Measuring peak disk use of a process

I am trying to benchmark a tool I'm developing in terms of time, memory, and disk use. I know /usr/bin/time gives me basically what I want for the first two, but for disk use I came to the conclusion I would have to roll my own bash script that periodically extracts the 'bytes written' contents from /proc/<my_pid>/io. Based on this script, here's what I came up with:

"$@" &
pid=$!
status=$(ps -o rss -o vsz -o pid | grep $pid)
maxdisk=0
while [ "${#status}" -gt "0" ];
do
    sleep 0.05
    delta=false
    disk=$(cat /proc/$pid/io | grep -P '^write_bytes:' | awk '{print $2}')
    disk=$(disk/1024)
    if [ "0$disk" -gt "0$maxdisk" ] 2>/dev/null; then
        maxdisk=$disk
        delta=true
    fi
    if $delta; then
        echo disk: $disk
    fi
    status=$(ps -o rss -o vsz -o pid | grep $pid)
done
wait $pid
ret=$?
echo "maximal disk used: $maxdisk KB"

Unfortunately, I am running into two problems:

• The first is that I am piping the output of this script along with that of the tool I would like to benchmark to a file, and it seems occasionally these streams interfere, leading me to see 0 or too low disk use reported at the bottom of this file.
• The second problem is that I don't know what to do about processes that delete temporary files as part of their process. In this case I think the fair benchmark would be to record the maximum net disk use (i.e., the peak in bytes written - bytes erased), but I don't know where the second part of this difference can be found.

How can I resolve these problems?

You may like to have a look at filetop from BCC - Tools for BPF-based Linux IO analysis, networking, monitoring, and more:

tools/filetop: File reads and writes by filename and process. Top for files.

This script works by tracing the vfs_read() and vfs_write() functions using kernel dynamic tracing, which instruments explicit read and write calls. If files are read or written using another means (eg, via mmap()), then they will not be visible using this tool.

Brendan Gregg gives good talks and demos about Linux Performance Tools, they are quite instructive.