MAP_POPULATE performance with ext3

Performance of mmap_read without MAP_POPULATE, around 90 MB/sec

XXX_01:~ # ~/a.out -i /tmp/test/testfile
Time taken : 22 sec
Data Read : 2097152000 bytes
Speed is : 90.909091 MB/sec
XXX_01:~ #
XXX_01:~ # umount /tmp/test; mount  /dev/vx/dsk/vxvmdg/fs_iscsi_ext3 /tmp/test
XXX_01:~ # ~/a.out -i /tmp/test/testfile
Time taken : 22 sec
Data Read : 2097152000 bytes
Speed is : 90.909091 MB/sec
XXX_01:~ #

Performance wih MAP_POPULATE, around 86 MB/sec

XXX_01:~ # ~/a.out -i /tmp/test/testfile
Time taken : 23 sec
Data Read : 2097152000 bytes
Speed is : 86.956522 MB/sec
XXX_01:~ #
XXX_01:~ # umount /tmp/test; mount  /dev/vx/dsk/vxvmdg/fs_iscsi_ext3 /tmp/test
XXX_01:~ # ~/a.out -i /tmp/test/testfile
Time taken : 23 sec
Data Read : 2097152000 bytes
Speed is : 86.956522 MB/sec
XXX_01:~ #

Looks like the built-in read-head of ext3 or linux is good enough without the need for MAP_POPULATE when used with mmap