Current File : //lib/dracut/modules.d/99base/memtrace-ko.sh
#!/bin/sh
# Try to find out kernel modules with large total memory allocation during loading.
# For large slab allocation, it will fall into buddy, also not trace "mm_page_free"
# considering large free is quite rare for module_init, thus saving tons of events
# to avoid trace data overwritten.
#
# Therefore, tracing "mm_page_alloc"alone should be enough for the purpose.
# "sys/kernel/tracing" has the priority if exists.
get_trace_base() {
# trace access through debugfs would be obsolete if "/sys/kernel/tracing" is available.
if [ -d "/sys/kernel/tracing" ]; then
echo "/sys/kernel"
else
echo "/sys/kernel/debug"
fi
}
# We want to enable these trace events.
get_want_events() {
echo "module:module_put module:module_load kmem:mm_page_alloc"
}
get_event_filter() {
echo "comm == systemd-udevd || comm == modprobe || comm == insmod"
}
is_trace_ready() {
local trace_base want_events current_events
trace_base=$(get_trace_base)
! [ -f "$trace_base/tracing/trace" ] && return 1
[ "$(cat $trace_base/tracing/tracing_on)" -eq 0 ] && return 1
# Also check if trace events were properly setup.
want_events=$(get_want_events)
current_events=$(echo $(cat $trace_base/tracing/set_event))
[ "$current_events" != "$want_events" ] && return 1
return 0
}
prepare_trace() {
local trace_base
trace_base=$(get_trace_base)
# old debugfs interface case.
if ! [ -d "$trace_base/tracing" ]; then
mount none -t debugfs $trace_base
# new tracefs interface case.
elif ! [ -f "$trace_base/tracing/trace" ]; then
mount none -t tracefs "$trace_base/tracing"
fi
if ! [ -f "$trace_base/tracing/trace" ]; then
echo "WARN: Mount trace failed for kernel module memory analyzing."
return 1
fi
# Active all the wanted trace events.
echo "$(get_want_events)" > $trace_base/tracing/set_event
# There are three kinds of known applications for module loading:
# "systemd-udevd", "modprobe" and "insmod".
# Set them as the global events filter.
# NOTE: Some kernel may not support this format of filter, anyway
# the operation will fail and it doesn't matter.
echo "$(get_event_filter)" > $trace_base/tracing/events/kmem/filter 2>&1
echo "$(get_event_filter)" > $trace_base/tracing/events/module/filter 2>&1
# Set the number of comm-pid if supported.
if [ -f "$trace_base/tracing/saved_cmdlines_size" ]; then
# Thanks to filters, 4096 is big enough(also well supported).
echo 4096 > $trace_base/tracing/saved_cmdlines_size
fi
# Enable and clear trace data for the first time.
echo 1 > $trace_base/tracing/tracing_on
echo > $trace_base/tracing/trace
echo "Prepare trace success."
return 0
}
order_to_pages()
{
local pages=1
local order=$1
while [ "$order" != 0 ]; do
order=$((order-1))
pages=$(($pages*2))
done
echo $pages
}
parse_trace_data() {
local module_name tmp_eval pages
cat "$(get_trace_base)/tracing/trace" | while read pid cpu flags ts function args
do
# Skip comment lines
if [ "$pid" = "#" ]; then
continue
fi
pid=${pid##*-}
function=${function%:}
if [ "$function" = "module_load" ]; then
# One module is being loaded, save the task pid for tracking.
# Remove the trailing after whitespace, there may be the module flags.
module_name=${args%% *}
# Mark current_module to track the task.
eval current_module_$pid="$module_name"
tmp_eval=$(eval echo '${module_loaded_'${module_name}'}')
if [ -n "$tmp_eval" ]; then
echo "WARN: \"$module_name\" was loaded multiple times!"
fi
eval unset module_loaded_$module_name
eval nr_alloc_pages_$module_name=0
continue
fi
module_name=$(eval echo '${current_module_'${pid}'}')
if [ -z "$module_name" ]; then
continue
fi
# Once we get here, the task is being tracked(is loading a module).
if [ "$function" = "module_put" ]; then
# Mark the module as loaded when the first module_put event happens after module_load.
tmp_eval=$(eval echo '${nr_alloc_pages_'${module_name}'}')
echo "$tmp_eval pages consumed by \"$module_name\""
eval module_loaded_$module_name=1
# Module loading finished, so untrack the task.
eval unset current_module_$pid
eval unset nr_alloc_pages_$module_name
continue
fi
if [ "$function" = "mm_page_alloc" ]; then
# Get order first, then convert to actual pages.
pages=$(echo $args | sed -e 's/.*order=\([0-9]*\) .*/\1/')
pages=$(order_to_pages "$pages")
tmp_eval=$(eval echo '${nr_alloc_pages_'${module_name}'}')
eval nr_alloc_pages_$module_name="$(($tmp_eval+$pages))"
fi
done
}
cleanup_trace() {
local trace_base
if is_trace_ready; then
trace_base=$(get_trace_base)
echo 0 > $trace_base/tracing/tracing_on
echo > $trace_base/tracing/trace
echo > $trace_base/tracing/set_event
echo 0 > $trace_base/tracing/events/kmem/filter
echo 0 > $trace_base/tracing/events/module/filter
fi
}
show_usage() {
echo "Find out kernel modules with large memory consumption during loading based on trace."
echo "Usage:"
echo "1) run it first to setup trace."
echo "2) run again to parse the trace data if any."
echo "3) run with \"--cleanup\" option to cleanup trace after use."
}
if [ "$1" = "--help" ]; then
show_usage
exit 0
fi
if [ "$1" = "--cleanup" ]; then
cleanup_trace
exit 0
fi
if is_trace_ready ; then
echo "tracekomem - Rough memory consumption by loading kernel modules (larger value with better accuracy)"
parse_trace_data
else
prepare_trace
fi
exit $?
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