On Wed, 11 Jun 2008, Aneesh Kumar K.V wrote:
On Wed, Jun 11, 2008 at 08:02:32AM +0000, Holger Kiehl wrote:
2 years ago I used 2.6.16.8 but the hardware is still the same. So what has
happened with the performance of ext4? I noticed that 2 years ago I could
use extents+mballoc+delalloc, now there is only extents+mballoc in the
current kernels. Could delalloc make the big difference? I saw that
in Andrew Morton mm tree delalloc is included. Unfortunately when I tried using
2.6.26-rc2-mm1 a sync would never return and there where lot of other
odd things, so I could not do any tests with delalloc.
The sync and other related hangs should be fix with the latest patches
vailable at http://repo.or.cz/w/ext4-patch-queue.git. Using mballoc have
an impact on CPU utilization because we try to build an in-memory extent
map of free blocks available in the group. The cold cache run (the first
run) would take more time because of the time needed to build the extent
map. So repeating the same test and looking at the numbers would help us
understand the impact of in-memory extent building code.
Not sure if I understand this. I first formated the file system and run the
test three times.
So any idea what I am doing wrong or what I could do to improve those numbers?
Please CC me since I am not subscribed to the list.
You should be able to apply the patches in the patchqueue mentioned above to 2.6.26-rc5
Can you test with the same and get the numbers. ? Also delalloc enabled
by default with changes from patchqueue force writeback mode for
journal. So you may want to enable writeback for ext3.
Against a clean 2.6.26-rc5 the patchqueue does not apply. Lots of rejects.
The patchqueue also contains changes for defrag that are not in 2.6.26-rc5.
Or did you mean to apply those against the mm tree?
Thanks,
Holger
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