linux-sg2042/fs/jbd2
Theodore Ts'o 0e3d2a6313 ext4: Fix async commit mode to be safe by using a barrier
Previously the journal_async_commit mount option was equivalent to
using barrier=0 (and just as unsafe).  This patch fixes it so that we
eliminate the barrier before the commit block (by not using ordered
mode), and explicitly issuing an empty barrier bio after writing the
commit block.  Because of the journal checksum, it is safe to do this;
if the journal blocks are not all written before a power failure, the
checksum in the commit block will prevent the last transaction from
being replayed.

Using the fs_mark benchmark, using journal_async_commit shows a 50%
improvement:

FSUse%        Count         Size    Files/sec     App Overhead
     8         1000        10240         30.5            28242

vs.

FSUse%        Count         Size    Files/sec     App Overhead
     8         1000        10240         45.8            28620


Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
2009-09-11 09:30:12 -04:00
..
Kconfig fs/Kconfig: move ext2, ext3, ext4, JBD, JBD2 out 2008-10-20 11:43:59 -07:00
Makefile [PATCH] jbd2: rename jbd2 symbols to avoid duplication of jbd symbols 2006-10-11 11:14:15 -07:00
checkpoint.c jbd2: convert instrumentation from markers to tracepoints 2009-06-17 11:47:48 -04:00
commit.c ext4: Fix async commit mode to be safe by using a barrier 2009-09-11 09:30:12 -04:00
journal.c jbd2: Fail to load a journal if it is too short 2009-07-17 10:40:01 -04:00
recovery.c jbd2: fix error handling for checkpoint io 2008-10-10 20:29:13 -04:00
revoke.c jbd2: use SWRITE_SYNC_PLUG when writing synchronous revoke records 2009-04-14 07:50:56 -04:00
transaction.c jbd2: Annotate transaction start also for jbd2_journal_restart() 2009-08-17 21:23:17 -04:00