ref:http://amay077.github.io/blog/2013/08/29/performance-of-sdcard-io/

SDCardStressTest.java

import java.io.BufferedWriter;
import java.io.File;
import java.io.FileOutputStream;
import java.io.OutputStream;
import java.io.OutputStreamWriter;

import android.content.Context;
import android.os.Environment;
import android.test.InstrumentationTestCase;
import android.util.Log;

public class SDCardStressTest extends InstrumentationTestCase {
    private static final String TAG = "SDCardStressTest";

    public void testStress00100() throws Exception {
        stressN(100);
    }
    
    public void testStress00500() throws Exception {
        stressN(500);
    }
    
    public void testStress01000() throws Exception {
        stressN(1000);
    }
    
    public void testStress05000() throws Exception {
        stressN(5000);
    }

    public void testStress10000() throws Exception {
        stressN(10000);
    }

    private void stressN(int count) throws Exception {
        File dir = Environment.getExternalStorageDirectory();
        File appDataDir = new File(dir.getAbsoluteFile() + "/" + getApplicationContext().getPackageName());
        
        if (appDataDir.exists()) {
            appDataDir.delete();
        }
        appDataDir.mkdirs();

        long[] sums = new long[5];
        for (int i = 0; i < sums.length; i++) { sums[i] = 0; }
        final int times = 5;
        for (int i = 0; i < times; i++) {
            Long[] elapsesA = createRenameDelete(appDataDir, count);
            Long[] elapsesB = createFolderDelete(appDataDir, count);
            
            sums[0] = sums[0] + elapsesA[0];
            sums[1] = sums[1] + elapsesA[1];
            sums[2] = sums[2] + elapsesA[2];
            sums[3] = sums[3] + elapsesA[3];
            sums[4] = sums[4] + elapsesB[0];
        }

        Log.d(TAG, "Count:" + count + 
                  ",Create:" + sums[0]/times + "ms" +
                  ",List:"   + sums[1]/times + "ms" +
                  ",Rename:" + sums[2]/times + "ms" +
                  ",Delete:" + sums[3]/times + "ms" +
                  ",DelDir:" + sums[4]/times + "ms");
    }

    private Long[] createRenameDelete(File appDataDir, int count) throws Exception {
        Long[] elapses = new Long[4];
        File[] files = new File[count];
        File[] renames = new File[count];
        for (int i = 0; i < files.length; i++) {
            files[i] = new File(appDataDir.getAbsolutePath() + "/" + i + ".dat");
            renames[i] = new File(appDataDir.getAbsolutePath() + "/" + i + ".ren");
        }
        
        // Create
        long start = System.currentTimeMillis();
        for (int i = 0; i < files.length; i++) {
            createFile(files[i]);
        }
        elapses[0] = System.currentTimeMillis() - start;
        
        // List
        start = System.currentTimeMillis();
        File[] enums = appDataDir.listFiles();
        for (File file : enums) {
        }
        elapses[1] = System.currentTimeMillis() - start;
        
        // Rename
        start = System.currentTimeMillis();
        for (int i = 0; i < files.length; i++) {
            files[i].renameTo(renames[i]);
        }
        elapses[2] = System.currentTimeMillis() - start;

        // Delete
        start = System.currentTimeMillis();
        for (int i = 0; i < files.length; i++) {
            files[i].delete();
        }
        elapses[3] = System.currentTimeMillis() - start;

        return elapses;
    }

    private Long[] createFolderDelete(File appDataDir, int count) throws Exception {
        Long[] elapses = new Long[1];
        File[] files = new File[count];
        File[] renames = new File[count];
        for (int i = 0; i < files.length; i++) {
            files[i] = new File(appDataDir.getAbsolutePath() + "/" + i + ".dat");
            renames[i] = new File(appDataDir.getAbsolutePath() + "/" + i + ".ren");
        }
        
        for (int i = 0; i < files.length; i++) {
            createFile(files[i]);
        }
        
        // Delete Directory
        long start = System.currentTimeMillis();
        appDataDir.delete();
        elapses[0] = System.currentTimeMillis() - start;
        
        return elapses;
    }

    private void createFile(File file) throws Exception {
        OutputStream fos = new FileOutputStream(file, true);
        OutputStreamWriter osw = new OutputStreamWriter(fos, "UTF-8");
        BufferedWriter bw = new BufferedWriter(osw);
        bw.write("hoge");
        bw.flush();
        bw.close();
    }

    /** ApplicationContext を取得します */
    public Context getApplicationContext() {
        return this.getInstrumentation().getTargetContext().getApplicationContext();
    }
}