Bug 737585

Summary:	Hard disk performance far worse than on Fedora 15 2.6.40
Product:	[Fedora] Fedora	Reporter:	Klaus Lichtenwalder <klic>
Component:	kernel	Assignee:	Kernel Maintainer List <kernel-maint>
Status:	CLOSED ERRATA	QA Contact:	Fedora Extras Quality Assurance <extras-qa>
Severity:	low	Docs Contact:
Priority:	unspecified
Version:	16	CC:	bruno, gansalmon, itamar, jonathan, kernel-maint, madhu.chinakonda, mads
Target Milestone:	---
Target Release:	---
Hardware:	i686
OS:	Linux
Whiteboard:
Fixed In Version:	kernel-3.1.0-0.rc6.git0.0.fc16	Doc Type:	Bug Fix
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2011-09-15 15:15:46 UTC	Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

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
/dev/sda:
 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
/dev/sda:
 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):
kernel-3.1.0-0.rc5.git0.0.fc16.i686


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.

Klaus

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:

http://koji.fedoraproject.org/koji/taskinfo?taskID=3346292

Comment 4 Klaus Lichtenwalder 2011-09-13 19:02:22 UTC

Josh,
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.

Klaus

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.
https://admin.fedoraproject.org/updates/kernel-3.1.0-0.rc6.git0.0.fc16

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.