:00 committed by Anthony Liguori
parent 22890ab5e8
commit 1e2cf2bc45
2 changed files with 45 additions and 6 deletions
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7
trace-events
View File

@ -12,10 +12,15 @@
#
# Format of a trace event:
#
# <name>(<type1> <arg1>[, <type2> <arg2>] ...) "<format-string>"
# [disable] <name>(<type1> <arg1>[, <type2> <arg2>] ...) "<format-string>"
#
# Example: qemu_malloc(size_t size) "size %zu"
#
# The "disable" keyword will build without the trace event.
# In case of 'simple' trace backend, it will allow the trace event to be
# compiled, but this would be turned off by default. It can be toggled on via
# the monitor.
#
# The <name> must be a valid as a C function name.
#
# Types should be standard C types. Use void * for pointers because the trace

44
tracetool
View File

@ -87,6 +87,20 @@ get_fmt()
echo "$fmt"
}
# Get the state of a trace event
get_state()
{
local str disable state
str=$(get_name "$1")
disable=${str##disable }
if [ "$disable" = "$str" ] ; then
state=1
else
state=0
fi
echo "$state"
}
linetoh_begin_nop()
{
return
@ -146,10 +160,14 @@ cast_args_to_uint64_t()
linetoh_simple()
{
local name args argc trace_args
local name args argc trace_args state
name=$(get_name "$1")
args=$(get_args "$1")
argc=$(get_argc "$1")
state=$(get_state "$1")
if [ "$state" = "0" ]; then
name=${name##disable }
fi
trace_args="$simple_event_num"
if [ "$argc" -gt 0 ]
@ -188,10 +206,14 @@ EOF
linetoc_simple()
{
local name
local name state
name=$(get_name "$1")
state=$(get_state "$1")
if [ "$state" = "0" ] ; then
name=${name##disable }
fi
cat <<EOF
{.tp_name = "$name", .state=0},
{.tp_name = "$name", .state=$state},
EOF
simple_event_num=$((simple_event_num + 1))
}
@ -206,7 +228,7 @@ EOF
# Process stdin by calling begin, line, and end functions for the backend
convert()
{
local begin process_line end
local begin process_line end str disable
begin="lineto$1_begin_$backend"
process_line="lineto$1_$backend"
end="lineto$1_end_$backend"
@ -218,8 +240,20 @@ convert()
str=${str%%#*}
test -z "$str" && continue
# Process the line. The nop backend handles disabled lines.
disable=${str%%disable *}
echo
"$process_line" "$str"
if test -z "$disable"; then
# Pass the disabled state as an arg to lineto$1_simple().
# For all other cases, call lineto$1_nop()
if [ $backend = "simple" ]; then
"$process_line" "$str"
else
"lineto$1_nop" "${str##disable }"
fi
else
"$process_line" "$str"
fi
done
echo