Messages in this thread | | | Date | Wed, 11 Jun 2008 19:58:53 +0000 (GMT) | From | Holger Kiehl <> | Subject | Re: Performance of ext4 |
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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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