Bug 737585 - Hard disk performance far worse than on Fedora 15 2.6.40
Summary: Hard disk performance far worse than on Fedora 15 2.6.40
Alias: None
Product: Fedora
Classification: Fedora
Component: kernel
Version: 16
Hardware: i686
OS: Linux
Target Milestone: ---
Assignee: Kernel Maintainer List
QA Contact: Fedora Extras Quality Assurance
Depends On:
TreeView+ depends on / blocked
Reported: 2011-09-12 16:03 UTC by Klaus Lichtenwalder
Modified: 2011-09-15 15:15 UTC (History)
7 users (show)

Fixed In Version: kernel-3.1.0-0.rc6.git0.0.fc16
Doc Type: Bug Fix
Doc Text:
Clone Of:
Last Closed: 2011-09-15 15:15:46 UTC

Attachments (Terms of Use)

Description Klaus Lichtenwalder 2011-09-12 16:03:37 UTC
Description of problem:
The hd performance of Fedora 16  3.1 rc[345] kernel is ca. 50% that of Fedora 15
Here's the hdparm output:

Fedora 15
 Timing cached reads:   1396 MB in  2.00 seconds = 698.33 MB/sec
 Timing buffered disk reads: 180 MB in  3.02 seconds =  59.66 MB/sec

Fedora 16
 Timing cached reads:   984 MB in  1.99 seconds = 494.18 MB/sec
 Timing buffered disk reads:  84 MB in  3.09 seconds =  27.20 MB/sec

This is consistent.

Also, the resume from hibernation takes twice to three times longer than with Fedora 15

Version-Release number of selected component (if applicable):

How reproducible:
hdparm, resume

Expected results:
About as fast as Fedora 15

Additional info:
I couldn't find anything with my google-fu, hope this is appropriate, I intentionally set the priority to low

Comment 1 Josh Boyer 2011-09-12 17:20:02 UTC
f16 kernels still have all of the kernel debugging options enabled whereas f15 does not.  Before we go worrying about performance issues, we should test on a kernel that has the debug stuff turned off.  We already know those options significantly slow down Xorg as well.

The next f16 kernel build should have them off.  I'll post a URL to it here for testing.

Comment 2 Klaus Lichtenwalder 2011-09-12 17:31:48 UTC
Great, thanks. I was expecting something along these lines, just not such a huge impact. Will wait and test.


Comment 3 Josh Boyer 2011-09-12 22:36:55 UTC
I've started a 3.1-rc6 build that has the debugging options disabled.  You can test this build when it completes:


Comment 4 Klaus Lichtenwalder 2011-09-13 19:02:22 UTC
thanks, this brings hard disk performance back at expected levels. More thorough tests will have to wait, as I have on of those "nice" netbooks from acer with a brcm4312 chip, which has to use the brcmsmac driver.


Comment 5 Josh Boyer 2011-09-13 19:33:26 UTC
Thanks for testing.  I'll put this in MODIFIED state for now.

Comment 6 Fedora Update System 2011-09-13 19:45:31 UTC
kernel-3.1.0-0.rc6.git0.0.fc16 has been submitted as an update for Fedora 16.

Comment 7 Bruno Wolff III 2011-09-14 20:23:03 UTC
Can we look at fixing this for f17 kernels as well? For now, I have just rebuilt an f17 kernel using the f16 config files. This is a pain to do, but things are so much slower with debugging enabled that I am losing so much time waiting for stuff to happen (kernel builds, yum updates) that run alternative kernels is the best answer for me now.

I don't know if this affects things, but in my case I am running dmcrypt on top of mdraid.

Comment 8 Dave Jones 2011-09-14 21:48:54 UTC
see comment 32 of bug 735268

Comment 9 Fedora Update System 2011-09-15 15:15:23 UTC
kernel-3.1.0-0.rc6.git0.0.fc16 has been pushed to the Fedora 16 stable repository.  If problems still persist, please make note of it in this bug report.

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