• Frank Mayhar's avatar
    ext4: Allow ext4 to run without a journal · 0390131b
    Frank Mayhar authored
    A few weeks ago I posted a patch for discussion that allowed ext4 to run
    without a journal.  Since that time I've integrated the excellent
    comments from Andreas and fixed several serious bugs.  We're currently
    running with this patch and generating some performance numbers against
    both ext2 (with backported reservations code) and ext4 with and without
    a journal.  It just so happens that running without a journal is
    slightly faster for most everything.
    
    We did
    	iozone -T -t 4 s 2g -r 256k -T -I -i0 -i1 -i2
    
    which creates 4 threads, each of which create and do reads and writes on
    a 2G file, with a buffer size of 256K, using O_DIRECT for all file opens
    to bypass the page cache.  Results:
    
                         ext2        ext4, default   ext4, no journal
      initial writes   13.0 MB/s        15.4 MB/s          15.7 MB/s
      rewrites         13.1 MB/s        15.6 MB/s          15.9 MB/s
      reads            15.2 MB/s        16.9 MB/s          17.2 MB/s
      re-reads         15.3 MB/s        16.9 MB/s          17.2 MB/s
      random readers    5.6 MB/s         5.6 MB/s           5.7 MB/s
      random writers    5.1 MB/s         5.3 MB/s           5.4 MB/s 
    
    So it seems that, so far, this was a useful exercise.
    Signed-off-by: default avatarFrank Mayhar <fmayhar@google.com>
    Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
    0390131b
extents.c 81.9 KB