Numbers: ext2/ext3/reiser Performance (ext3 is slow)

[Oktay Akbal]

Hello !

On my test to optimize mysql-Performance I noticed, that the sql-bench is
significantly slower when the tables are stored on a partition with
reiserfs than ext2. I assume this is normal due to the overhead of journal
in write-intensiv tasks. I reran the test with ext3 and was shocked how
slow the bench was then. Here are the numbers for my old K6/400 with
scsi-disks.

Time to complete sql-bench

ext2	176min
reiser  203min (+15%)
ext3    310min (+76%)   (first test with 2.4.14-ext3 319min)

I ran all tests multiple times. Since I used the same Kernels this
is not an vm-issue. I tested on 2.4.14, 2.4.14+ext3 and 2.5.15-pre2.
Since the sql-bench is not an pure fs-test the fs should only play a
minor role. +76% time on this test means to mean that either ext3 is
horible slow or has a severe bug.
For those who know sql-bench I say, that test-insert seems to be the worst
case. It shows
Total time: 5880 wallclock secs  for ext2 and 13277 for ext3.
swap was disabled during test.

Anyone has an idea, why this ext3 "fails" at this specific test while on
normal fs-benchmarks it is much better ?

Oktay