btrfstest.sh

#!/bin/bash

mode=$1
if [ -z "$mode" ]; then
    echo "Usage $0 <incremental|random|fixed>"
    exit -1
fi
mode=$1

src=`pwd`/test/src
dst=`pwd`/test/dst
srcfile=$src/test.tar
dstfile=$dst/test.tar

mkdir -p $src
mkdir -p $dst

filesize=100MB

#build a 10GB file from a smaller download. You can tweak filesize and the loop below for lower bandwidth
if [ ! -f $srcfile ]; then
    cd $src
    if [ ! -f $srcfile.dl ]; then
        wget http://download.thinkbroadband.com/${filesize}.zip --output-document=$srcfile.dl
    fi
    rm -rf tarbase
    mkdir tarbase
    for  i in {1..100}; do
        cp --reflink=always $srcfile.dl tarbase/$i.dl
    done
    tar -cvf $srcfile tarbase
    rm -rf tarbase
fi

cat <<END > $src/FileTest.java
import java.io.IOException;
import java.io.RandomAccessFile;
public class FileTest {
    public static final int BLOCK_SIZE = 50000;
    public static final int MAX_ITERATIONS = 40000;
    public static void main(String args[]) throws IOException {
        String mode = args[0];
        RandomAccessFile f = new RandomAccessFile(args[1], "rw");
        //int offset = 0;
        int i;
        int offset = new java.util.Random().nextInt(BLOCK_SIZE); // initializer ONLY for incremental mode
        for (i=0; i < MAX_ITERATIONS; i++) {
            try {
                int writeOffset;
                if (mode.equals("incremental")) {
                    writeOffset = new java.util.Random().nextInt(offset + i * BLOCK_SIZE);
                }  else if (mode.equals("fixed")) {
                    writeOffset = i * BLOCK_SIZE;
                    offset = writeOffset; // for reporting it at the end
                } else { // mode.equals random
                    writeOffset = new java.util.Random().nextInt(((int)f.length() - 100));
                    offset = writeOffset; // for reporting it at the end
                }
        if (writeOffset > (f.length() - 100)) {
            break;
        }
                f.seek(writeOffset);
                f.writeBytes("DEADBEEF");
            } catch (java.io.IOException e) {
                System.out.println("EOF");
                break;
            }
        }
        //System.out.print("Last offset=" + offset);
        //System.out.println(". Made " + i + " random writes.");
        f.close();
    }
}
END

cd $src
javac FileTest.java


/usr/bin/time --format 'rm: %E' rm -rf $dst/*
cp --reflink=always $srcfile $dst/1.tst
popd

pushd $dst
for i in {1..20}; do
    echo -n "$i."
    i_plus=`expr $i + 1`
    write[$i]=`/usr/bin/time --format '%e' java -cp $src FileTest $mode $i.tst 2>&1`
    cp[$i]=`/usr/bin/time --format '%e' cp --reflink=always $i.tst $i_plus.tst 2>&1`
    rm[$i]=`/usr/bin/time --format '%e' rm $i.tst 2>&1`
    sync[$i]=`/usr/bin/time --format '%e' sync 2>&1`
    sleep 1
done
echo "write cp  rm  sync" > ${mode}.csv
popd

for i in {1..20}; do
    echo "${write[$i]}  ${cp[$i]}   ${rm[$i]}   ${sync[$i]}" >> ${mode}.csv
done
echo -n